Texas Instruments TMS320x2833x, TMS320x2823x Reference Manual

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TMS320x2833x, 2823x Enhanced Pulse Width Modulator (ePWM) Module

Reference Guide

Literature Number: SPRUG04A

October 2008–Revised July 2009

SPRUG04A–October 2008–Revised July 2009

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Preface ....................................................................................................................................... 8

1 Introduction ...................................................................................................................... 11

1.1 Submodule Overview .................................................................................................. 11

1.2 Register Mapping ...................................................................................................... 15

2 ePWM Submodules ............................................................................................................ 17

2.1 Overview ................................................................................................................ 17

2.2 Time-Base (TB) Submodule .......................................................................................... 20

2.3 Counter-Compare (CC) Submodule ................................................................................. 31

2.4 Action-Qualifier (AQ) Submodule .................................................................................... 37

2.5 Dead-Band Generator (DB) Submodule ............................................................................ 51

2.6 PWM-Chopper (PC) Submodule ..................................................................................... 55

2.7 Trip-Zone (TZ) Submodule ........................................................................................... 59

2.8 Event-Trigger (ET) Submodule ....................................................................................... 63

3 Applications to Power Topologies ....................................................................................... 68

3.1 Overview of Multiple Modules ........................................................................................ 68

3.2 Key Configuration Capabilities ....................................................................................... 68

3.3 Controlling Multiple Buck Converters With Independent Frequencies .......................................... 69

3.4 Controlling Multiple Buck Converters With Same Frequencies .................................................. 73

3.5 Controlling Multiple Half H-Bridge (HHB) Converters ............................................................. 76

3.6 Controlling Dual 3-Phase Inverters for Motors (ACI and PMSM) ................................................ 78

3.7 Practical Applications Using Phase Control Between PWM Modules .......................................... 82

3.8 Controlling a 3-Phase Interleaved DC/DC Converter ............................................................. 83

3.9 Controlling Zero Voltage Switched Full Bridge (ZVSFB) Converter ............................................. 87

4 Registers .......................................................................................................................... 90

4.1 Time-Base Submodule Registers .................................................................................... 90

4.2 Counter-Compare Submodule Registers ........................................................................... 94

4.3 Action-Qualifier Submodule Registers .............................................................................. 97

4.4 Dead-Band Submodule Registers .................................................................................. 101

4.5 PWM-Chopper Submodule Control Register ..................................................................... 103

4.6 Trip-Zone Submodule Control and Status Registers ............................................................ 105

4.7 Event-Trigger Submodule Registers ............................................................................... 108

4.8 Proper Interrupt Initialization Procedure ........................................................................... 113

Appendix A Revision History ..................................................................................................... 114

SPRUG04A–October 2008–Revised July 2009 Table of Contents

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List of Figures

1 Multiple ePWM Modules.................................................................................................. 13

2 Submodules and Signal Connections for an ePWM Module ........................................................ 14

3 ePWM Submodules and Critical Internal Signal Interconnects...................................................... 15

4 Time-Base Submodule Block Diagram ................................................................................. 20

5 Time-Base Submodule Signals and Registers ........................................................................ 21

6 Time-Base Frequency and Period ...................................................................................... 23

7 Time-Base Counter Synchronization Scheme 1 ...................................................................... 25

8 Time-Base Counter Synchronization Scheme 2 ...................................................................... 26

9 Time-Base Counter Synchronization Scheme 3 ...................................................................... 27

10 Time-Base Up-Count Mode Waveforms................................................................................ 29

11 Time-Base Down-Count Mode Waveforms............................................................................ 30

12 Time-Base Up-Down-Count Waveforms, TBCTL[PHSDIR = 0] Count Down On Synchronization Event..... 30

13 Time-Base Up-Down Count Waveforms, TBCTL[PHSDIR = 1] Count Up On Synchronization Event......... 31

14 Counter-Compare Submodule........................................................................................... 31

15 Detailed View of the Counter-Compare Submodule.................................................................. 32

16 Counter-Compare Event Waveforms in Up-Count Mode ............................................................ 35

17 Counter-Compare Events in Down-Count Mode ...................................................................... 36

18 Counter-Compare Events In Up-Down-Count Mode, TBCTL[PHSDIR = 0] Count Down On

Synchronization Event ................................................................................................... 37

19 Counter-Compare Events In Up-Down-Count Mode, TBCTL[PHSDIR = 1] Count Up On Synchronization

Event ....................................................................................................................... 37

20 Action-Qualifier Submodule .............................................................................................. 38

21 Action-Qualifier Submodule Inputs and Outputs ...................................................................... 39

22 Possible Action-Qualifier Actions for EPWMxA and EPWMxB Outputs............................................ 40

23 Up-Down-Count Mode Symmetrical Waveform ....................................................................... 43

24 Up, Single Edge Asymmetric Waveform, With Independent Modulation on EPWMxA and

EPWMxB—Active High ................................................................................................... 44

25 Up, Single Edge Asymmetric Waveform With Independent Modulation on EPWMxA and

EPWMxB—Active Low.................................................................................................... 45

26 Up-Count, Pulse Placement Asymmetric Waveform With Independent Modulation on EPWMxA ............. 46

27 Up-Down-Count, Dual Edge Symmetric Waveform, With Independent Modulation on EPWMxA and

EPWMxB — Active Low.................................................................................................. 48

28 Up-Down-Count, Dual Edge Symmetric Waveform, With Independent Modulation on EPWMxA and

EPWMxB — Complementary ............................................................................................ 49

29 Up-Down-Count, Dual Edge Asymmetric Waveform, With Independent Modulation on EPWMxA—Active

Low.......................................................................................................................... 50

30 Dead_Band Submodule .................................................................................................. 51

31 Configuration Options for the Dead-Band Submodule ............................................................... 52

32 Dead-Band Waveforms for Typical Cases (0% < Duty < 100%).................................................... 53

33 PWM-Chopper Submodule............................................................................................... 55

34 PWM-Chopper Submodule Operational Details....................................................................... 56

35 Simple PWM-Chopper Submodule Waveforms Showing Chopping Action Only................................. 56

36 PWM-Chopper Submodule Waveforms Showing the First Pulse and Subsequent Sustaining Pulses........ 57

37 PWM-Chopper Submodule Waveforms Showing the Pulse Width (Duty Cycle) Control of Sustaining

Pulses....................................................................................................................... 58

38 Trip-Zone Submodule..................................................................................................... 59

39 Trip-Zone Submodule Mode Control Logic ............................................................................ 62

40 Trip-Zone Submodule Interrupt Logic................................................................................... 63

41 Event-Trigger Submodule ................................................................................................ 63

List of Figures SPRUG04A–October 2008–Revised July 2009

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42 Event-Trigger Submodule Inter-Connectivity of ADC Start of Conversion......................................... 64

43 Event-Trigger Submodule Showing Event Inputs and Prescaled Outputs......................................... 65

44 Event-Trigger Interrupt Generator....................................................................................... 66

45 Event-Trigger SOCA Pulse Generator.................................................................................. 67

46 Event-Trigger SOCB Pulse Generator.................................................................................. 67

47 Simplified ePWM Module................................................................................................. 68

48 EPWM1 Configured as a Typical Master, EPWM2 Configured as a Slave ....................................... 69

49 Control of Four Buck Stages. Here F

50 Buck Waveforms for (Note: Only three bucks shown here).......................................................... 71

51 Control of Four Buck Stages. (Note: F 52 Buck Waveforms for (Note: F 53 Control of Two Half-H Bridge Stages (F 54 Half-H Bridge Waveforms for (Note: Here F

55 Control of Dual 3-Phase Inverter Stages as Is Commonly Used in Motor Control ............................... 79

56 3-Phase Inverter Waveforms for (Only One Inverter Shown) ....................................................... 80

57 Configuring Two PWM Modules for Phase Control................................................................... 82

58 Timing Waveforms Associated With Phase Control Between 2 Modules.......................................... 83

59 Control of a 3-Phase Interleaved DC/DC Converter.................................................................. 84

60 3-Phase Interleaved DC/DC Converter Waveforms for .............................................................. 85

61 Controlling a Full-H Bridge Stage (F

62 ZVS Full-H Bridge Waveforms........................................................................................... 88

63 Time-Base Period Register (TBPRD)................................................................................... 90

64 Time-Base Phase Register (TBPHS)................................................................................... 90

65 Time-Base Counter Register (TBCTR)................................................................................. 90

66 Time-Base Control Register (TBCTL) .................................................................................. 91

67 Time-Base Status Register (TBSTS) ................................................................................... 93

68 Counter-Compare A Register (CMPA) ................................................................................. 94

69 Counter-Compare B Register (CMPB).................................................................................. 94

70 Counter-Compare Control Register (CMPCTL) ....................................................................... 96

71 Compare A High Resolution Register (CMPAHR) ................................................................... 97

72 Action-Qualifier Output A Control Register (AQCTLA) ............................................................... 97

73 Action-Qualifier Output B Control Register (AQCTLB) ............................................................... 98

74 Action-Qualifier Software Force Register (AQSFRC)................................................................. 99

75 Action-Qualifier Continuous Software Force Register (AQCSFRC)............................................... 100

76 Dead-Band Generator Control Register (DBCTL) ................................................................... 101

77 Dead-Band Generator Rising Edge Delay Register (DBRED)..................................................... 103

78 Dead-Band Generator Falling Edge Delay Register (DBFED)..................................................... 103

79 PWM-Chopper Control Register (PCCTL)............................................................................ 103

80 Trip-Zone Select Register (TZSEL).................................................................................... 105

81 Trip-Zone Control Register (TZCTL) .................................................................................. 106

82 Trip-Zone Enable Interrupt Register (TZEINT)....................................................................... 106

83 Trip-Zone Flag Register (TZFLG)...................................................................................... 107

84 Trip-Zone Clear Register (TZCLR) .................................................................................... 107

85 Trip-Zone Force Register (TZFRC).................................................................................... 108

86 Event-Trigger Selection Register (ETSEL) ........................................................................... 108

87 Event-Trigger Prescale Register (ETPS) ............................................................................. 109

88 Event-Trigger Flag Register (ETFLG)................................................................................. 111

89 Event-Trigger Clear Register (ETCLR)................................................................................ 112

90 Event-Trigger Force Register (ETFRC)............................................................................... 112

PWM2

= F

≠ F

PWM1

PWM2

= N x F

PWM2

)............................................................................. 74

PWM1)

= N x F

PWM2

= F

PWM2

PWM1)

≠ F

PWM3

).............................................................. 73

PWM1

)............................................................ 76

PWM1

= F

)............................................................ 77

PWM1

..................................................................... 87

.................................................... 70

PWM4

SPRUG04A–October 2008–Revised July 2009 List of Figures

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List of Tables

1 ePWM Module Control and Status Register Set Grouped by Submodule......................................... 16

2 Submodule Configuration Parameters.................................................................................. 17

3 Time-Base Submodule Registers ....................................................................................... 21

4 Key Time-Base Signals................................................................................................... 22

5 Counter-Compare Submodule Registers .............................................................................. 32

6 Counter-Compare Submodule Key Signals............................................................................ 33

7 Action-Qualifier Submodule Registers.................................................................................. 38

8 Action-Qualifier Submodule Possible Input Events ................................................................... 39

9 Action-Qualifier Event Priority for Up-Down-Count Mode............................................................ 41

10 Action-Qualifier Event Priority for Up-Count Mode.................................................................... 41

11 Action-Qualifier Event Priority for Down-Count Mode ................................................................ 41

12 Behavior if CMPA/CMPB is Greater than the Period................................................................. 41

13 Dead-Band Generator Submodule Registers.......................................................................... 51

14 Classical Dead-Band Operating Modes ............................................................................... 53

15 Dead-Band Delay Values in μS as a Function of DBFED and DBRED ........................................... 54

16 PWM-Chopper Submodule Registers .................................................................................. 55

17 Possible Pulse Width Values for SYSCLKOUT = 100 MHz ......................................................... 57

18 Trip-Zone Submodule Registers......................................................................................... 60

19 Possible Actions On a Trip Event ....................................................................................... 61

20 Event-Trigger Submodule Registers ................................................................................... 65

21 Time-Base Period Register (TBPRD) Field Descriptions ............................................................ 90

22 Time-Base Phase Register (TBPHS) Field Descriptions............................................................. 90

23 Time-Base Counter Register (TBCTR) Field Descriptions........................................................... 90

24 Time-Base Control Register (TBCTL) Field Descriptions ............................................................ 91

25 Time-Base Status Register (TBSTS) Field Descriptions ............................................................. 93

26 Counter-Compare A Register (CMPA) Field Descriptions ........................................................... 94

27 Counter-Compare B Register (CMPB) Field Descriptions ........................................................... 95

28 Counter-Compare Control Register (CMPCTL) Field Descriptions ................................................ 96

29 Compare A High Resolution Register (CMPAHR) Field Descriptions.............................................. 97

30 Action-Qualifier Output A Control Register (AQCTLA) Field Descriptions ........................................ 97

31 Action-Qualifier Output B Control Register (AQCTLB) Field Descriptions ........................................ 98

32 Action-Qualifier Software Force Register (AQSFRC) Field Descriptions .......................................... 99

33 Action-qualifier Continuous Software Force Register (AQCSFRC) Field Descriptions......................... 100

34 Dead-Band Generator Control Register (DBCTL) Field Descriptions............................................. 102

35 Dead-Band Generator Rising Edge Delay Register (DBRED) Field Descriptions............................... 103

36 Dead-Band Generator Falling Edge Delay Register (DBFED) Field Descriptions .............................. 103

37 PWM-Chopper Control Register (PCCTL) Bit Descriptions ....................................................... 104

38 Trip-Zone Submodule Select Register (TZSEL) Field Descriptions .............................................. 105

39 Trip-Zone Control Register (TZCTL) Field Descriptions ............................................................ 106

40 Trip-Zone Enable Interrupt Register (TZEINT) Field Descriptions ................................................ 106

41 Trip-Zone Flag Register (TZFLG) Field Descriptions ............................................................... 107

42 Trip-Zone Clear Register (TZCLR) Field Descriptions ............................................................. 108

43 Trip-Zone Force Register (TZFRC) Field Descriptions ............................................................. 108

44 Event-Trigger Selection Register (ETSEL) Field Descriptions .................................................... 109

45 Event-Trigger Prescale Register (ETPS) Field Descriptions ...................................................... 110

46 Event-Trigger Flag Register (ETFLG) Field Descriptions........................................................... 111

47 Event-Trigger Clear Register (ETCLR) Field Descriptions ......................................................... 112

List of Tables SPRUG04A–October 2008–Revised July 2009

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48 Event-Trigger Force Register (ETFRC) Field Descriptions ........................................................ 112

49 Changes for this Revision............................................................................................... 114

SPRUG04A–October 2008–Revised July 2009 List of Tables

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The Enhanced Pulse Width Modulator (ePWM) module described in this reference guide is a Type 0 ePWM. See the TMS320x28xx, 28xxx DSP Peripheral Reference Guide (SPRU566) for a list of all devices with a ePWM module of the same type, to determine the differences between the types, and for a list of device-specific differences within a type. This reference guide includes an overview of the module and information about each of its sub-modules:

• Time-Base Module

• Counter Compare Module

• Action Qualifier Module

• Dead-Band Generator Module

• PWM Chopper (PC) Module

• Trip Zone Module

• Event Trigger Module

Related Documentation From Texas Instruments

The following books describe the TMS320F2833x, 2823x module and related support tools that are available on the TI website:

Data Manual and Errata—

SPRS439 — TMS320F28335, TMS320F28334, TMS320F28332, TMS320F28235, TMS320F28234,

TMS320F28232 Digital Signal Controllers (DSCs) Data Manual contains the pinout, signal

descriptions, as well as electrical and timing specifications for the F2833x/2823x devices.

Preface

SPRUG04A–October 2008–Revised July 2009

Read This First

SPRZ272 — TMS320F28335, TMS320F28334, TMS320F28332, TMS320F28235, TMS320F28234,

TMS320F28232 DSC Silicon Errata describes the advisories and usage notes for different

versions of silicon.

CPU User's Guides—

SPRU430 — TMS320C28x CPU and Instruction Set Reference Guide describes the central processing

unit (CPU) and the assembly language instructions of the TMS320C28x fixed-point digital signal

processors (DSPs). It also describes emulation features available on these DSPs.

SPRUEO2 — TMS320C28x Floating Point Unit and Instruction Set Reference Guide describes the

floating-point unit and includes the instructions for the FPU.

Peripheral Guides—

SPRU566 — TMS320x28xx, 28xxx DSP Peripheral Reference Guide describes the peripheral

reference guides of the 28x digital signal processors (DSPs).

SPRUFB0 — TMS320x2833x, 2823x System Control and Interrupts Reference Guide describes the

various interrupts and system control features of the 2833x and 2823x digital signal controllers

(DSCs).

SPRU812 — TMS320x2833x, 2823x Analog-to-Digital Converter (ADC) Reference Guide describes

how to configure and use the on-chip ADC module, which is a 12-bit pipelined ADC.

SPRU949 — TMS320x2833x, 2823x DSC External Interface (XINTF) Reference Guide describes the

XINTF, which is a nonmultiplexed asynchronous bus, as it is used on the 2833x and 2823x devices.

Preface SPRUG04A–October 2008–Revised July 2009

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SPRU963 — TMS320x2833x, 2823x Boot ROM Reference Guide describes the purpose and features of

SPRUFB7 — TMS320x2833x, 2823x Multichannel Buffered Serial Port (McBSP) Reference Guide

SPRUFB8 — TMS320x2833x, 2823x Direct Memory Access (DMA) Module Reference Guide

SPRUG04 — TMS320x2833x, 2823x Enhanced Pulse Width Modulator (ePWM) Module Reference

SPRUG02 — TMS320x2833x, 2823x High-Resolution Pulse Width Modulator (HRPWM) Reference

SPRUFG4 — TMS320x2833x, 2823x Enhanced Capture (eCAP) Module Reference Guide describes

SPRUG05 — TMS320x2833x, 2823x Enhanced Quadrature Encoder Pulse (eQEP) Module

Related Documentation From Texas Instruments

the bootloader (factory-programmed boot-loading software) and provides examples of code. It also

describes other contents of the device on-chip boot ROM and identifies where all of the information

is located within that memory.

describes the McBSP available on the 2833x and 2823x devices. The McBSPs allow direct

interface between a DSP and other devices in a system.

describes the DMA on the 2833x and 2823x devices.

Guide describes the main areas of the enhanced pulse width modulator that include digital motor

control, switch mode power supply control, UPS (uninterruptible power supplies), and other forms of

power conversion.

Guide describes the operation of the high-resolution extension to the pulse width modulator

(HRPWM).

the enhanced capture module. It includes the module description and registers.

Reference Guide describes the eQEP module, which is used for interfacing with a linear or rotary

incremental encoder to get position, direction, and speed information from a rotating machine in

high-performance motion and position control systems. It includes the module description and

registers.

SPRUEU1 — TMS320x2833x, 2823x Enhanced Controller Area Network (eCAN) Reference Guide

describes the eCAN that uses established protocol to communicate serially with other controllers in

electrically noisy environments.

SPRUFZ5 — TMS320x2833x, 2823x Serial Communications Interface (SCI) Reference Guide

describes the SCI, which is a two-wire asynchronous serial port, commonly known as a UART. The

SCI modules support digital communications between the CPU and other asynchronous peripherals

that use the standard non-return-to-zero (NRZ) format.

SPRUEU3 — TMS320x2833x, 2823x DSC Serial Peripheral Interface (SPI) Reference Guide

describes the SPI - a high-speed synchronous serial input/output (I/O) port - that allows a serial bit

stream of programmed length (one to sixteen bits) to be shifted into and out of the device at a

programmed bit-transfer rate.

SPRUG03 — TMS320x2833x, 2823x Inter-Integrated Circuit (I2C) Module Reference Guide describes

the features and operation of the inter-integrated circuit (I2C) module.

Tools Guides—

SPRU513 — TMS320C28x Assembly Language Tools v5.0.0 User's Guide describes the assembly

language tools (assembler and other tools used to develop assembly language code), assembler

directives, macros, common object file format, and symbolic debugging directives for the

TMS320C28x device.

SPRU514 — TMS320C28x Optimizing C/C++ Compiler v5.0.0 User's Guide describes the

TMS320C28x™ C/C++ compiler. This compiler accepts ANSI standard C/C++ source code and

produces TMS320 DSP assembly language source code for the TMS320C28x device.

SPRU608 — TMS320C28x Instruction Set Simulator Technical Overview describes the simulator,

available within the Code Composer Studio for TMS320C2000 IDE, that simulates the instruction

set of the C28x™ core.

SPRU625 — TMS320C28x DSP/BIOS 5.32 Application Programming Interface (API) Reference

Guide describes development using DSP/BIOS.

SPRUG04A–October 2008–Revised July 2009 Read This First

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Related Documentation From Texas Instruments

Application Reports—

SPRAAM0 — Getting Started With TMS320C28x Digital Signal Controllers is organized by

development flow and functional areas to make your design effort as seamless as possible. Tips on

getting started with C28x™ DSP software and hardware development are provided to aid in your

initial design and debug efforts. Each section includes pointers to valuable information including

technical documentation, software, and tools for use in each phase of design.

SPRAAD5 — Power Line Communication for Lighting Applications Using Binary Phase Shift

Keying (BPSK) with a Single DSP Controller presents a complete implementation of a power line

modem following CEA-709 protocol using a single DSP.

SPRAA85 — Programming TMS320x28xx and 28xxx Peripherals in C/C++ explores a hardware

abstraction layer implementation to make C/C++ coding easier on 28x DSPs. This method is

compared to traditional #define macros and topics of code efficiency and special case registers are

also addressed.

SPRA958 — Running an Application from Internal Flash Memory on the TMS320F28xxx DSP covers

the requirements needed to properly configure application software for execution from on-chip flash

memory. Requirements for both DSP/BIOS™ and non-DSP/BIOS projects are presented. Example

code projects are included.

SPRAA91 — TMS320F280x Digital Signal Controller USB Connectivity Using the TUSB3410

USB-to-UART Bridge Chip presents hardware connections as well as software preparation and

operation of the development system using a simple communication echo program.

www.ti.com

SPRAAD8 — TMS320x280x and TMS320F2801x ADC Calibration describes a method for improving

the absolute accuracy of the 12-bit ADC found on the TMS320x280x and TMS320F2801x devices.

Inherent gain and offset errors affect the absolute accuracy of the ADC. The methods described in

this report can improve the absolute accuracy of the ADC to levels better than 0.5%. This

application report has an option to download an example program that executes from RAM on the

F2808 EzDSP.

SPRAAI1 — Using the ePWM Module for 0% – 100% Duty Cycle Control provides a guide for the use

of the ePWM module to provide 0% to 100% duty cycle control and is applicable to the

TMS320x280x family of processors.

SPRAA88 — Using PWM Output as a Digital-to-Analog Converter on a TMS320F280x Digital Signal

Controller presents a method for utilizing the on-chip pulse width modulated (PWM) signal

generators on the TMS320F280x family of digital signal controllers as a digital-to-analog converter

(DAC).

SPRAAH1 — Using the Enhanced Quadrature Encoder Pulse (eQEP) Module in TMS320x280x,

28xxx as a Dedicated Capture provides a guide for the use of the eQEP module as a dedicated

capture unit and is applicable to the TMS320x280x, 28xxx family of processors.

SPRA820 — Online Stack Overflow Detection on the TMS320C28x DSP presents the methodology for

online stack overflow detection on the TMS320C28x DSP. C-source code is provided that contains

functions for implementing the overflow detection on both DSP/BIOS and non-DSP/BIOS

applications.

SPRA806 — An Easy Way of Creating a C-callable Assembly Function for the TMS320C28x DSP

provides instructions and suggestions to configure the C compiler to assist with C-callable

assembly routines.

TMS320C28x, C28x are trademarks of Texas Instruments.

Read This First SPRUG04A–October 2008–Revised July 2009

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Reference Guide

SPRUG04A–October 2008–Revised July 2009

TMS320x2833x, 2823x Enhanced Pulse Width Modulator

(ePWM) Module

The enhanced pulse width modulator (ePWM) peripheral is a key element in controlling many of the power electronic systems found in both commercial and industrial equipments. These systems include digital motor control, switch mode power supply control, uninterruptible power supplies (UPS), and other forms of power conversion. The ePWM peripheral performs a digital to analog (DAC) function, where the duty cycle is equivalent to a DAC analog value; it is sometimes referred to as a Power DAC.

This reference guide is applicable for ePWM type 0 . See the TMS320x28xx, 28xxx DSP Peripheral Reference Guide (SPRU566) for a list of all devices with an ePWM module of the same type, to determine the differences between the types, and for a list of device-specific differences within a type.

1 Introduction

An effective PWM peripheral must be able to generate complex pulse width waveforms with minimal CPU overhead or intervention. It needs to be highly programmable and very flexible while being easy to understand and use. The ePWM unit described here addresses these requirements by allocating all needed timing and control resources on a per PWM channel basis. Cross coupling or sharing of resources has been avoided; instead, the ePWM is built up from smaller single channel modules with separate resources that can operate together as required to form a system. This modular approach results in an orthogonal architecture and provides a more transparent view of the peripheral structure, helping users to understand its operation quickly.

In this document the letter x within a signal or module name is used to indicate a generic ePWM instance on a device. For example output signals EPWMxA and EPWMxB refer to the output signals from the ePWMx instance. Thus, EPWM1A and EPWM1B belong to ePWM1 and likewise EPWM4A and EPWM4B belong to ePWM4.

1.1 Submodule Overview

The ePWM module represents one complete PWM channel composed of two PWM outputs: EPWMxA and EPWMxB. Multiple ePWM modules are instanced within a device as shown in Figure 1. Each ePWM instance is identical with one exception. Some instances include a hardware extension that allows more precise control of the PWM outputs. This extension is the high-resolution pulse width modulator (HRPWM) and is described in the TMS320x2833x, 2823x High-Resolution Pulse Width Modulator (HRPWM) Reference Guide (SPRUG02) . See the device-specific data manual to determine which ePWM instances include this feature. Each ePWM module is indicated by a numerical value starting with 1. For example ePWM1 is the first instance and ePWM3 is the 3rd instance in the system and ePWMx indicates any instance.

The ePWM modules are chained together via a clock synchronization scheme that allows them to operate as a single system when required. Additionally, this synchronization scheme can be extended to the capture peripheral modules (eCAP). The number of modules is device-dependent and based on target application needs. Modules can also operate stand-alone.

Each ePWM module supports the following features:

• Dedicated 16-bit time-base counter with period and frequency control

• Two PWM outputs (EPWMxA and EPWMxB) that can be used in the following configurations:

– Two independent PWM outputs with single-edge operation – Two independent PWM outputs with dual-edge symmetric operation

SPRUG04A–October 2008–Revised July 2009 TMS320x2833x, 2823x Enhanced Pulse Width Modulator (ePWM) Module

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Introduction

• Asynchronous override control of PWM signals through software.

• Programmable phase-control support for lag or lead operation relative to other ePWM modules.

• Hardware-locked (synchronized) phase relationship on a cycle-by-cycle basis.

• Dead-band generation with independent rising and falling edge delay control.

• Programmable trip zone allocation of both cycle-by-cycle trip and one-shot trip on fault conditions.

• A trip condition can force either high, low, or high-impedance state logic levels at PWM outputs.

• All events can trigger both CPU interrupts and ADC start of conversion (SOC)

• Programmable event prescaling minimizes CPU overhead on interrupts.

• PWM chopping by high-frequency carrier signal, useful for pulse transformer gate drives. Each ePWM module is connected to the input/output signals shown in Figure 1. The signals are described

in detail in subsequent sections.

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– One independent PWM output with dual-edge asymmetric operation

TMS320x2833x, 2823x Enhanced Pulse Width Modulator (ePWM) Module SPRUG04A–October 2008–Revised July 2009

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PIE

TZ1

toTZ6

Peripheral

Frame1

ePWM1module

ePWM2module

ePWMxmodule

SYNCO

SYNCI

SYNCO

SYNCI

SYNCO

ADC

GPIO

MUX

xSYNCI

xSYNCO

xSOC

EPWMxA

EPWMxB

EPWM2A

EPWM2B

EPWM1A

EPWM1B

EPWM1INT

EPWM1SOC

EPWM2INT

EPWM2SOC

EPWMxINT

EPWMxSOC

ToeCAP1

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Introduction

Figure 1. Multiple ePWM Modules

The order in which the ePWM modules are connected may differ from what is shown in Figure 1. See

Section 2.2.3.3 for the synchronization scheme for a particular device. Each ePWM module consists of

seven submodules and is connected within a system via the signals shown in Figure 2.

SPRUG04A–October 2008–Revised July 2009 TMS320x2833x, 2823x Enhanced Pulse Width Modulator (ePWM) Module

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EPWMxINT

EPWMxTZINT

EPWMxSOCA EPWMxSOCB

EPWMxSYNCI EPWMxSYNCO

Time-base (TB) module

Counter-compare (CC) module

Action-qualifier (AQ) module

Dead-band (DB) module

PWM-chopper (PC) module

Event-trigger (ET) module

Trip-zone (TZ) module

Peripheral bus

ePWM module

TZ1

to TZ6 EPWMxA EPWMxB

PIE

ADC

GPIO

MUX

Introduction

Figure 3 shows more internal details of a single ePWM module. The main signals used by the ePWM

module are:

• PWM output signals (EPWMxA and EPWMxB).

• Trip-zone signals (TZ1 to TZ6).

• Time-base synchronization input (EPWMxSYNCI) and output (EPWMxSYNCO) signals.

• ADC start-of-conversion signals (EPWMxSOCA and EPWMxSOCB).

• Peripheral Bus

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Figure 2. Submodules and Signal Connections for an ePWM Module

The PWM output signals are made available external to the device through the GPIO peripheral described in the system control and interrupts guide for your device.

These input signals alert the ePWM module of fault conditions external to the ePWM module. Each module on a device can be configured to either use or ignore any of the trip-zone signals. The TZ1 to TZ6 trip-zone signals can be configured as asynchronous inputs through the GPIO peripheral.

The synchronization signals daisy chain the ePWM modules together. Each module can be configured to either use or ignore its synchronization input. The clock synchronization input and output signal are brought out to pins only for ePWM1 (ePWM module #1). The synchronization output for ePWM1 (EPWM1SYNCO) is also connected to the SYNCI of the first enhanced capture module (eCAP1).

Each ePWM module has two ADC start of conversion signals (one for each sequencer). Any ePWM module can trigger a start of conversion for either sequencer. Which event triggers the start of conversion is configured in the Event-Trigger submodule of the ePWM.

The peripheral bus is 32-bits wide and allows both 16-bit and 32-bit writes to the ePWM register file.

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Action

qualifier

(AQ)

Time-base (TB)

Dead

band (DB)

Counter compare (CC)

Trip

zone

(TZ)

Event

trigger and

interrupt

(ET)

PWM

chopper

(PC)

TZ1 to TZ6

TBPRD shadow (16)

TBPRD active (16)

CTR = PRD CTR = ZERO CTR = CMPA CTR = CMPB

CTR_Dir

TBCTL[SWFSYNC] (software

forced sync)

TBPHS active (16)

Counter

UP/DWN

(16 bit)

TBCTR

active

(16)

Sync

in/out

select

MUX

CMPA active (16)

CMPA shadow (16)

CMPB active (16)

CMPB shadow (16)

EPWMxA

EPWMxB

EPWMxSOCB

EPWMxSOCA

EPWMxINT

EPWMxSYNCI

EPWMxSYNCO

TBCTL[SWFSYNC]

CTR_PRD

TBCTL[PHSEN]

CTR_Dir

CTR = ZERO

CTR = CMPA

CTR = CMPB

Phase control

EPWMxTZINT

CTR=ZERO

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Introduction

Figure 3. ePWM Submodules and Critical Internal Signal Interconnects

1.2 Register Mapping

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Figure 3 also shows the key internal submodule interconnect signals. Each submodule is described in

detail in its respective section.

The complete ePWM module control and status register set is grouped by submodule as shown in

Table 1. Each register set is duplicated for each instance of the ePWM module. The start address for each

ePWM register file instance on a device is specified in the appropriate data manual.

Introduction

TBCTL 0x0000 1 No Time-Base Control Register TBSTS 0x0001 1 No Time-Base Status Register TBPHSHR 0x0002 1 No Extension for HRPWM Phase Register TBPHS 0x0003 1 No Time-Base Phase Register TBCTR 0x0004 1 No Time-Base Counter Register TBPRD 0x0005 1 Yes Time-Base Period Register

CMPCTL 0x0007 1 No Counter-Compare Control Register CMPAHR 0x0008 1 Yes Extension for HRPWM Counter-Compare A Register CMPA 0x0009 1 Yes Counter-Compare A Register CMPB 0x000A 1 Yes Counter-Compare B Register

AQCTLA 0x000B 1 No Action-Qualifier Control Register for Output A (EPWMxA) AQCTLB 0x000C 1 No Action-Qualifier Control Register for Output B (EPWMxB) AQSFRC 0x000D 1 No Action-Qualifier Software Force Register AQCSFRC 0x000E 1 Yes Action-Qualifier Continuous S/W Force Register Set

DBCTL 0x000F 1 No Dead-Band Generator Control Register DBRED 0x0010 1 No Dead-Band Generator Rising Edge Delay Count Register DBFED 0x0011 1 No Dead-Band Generator Falling Edge Delay Count Register

TZSEL 0x0012 1 Yes Trip-Zone Select Register TZCTL 0x0014 1 Yes Trip-Zone Control Register TZEINT 0x0015 1 Yes Trip-Zone Enable Interrupt Register TZFLG 0x0016 1 Trip-Zone Flag Register TZCLR 0x0017 1 Yes Trip-Zone Clear Register TZFRC 0x0018 1 Yes Trip-Zone Force Register

ETSEL 0x0019 1 Event-Trigger Selection Register ETPS 0x001A 1 Event-Trigger Pre-Scale Register ETFLG 0x001B 1 Event-Trigger Flag Register ETCLR 0x001C 1 Event-Trigger Clear Register ETFRC 0x001D 1 Event-Trigger Force Register

PCCTL 0x001E 1 PWM-Chopper Control Register

HRCNFG 0x0020 1 Yes HRPWM Configuration Register

(1) (2)

(3)

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Table 1. ePWM Module Control and Status Register Set Grouped by Submodule

Offset Size

Name

Locations not shown are reserved. These registers are only available on ePWM instances that include the high-resolution PWM extension. Otherwise these

locations are reserved. These registers are described in the TMS320x2833x, 2823x High-Resolution Pulse Width Modulator (HRPWM) Reference Guide (SPRUG02) . See the device specific data manual to determine which instances include the HRPWM.

EALLOW protected registers as described in the specific device version of the System Control and Interrupts Reference Guide listed in Related Documentation From Texas Instruments.

(1)

(x16) Shadow EALLOW Description

Time-Base Submodule Registers

(2)

Counter-Compare Submodule Registers

(2)

Action-Qualifier Submodule Registers

Dead-Band Generator Submodule Registers

Trip-Zone Submodule Registers

(3)

Event-Trigger Submodule Registers

PWM-Chopper Submodule Registers

High-Resolution Pulse Width Modulator (HRPWM) Extension Registers

(2) (3)

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2 ePWM Submodules

Seven submodules are included in every ePWM peripheral. Each of these submodules performs specific tasks that can be configured by software.

2.1 Overview

Table 2 lists the seven key submodules together with a list of their main configuration parameters. For

example, if you need to adjust or control the duty cycle of a PWM waveform, then you should see the counter-compare submodule in Section 2.3 for relevant details.

Submodule Configuration Parameter or Option

Time-base (TB)

Counter-compare (CC)

Action-qualifier (AQ)

Dead-band (DB)

PWM-chopper (PC)

ePWM Submodules

Table 2. Submodule Configuration Parameters

• Scale the time-base clock (TBCLK) relative to the system clock (SYSCLKOUT).

• Configure the PWM time-base counter (TBCTR) frequency or period.

• Set the mode for the time-base counter: – count-up mode: used for asymmetric PWM – count-down mode: used for asymmetric PWM – count-up-and-down mode: used for symmetric PWM

• Configure the time-base phase relative to another ePWM module.

• Synchronize the time-base counter between modules through hardware or software.

• Configure the direction (up or down) of the time-base counter after a synchronization event.

• Configure how the time-base counter will behave when the device is halted by an emulator.

• Specify the source for the synchronization output of the ePWM module: – Synchronization input signal – Time-base counter equal to zero – Time-base counter equal to counter-compare B (CMPB) – No output synchronization signal generated.

• Specify the PWM duty cycle for output EPWMxA and/or output EPWMxB

• Specify the time at which switching events occur on the EPWMxA or EPWMxB output

• Specify the type of action taken when a time-base or counter-compare submodule event occurs: – No action taken – Output EPWMxA and/or EPWMxB switched high – Output EPWMxA and/or EPWMxB switched low – Output EPWMxA and/or EPWMxB toggled

• Force the PWM output state through software control

• Configure and control the PWM dead-band through software

• Control of traditional complementary dead-band relationship between upper and lower switches

• Specify the output rising-edge-delay value

• Specify the output falling-edge delay value

• Bypass the dead-band module entirely. In this case the PWM waveform is passed through

without modification.

• Create a chopping (carrier) frequency.

• Pulse width of the first pulse in the chopped pulse train.

• Duty cycle of the second and subsequent pulses.

• Bypass the PWM-chopper module entirely. In this case the PWM waveform is passed through

without modification.

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ePWM Submodules

Submodule Configuration Parameter or Option

Trip-zone (TZ)

Event-trigger (ET) • Enable the ePWM events that will trigger an interrupt.

Code examples are provided in the remainder of this document that show how to implement various ePWM module configurations. These examples use the constant definitions shown in Example 1. These definitions are also used in the C2833x/2823x C/C++ Header Files and Peripheral Examples (SPRC530) .

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Table 2. Submodule Configuration Parameters (continued)

• Configure the ePWM module to react to one, all, or none of the trip-zone pins .

• Specify the tripping action taken when a fault occurs: – Force EPWMxA and/or EPWMxB high – Force EPWMxA and/or EPWMxB low – Force EPWMxA and/or EPWMxB to a high-impedance state – Configure EPWMxA and/or EPWMxB to ignore any trip condition.

• Configure how often the ePWM will react to each trip-zone pins : – One-shot – Cycle-by-cycle

• Enable the trip-zone to initiate an interrupt.

• Bypass the trip-zone module entirely.

• Enable ePWM events that will trigger an ADC start-of-conversion event.

• Specify the rate at which events cause triggers (every occurrence or every second or third

occurrence)

• Poll, set, or clear event flags

Example 1. Constant Definitions Used in the Code Examples

// TBCTL (Time-Base Control) // = = = = = = = = = = = = = = = = = = = = = = = = = = // TBCTR MODE bits #define TB_COUNT_UP 0x0 #define TB_COUNT_DOWN 0x1 #define TB_COUNT_UPDOWN 0x2 #define TB_FREEZE 0x3 // PHSEN bit #define TB_DISABLE 0x0 #define TB_ENABLE 0x1 // PRDLD bit #define TB_SHADOW 0x0 #define TB_IMMEDIATE 0x1 // SYNCOSEL bits #define TB_SYNC_IN 0x0 #define TB_CTR_ZERO 0x1 #define TB_CTR_CMPB 0x2 #define TB_SYNC_DISABLE 0x3 // HSPCLKDIV and CLKDIV bits #define TB_DIV1 0x0 #define TB_DIV2 0x1 #define TB_DIV4 0x2 // PHSDIR bit #define TB_DOWN 0x0 #define TB_UP 0x1 // CMPCTL (Compare Control) // = = = = = = = = = = = = = = = = = = = = = = = = = = // LOADAMODE and LOADBMODE bits #define CC_CTR_ZERO 0x0 #define CC_CTR_PRD 0x1 #define CC_CTR_ZERO_PRD 0x2 # define CC_LD_DISABLE 0x3 // SHDWAMODE and SHDWBMODE bits #define CC_SHADOW 0x0 #define CC_IMMEDIATE 0x1 // AQCTLA and AQCTLB (Action-qualifier Control) // = = = = = = = = = = = = = = = = = = = = = = = = = = // ZRO, PRD, CAU, CAD, CBU, CBD bits

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Example 1. Constant Definitions Used in the Code Examples (continued)

#define AQ_NO_ACTION 0x0 #define AQ_CLEAR 0x1 #define AQ_SET 0x2 #define AQ_TOGGLE 0x3 // DBCTL (Dead-Band Control) // = = = = = = = = = = = = = = = = = = = = = = = = = = // MODE bits #define DB_DISABLE 0x0 #define DBA_ENABLE 0x1 #define DBB_ENABLE 0x2 #define DB_FULL_ENABLE 0x3 // POLSEL bits #define DB_ACTV_HI 0x0 #define DB_ACTV_LOC 0x1 #define DB_ACTV_HIC 0x2 #define DB_ACTV_LO 0x3 // PCCTL (chopper control) // = = = = = = = = = = = = = = = = = = = = = = = = = =

// CHPEN bit #define CHP_ENABLE 0x0 #define CHP_DISABLE 0x1 // CHPFREQ bits #define CHP_DIV1 0x0 #define CHP_DIV2 0x1 #define CHP_DIV3 0x2 #define CHP_DIV4 0x3 #define CHP_DIV5 0x4 #define CHP_DIV6 0x5 #define CHP_DIV7 0x6 #define CHP_DIV8 0x7 // CHPDUTY bits #define CHP1_8TH 0x0 #define CHP2_8TH 0x1 #define CHP3_8TH 0x2 #define CHP4_8TH 0x3 #define CHP5_8TH 0x4 #define CHP6_8TH 0x5 # define CHP7_8TH 0x6 // TZSEL (Trip-zone Select) // = = = = = = = = = = = = = = = = = = = = = = = = = = // CBCn and OSHTn bits #define TZ_ENABLE 0x0 #define TZ_DISABLE 0x1 // TZCTL (Trip-zone Control) // = = = = = = = = = = = = = = = = = = = = = = = = = = // TZA and TZB bits #define TZ_HIZ 0x0 #define TZ_FORCE_HI 0x1 #define TZ_FORCE_LO 0x2 #define TZ_DISABLE 0x3 // ETSEL (Event-trigger Select) // = = = = = = = = = = = = = = = = = = = = = = = = = = // INTSEL, SOCASEL, SOCBSEL bits #define ET_CTR_ZERO 0x1 #define ET_CTR_PRD 0x2 #define ET_CTRU_CMPA 0x4 #define ET_CTRD_CMPA 0x5 #define ET_CTRU_CMPB 0x6 #define ET_CTRD_CMPB 0x7 // ETPS (Event-trigger Prescale) // = = = = = = = = = = = = = = = = = = = = = = = = = = // INTPRD, SOCAPRD, SOCBPRD bits #define ET_DISABLE 0x0 #define ET_1ST 0x1 #define ET_2ND 0x2 #define ET_3RD 0x3

ePWM Submodules

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CTR = CMPB

CTR = CMPA

CTR_Dir

CTR = 0

CTR = PRD

Dead Band

(DB)

Counter

Compare

(CC)

Action

Qualifier

(AQ)

EPWMxA

EPWMxB

CTR = CMPB

CTR = 0

EPWMxINT

EPWMxSOCA

EPWMxSOCB

EPWMxA

EPWMxB

TZ1 to TZ6

CTR = CMPA

Time-Base

(TB)

CTR = PRD

CTR = 0

CTR_Dir

EPWMxSYNCI

EPWMxSYNCO

EPWMxTZINT

PWM-

chopper

(PC)

Event

Trigger

and

Interrupt

(ET)

Trip Zone

(TZ)

GPIO

MUX

ADC

PIE

ePWM Submodules

2.2 Time-Base (TB) Submodule

Each ePWM module has its own time-base submodule that determines all of the event timing for the ePWM module. Built-in synchronization logic allows the time-base of multiple ePWM modules to work together as a single system. Figure 4 illustrates the time-base module's place within the ePWM.

Figure 4. Time-Base Submodule Block Diagram

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2.2.1 Purpose of the Time-Base Submodule

You can configure the time-base submodule for the following:

• Specify the ePWM time-base counter (TBCTR) frequency or period to control how often events occur.

• Manage time-base synchronization with other ePWM modules.

• Maintain a phase relationship with other ePWM modules.

• Set the time-base counter to count-up, count-down, or count-up-and-down mode.

• Generate the following events: – CTR = PRD: Time-base counter equal to the specified period (TBCTR = TBPRD) .

– CTR = Zero: Time-base counter equal to zero (TBCTR = 0x0000).

• Configure the rate of the time-base clock; a prescaled version of the CPU system clock (SYSCLKOUT). This allows the time-base counter to increment/decrement at a slower rate.

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TBCTL[SYNCOSEL]

TBPRD

PeriodActive

TBPRD

PeriodShadow

TBCTL[SWFSYNC]

CTR=PRD

TBPHS

PhaseActiveReg

Counter

UP/DOWN

Sync

Out

Select

EPWMxSYNCO

Reset

Load

TBCTL[PHSEN]

CTR=Zero

CTR=CMPB

Disable

EPWMxSYNCI

TBCTL[PRDLD]

TBCTR[15:0]

Mode

TBCTL[CTRMODE]

CTR=Zero

CTR_max

TBCLK

Clock

Prescale

SYSCLKOUT

TBCLK

TBCTL[HSPCLKDIV]

TBCTL[CLKDIV]

CTR_dir

TBCTR

CounterActiveReg

clk

Max

Dir

Zero

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2.2.2 Controlling and Monitoring the Time-base Submodule

Table 3 shows the registers used to control and monitor the time-base submodule.

Table 3. Time-Base Submodule Registers

TBCTL 0x0000 No Time-Base Control Register TBSTS 0x0001 No Time-Base Status Register TBPHSHR 0x0002 No HRPWM Extension Phase Register TBPHS 0x0003 No Time-Base Phase Register TBCTR 0x0004 No Time-Base Counter Register TBPRD 0x0005 Yes Time-Base Period Register

(1)

This register is available only on ePWM instances that include the high-resolution extension (HRPWM). On ePWM modules that do not include the HRPWM, this location is reserved. This register is described in the device-specific High-Resolution Pulse Width Modulator (HRPWM) Reference Guide. See the device specific data manual to determine which ePWM instances include this feature.

The block diagram in Figure 5 shows the critical signals and registers of the time-base submodule.

Table 4 provides descriptions of the key signals associated with the time-base submodule.

Figure 5. Time-Base Submodule Signals and Registers

ePWM Submodules

(1)

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ePWM Submodules

Signal Description

EPWMxSYNCI Time-base synchronization input.

EPWMxSYNCO Time-base synchronization output.

CTR = PRD Time-base counter equal to the specified period.

CTR = Zero Time-base counter equal to zero

CTR = CMPB Time-base counter equal to active counter-compare B register (TBCTR = CMPB).

CTR_dir Time-base counter direction.

CTR_max Time-base counter equal max value. (TBCTR = 0xFFFF)

TBCLK Time-base clock.

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Table 4. Key Time-Base Signals

Input pulse used to synchronize the time-base counter with the counter of ePWM module earlier in the synchronization chain. An ePWM peripheral can be configured to use or ignore this signal. For the first ePWM module (EPWM1) this signal comes from a device pin. For subsequent ePWM modules this signal is passed from another ePWM peripheral. For example, EPWM2SYNCI is generated by the ePWM1 peripheral, EPWM3SYNCI is generated by ePWM2 and so forth. See Section 2.2.3.3 for information on the synchronization order of a particular device.

This output pulse is used to synchronize the counter of an ePWM module later in the synchronization chain. The ePWM module generates this signal from one of three event sources:

1. EPWMxSYNCI (Synchronization input pulse)

2. CTR = Zero: The time-base counter equal to zero (TBCTR = 0x0000).

3. CTR = CMPB: The time-base counter equal to the counter-compare B (TBCTR = CMPB) register.

This signal is generated whenever the counter value is equal to the active period register value. That is when TBCTR = TBPRD.

This signal is generated whenever the counter value is zero. That is when TBCTR equals 0x0000.

This event is generated by the counter-compare submodule and used by the synchronization out logic

Indicates the current direction of the ePWM's time-base counter. This signal is high when the counter is increasing and low when it is decreasing.

Generated event when the TBCTR value reaches its maximum value. This signal is only used only as a status bit

This is a prescaled version of the system clock (SYSCLKOUT) and is used by all submodules within the ePWM. This clock determines the rate at which time-base counter increments or decrements.

2.2.3 Calculating PWM Period and Frequency

The frequency of PWM events is controlled by the time-base period (TBPRD) register and the mode of the time-base counter. Figure 6 shows the period (T down-count, and up-down-count time-base counter modes when when the period is set to 4 (TBPRD = 4). The time increment for each step is defined by the time-base clock (TBCLK) which is a prescaled version of the system clock (SYSCLKOUT).

The time-base counter has three modes of operation selected by the time-base control register (TBCTL):

• Up-Down-Count Mode: In up-down-count mode, the time-base counter starts from zero and increments until the period

(TBPRD) value is reached. When the period value is reached, the time-base counter then decrements until it reaches zero. At this point the counter repeats the pattern and begins to increment.

• Up-Count Mode: In this mode, the time-base counter starts from zero and increments until it reaches the value in the

period register (TBPRD). When the period value is reached, the time-base counter resets to zero and begins to increment once again.

• Down-Count Mode: In down-count mode, the time-base counter starts from the period (TBPRD) value and decrements until

it reaches zero. When it reaches zero, the time-base counter is reset to the period value and it begins to decrement once again.

) and frequency (F

pwm

) relationships for the up-count,

pwm

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PRD

4 4

PRD

CTR_dir

Up Down Down

PWM =

(TBPRD + 1) x T

TBCLK

For Up Count and Down Count

For Up and Down Count

PWM =

1/ (T

PWM)

PWM =

2 x TBPRD x T

TBCLK

PWM =

1 / (T

PWM)

PWM

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ePWM Submodules

Figure 6. Time-Base Frequency and Period

2.2.3.1 Time-Base Period Shadow Register

The time-base period register (TBPRD) has a shadow register. Shadowing allows the register update to be synchronized with the hardware. The following definitions are used to describe all shadow registers in the ePWM module:

• Active Register The active register controls the hardware and is responsible for actions that the hardware causes or

invokes.

• Shadow Register direct effect on any control hardware. At a strategic point in time the shadow register's content is

transferred to the active register. This prevents corruption or spurious operation due to the register being asynchronously modified by software.

The memory address of the shadow period register is the same as the active register. Which register is written to or read from is determined by the TBCTL[PRDLD] bit. This bit enables and disables the TBPRD shadow register as follows:

• Time-Base Period Shadow Mode:

The shadow register buffers or provides a temporary holding location for the active register. It has no

The TBPRD shadow register is enabled when TBCTL[PRDLD] = 0. Reads from and writes to the TBPRD memory address go to the shadow register. The shadow register contents are transferred to the active register (TBPRD (Active) ← TBPRD (shadow)) when the time-base counter equals zero (TBCTR = 0x0000). By default the TBPRD shadow register is enabled.

• Time-Base Period Immediate Load Mode:

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If immediate load mode is selected (TBCTL[PRDLD] = 1), then a read from or a write to the TBPRD

ePWM Submodules

memory address goes directly to the active register.

2.2.3.2 Time-Base Clock Synchronization

The TBCLKSYNC bit in the peripheral clock enable registers allows all users to globally synchronize all enabled ePWM modules to the time-base clock (TBCLK). When set, all enabled ePWM module clocks are started with the first rising edge of TBCLK aligned. For perfectly synchronized TBCLKs, the prescalers for each ePWM module must be set identically.

The proper procedure for enabling ePWM clocks is as follows:

1. Enable ePWM module clocks in the PCLKCRx register

2. Set TBCLKSYNC= 0

3. Configure ePWM modules

4. Set TBCLKSYNC=1

2.2.3.3 Time-Base Counter Synchronization

A time-base synchronization scheme connects all of the ePWM modules on a device. Each ePWM module has a synchronization input (EPWMxSYNCI) and a synchronization output (EPWMxSYNCO). The input synchronization for the first instance (ePWM1) comes from an external pin. The possible synchronization connections for the remaining ePWM modules are shown in Figure 7, Figure 8, and

Figure 9.

Scheme 1 shown in Figure 7 applies to the 280x, 2801x, 2802x, and 2803x devices. Scheme 1 also applies to the 2804x devices when the ePWM pinout is configured for 280x compatible mode (GPAMCFG[EPWMMODE] = 0).

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EPWM2SYNCI

ePWM2

EPWM2SYNCO

EPWM1SYNCO

ePWM1

EPWM1SYNCI

GPIO

MUX

EPWM3SYNCO

ePWM3

EPWM3SYNCI

ePWMx

EPWMxSYNCI

SYNCI

eCAP1

EPWMxSYNCO

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ePWM Submodules

Figure 7. Time-Base Counter Synchronization Scheme 1

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EPWM1SYNCI

ePWM1

EPWM1SYNCO

GPIO

MUX

EPWM2SYNCI

ePWM2

EPWM2SYNCO

EPWM3SYNCI

ePWM3

EPWM3SYNCO

EPWM4SYNCI

ePWM4

EPWM4SYNCO

EPWM5SYNCI

ePWM5

EPWM5SYNCO

EPWM6SYNCI

ePWM6

EPWM36YNCO

EPWM7SYNCI

ePWM7

EPWM7SYNCO

EPWM9SYNCI

ePWM9

EPWM9SYNCO

EPWM10SYNCI

ePWM10

EPWM10SYNCO

EPWM11SYNCI

ePWM11

EPWM11SYNCO

EPWM13SYNCI

ePWM13

EPWM13SYnCO

EPWM14SYNCI

ePWM14

EPWM14SYNCO

EPWM15SYNCI

ePWM15

EPWM15SYNCO

EPWM8SYNCI

ePWM8

EPWM8SYNCO

EPWM12SYNCI

ePWM12

EPWM12SYNCO

EPWM16SYNCI

ePWM16

EPWM16SYNCO

SYNCI

eCAP1

ePWM Submodules

Scheme 2 shown in Figure 8 is used by the 2804x devices when the ePWM pinout is configured for A-channel only mode (GPAMCFG[EPWMMODE] = 3). If the 2804x ePWM pinout is configured for 280x compatible mode (GPAMCFG[EPWMMODE] = 0), then Scheme 1 is used.

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Figure 8. Time-Base Counter Synchronization Scheme 2

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EPWM1SYNCO

ePWM1

EPWM1SYNCI

GPIO

MUX

SYNCI

eCAP1

EPWM2SYNCI

ePWM2

EPWM2SYNCO

EPWM3SYNCO

ePWM3

EPWM3SYNCI

EPWM4SYNCI

ePWM4

EPWM4SYNCO

EPWM5SYNCO

ePWM5

EPWM5SYNCI

ePWM6

EPWM6SYNCI

eCAP4

EPWM7SYNCI

ePWM7

EPWM7SYNCO

EPWM8SYNCI

ePWM8

EPWM8SYNCO

EPWM9SYNCI

ePWM9

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Scheme 3, shown in Figure 9, is used by all other devices.

ePWM Submodules

Figure 9. Time-Base Counter Synchronization Scheme 3

NOTE: All modules shown in the synchronization schemes may not be available on all devices.

Please refer to the device specific data manual to determine which modules are available on a particular device.

Each ePWM module can be configured to use or ignore the synchronization input. If the TBCTL[PHSEN] bit is set, then the time-base counter (TBCTR) of the ePWM module will be automatically loaded with the phase register (TBPHS) contents when one of the following conditions occur:

• EPWMxSYNCI: Synchronization Input Pulse: The value of the phase register is loaded into the counter register when an input synchronization pulse

is detected (TBPHS → TBCTR). This operation occurs on the next valid time-base clock (TBCLK) edge.

The delay from internal master module to slave modules is given by: – if ( TBCLK = SYSCLKOUT): 2 x SYSCLKOUT

– if ( TBCLK != SYSCLKOUT):1 TBCLK

• Software Forced Synchronization Pulse: Writing a 1 to the TBCTL[SWFSYNC] control bit invokes a software forced synchronization. This pulse

is ORed with the synchronization input signal, and therefore has the same effect as a pulse on EPWMxSYNCI.

• This feature enables the ePWM module to be automatically synchronized to the time base of another

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ePWM module. Lead or lag phase control can be added to the waveforms generated by different ePWM modules to synchronize them. In up-down-count mode, the TBCTL[PSHDIR] bit configures the direction of the time-base counter immediately after a synchronization event. The new direction is independent of the direction prior to the synchronization event. The PHSDIR bit is ignored in count-up or count-down modes. See Figure 10 through Figure 13 for examples.

Clearing the TBCTL[PHSEN] bit configures the ePWM to ignore the synchronization input pulse. The synchronization pulse can still be allowed to flow-through to the EPWMxSYNCO and be used to synchronize other ePWM modules. In this way, you can set up a master time-base (for example, ePWM1) and downstream modules (ePWM2 - ePWMx) may elect to run in synchronization with the master. See the Application to Power Topologies Section 3 for more details on synchronization strategies.

2.2.4 Phase Locking the Time-Base Clocks of Multiple ePWM Modules

The TBCLKSYNC bit can be used to globally synchronize the time-base clocks of all enabled ePWM modules on a device. This bit is part of the device's clock enable registers and is described in the specific device version of the System Control and Interrupts Reference Guide listed in Related Documentation

From Texas Instruments. When TBCLKSYNC = 0, the time-base clock of all ePWM modules is stopped

(default). When TBCLKSYNC = 1, all ePWM time-base clocks are started with the rising edge of TBCLK aligned. For perfectly synchronized TBCLKs, the prescaler bits in the TBCTL register of each ePWM module must be set identically. The proper procedure for enabling the ePWM clocks is as follows:

1. Enable the individual ePWM module clocks. This is described in the specific device version of the System Control and Interrupts Reference Guide listed in Related Documentation From Texas

Instruments.

2. Set TBCLKSYNC = 0. This will stop the time-base clock within any enabled ePWM module.

3. Configure the prescaler values and desired ePWM modes.

4. Set TBCLKSYNC = 1.

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2.2.5 Time-base Counter Modes and Timing Waveforms

The time-base counter operates in one of four modes:

• Up-count mode which is asymmetrical.

• Down-count mode which is asymmetrical.

• Up-down-count which is symmetrical

• Frozen where the time-base counter is held constant at the current value

To illustrate the operation of the first three modes, the following timing diagrams show when events are generated and how the time-base responds to an EPWMxSYNCI signal.

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0000

TBCTR[15:0]

CTR_dir

CTR = zero

CNT_max

CTR = PRD

0xFFFF

TBPHS

(value)

TBPRD

(value)

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ePWM Submodules

Figure 10. Time-Base Up-Count Mode Waveforms

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0x000

0xFFFF

TBCTR[15:0]

TBPHS

(value)

TBPRD

(value)

CTR_dir

CTR = zero

CNT_max

CTR = PRD

0x0000

0xFFFF

TBCTR[15:0]

DOWN

TBPHS

(value)

TBPRD

(value)

CTR_dir

CTR=zero

CNT_max

CTR=PRD

ePWM Submodules

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Figure 11. Time-Base Down-Count Mode Waveforms

Figure 12. Time-Base Up-Down-Count Waveforms, TBCTL[PHSDIR = 0] Count Down On Synchronization

Event

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0x0000

0xFFFF

TBCTR[15:0]

DOWN

TBPHS(value)

TBPRD(value)

EPWMxSYNCI

CTR_dir

CTR=zero

CNT_max

CTR=PRD

CTR = CMPB

CTR = CMPA

CTR_Dir

CTR = 0

CTR = PRD

Dead Band

(DB)

Counter

Compare

(CC)

Action

Qualifier

(AQ)

EPWMxA

EPWMxB

CTR = CMPB

CTR = 0

EPWMxINT

EPWMxSOCA

EPWMxSOCB

EPWMxA

EPWMxB

TZ1 to TZ6

CTR = CMPA

Time-Base

(TB)

CTR = PRD

CTR = 0

CTR_Dir

EPWMxSYNCI

EPWMxSYNCO

EPWMxTZINT

PWM-

chopper

(PC)

Event

Trigger

and

Interrupt

(ET)

Trip Zone (TZ)

GPIO

MUX

ADC

PIE

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ePWM Submodules

Figure 13. Time-Base Up-Down Count Waveforms, TBCTL[PHSDIR = 1] Count Up On Synchronization

Event

2.3 Counter-Compare (CC) Submodule

Figure 14 illustrates the counter-compare submodule within the ePWM.

Figure 14. Counter-Compare Submodule

Figure 15 shows the basic structure of the counter-compare submodule.

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TBCTR[15:0]

Time Base

(TB)

Module

CMPA[15:0]

CMPA

CompareAActiveReg.

CTR=CMPA

CTR=CMPB

Action

Qualifier

Module

Digital

comparatorB

CMPB[15:0]

TBCTR[15:0]

CTR=PRD

CTR=0

CMPCTL[LOADAMODE]

Shadow

load

CTR=PRD

CTR=0

CMPCTL[LOADBMODE]

CMPCTL[SHDWBFULL]

CMPCTL[SHDWBMODE]

CMPCTL

[SHDWAFULL]

CMPCTL

[SHDWAMODE]

CMPA

CompareAShadowReg.

Digital

comparatorA

CMPB

CompareBActiveReg.

CMPB

CompareBShadowReg.

Shadow

load

(AQ)

ePWM Submodules

2.3.1 Purpose of the Counter-Compare Submodule

The counter-compare submodule takes as input the time-base counter value. This value is continuously compared to the counter-compare A (CMPA) and counter-compare B (CMPB) registers. When the time-base counter is equal to one of the compare registers, the counter-compare unit generates an appropriate event.

The counter-compare:

• Generates events based on programmable time stamps using the CMPA and CMPB registers – CTR = CMPA: Time-base counter equals counter-compare A register (TBCTR = CMPA).

– CTR = CMPB: Time-base counter equals counter-compare B register (TBCTR = CMPB)

• Controls the PWM duty cycle if the action-qualifier submodule is configured appropriately

• Shadows new compare values to prevent corruption or glitches during the active PWM cycle

2.3.2 Controlling and Monitoring the Counter-Compare Submodule

The counter-compare submodule operation is controlled and monitored by the registers shown in Table 5:

Table 5. Counter-Compare Submodule Registers

CMPCTL 0x0007 No Counter-Compare Control Register. CMPAHR 0x0008 Yes HRPWM Counter-Compare A Extension Register CMPA 0x0009 Yes Counter-Compare A Register CMPB 0x000A Yes Counter-Compare B Register

(1)

This register is available only on ePWM modules with the high-resolution extension (HRPWM). On ePWM modules that do not include the HRPWM this location is reserved. This register is described in the device-specific High-Resolution Pulse Width Modulator (HRPWM) Reference Guide. Refer to the device specific data manual to determine which ePWM instances include this feature.

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(1)

Figure 15. Detailed View of the Counter-Compare Submodule

The key signals associated with the counter-compare submodule are described in Table 6.

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Table 6. Counter-Compare Submodule Key Signals

Signal Description of Event Registers Compared

CTR = CMPA Time-base counter equal to the active counter-compare A value TBCTR = CMPA CTR = CMPB Time-base counter equal to the active counter-compare B value TBCTR = CMPB CTR = PRD Time-base counter equal to the active period. TBCTR = TBPRD

Used to load active counter-compare A and B registers from the shadow register

CTR = ZERO Time-base counter equal to zero. TBCTR = 0x0000

Used to load active counter-compare A and B registers from the shadow register

2.3.3 Operational Highlights for the Counter-Compare Submodule

The counter-compare submodule is responsible for generating two independent compare events based on two compare registers:

1. CTR = CMPA: Time-base counter equal to counter-compare A register (TBCTR = CMPA).

2. CTR = CMPB: Time-base counter equal to counter-compare B register (TBCTR = CMPB).

For up-count or down-count mode, each event occurs only once per cycle. For up-down-count mode each event occurs twice per cycle if the compare value is between 0x0000-TBPRD and once per cycle if the compare value is equal to 0x0000 or equal to TBPRD. These events are fed into the action-qualifier submodule where they are qualified by the counter direction and converted into actions if enabled. Refer to Section 2.4.1 for more details.

ePWM Submodules

The counter-compare registers CMPA and CMPB each have an associated shadow register. Shadowing provides a way to keep updates to the registers synchronized with the hardware. When shadowing is used, updates to the active registers only occur at strategic points. This prevents corruption or spurious operation due to the register being asynchronously modified by software. The memory address of the active register and the shadow register is identical. Which register is written to or read from is determined by the CMPCTL[SHDWAMODE] and CMPCTL[SHDWBMODE] bits. These bits enable and disable the CMPA shadow register and CMPB shadow register respectively. The behavior of the two load modes is described below:

Shadow Mode:

The shadow mode for the CMPA is enabled by clearing the CMPCTL[SHDWAMODE] bit and the shadow register for CMPB is enabled by clearing the CMPCTL[SHDWBMODE] bit. Shadow mode is enabled by default for both CMPA and CMPB.

If the shadow register is enabled then the content of the shadow register is transferred to the active register on one of the following events as specified by the CMPCTL[LOADAMODE] and CMPCTL[LOADBMODE] register bits:

• CTR = PRD: Time-base counter equal to the period (TBCTR = TBPRD).

• CTR = Zero: Time-base counter equal to zero (TBCTR = 0x0000)

• Both CTR = PRD and CTR = Zero

Only the active register contents are used by the counter-compare submodule to generate events to be sent to the action-qualifier.

Immediate Load Mode:

If immediate load mode is selected (i.e., TBCTL[SHADWAMODE] = 1 or TBCTL[SHADWBMODE] = 1), then a read from or a write to the register will go directly to the active register.

2.3.4 Count Mode Timing Waveforms

The counter-compare module can generate compare events in all three count modes:

• Up-count mode: used to generate an asymmetrical PWM waveform.

• Down-count mode: used to generate an asymmetrical PWM waveform.

• Up-down-count mode: used to generate a symmetrical PWM waveform.

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To best illustrate the operation of the first three modes, the timing diagrams in Figure 16 through Figure 19 show when events are generated and how the EPWMxSYNCI signal interacts.

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0x0000

0xFFFF

CTR=CMPA

TBCTR[15:0]

CMPA (value)

CMPB

(value)

TBPHS

(value)

TBPRD

(value)

CTR=CMPB

EPWMxSYNCI

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ePWM Submodules

Figure 16. Counter-Compare Event Waveforms in Up-Count Mode

NOTE: An EPWMxSYNCI external synchronization event can cause a discontinuity in the TBCTR count

sequence. This can lead to a compare event being skipped. This skipping is considered normal operation and must be taken into account.

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TBCTR[15:0]

0x0000

0xFFFF

CTR=CMPA

CMPA

(value)

CMPB

(value)

TBPHS

(value)

TBPRD

(value)

CTR=CMPB

EPWMxSYNCI

ePWM Submodules

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Figure 17. Counter-Compare Events in Down-Count Mode

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0x0000

0xFFFF

TBCTR[15:0]

CTR = CMPA

CMPA (value)

CMPB (value)

TBPHS (value)

TBPRD (value)

CTR = CMPB

EPWMxSYNCI

0x0000

0xFFFF

TBCTR[15:0]

CMPA

(value)

CMPB

(value)

TBPHS

(value)

TBPRD

(value)

CTR = CMPA

CTR = CMPB

EPWMxSYNCI

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ePWM Submodules

Figure 18. Counter-Compare Events In Up-Down-Count Mode, TBCTL[PHSDIR = 0] Count Down On

Synchronization Event

Figure 19. Counter-Compare Events In Up-Down-Count Mode, TBCTL[PHSDIR = 1] Count Up On

Synchronization Event

2.4 Action-Qualifier (AQ) Submodule

Figure 20 shows the action-qualifier (AQ) submodule (see shaded block) in the ePWM system.

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CTR = CMPB

CTR = CMPA

CTR_Dir

CTR = 0

CTR = PRD

Dead Band

(DB)

Counter

Compare

(CC)

Action

Qualifier

(AQ)

EPWMxA

EPWMxB

CTR = CMPB

CTR = 0

EPWMxINT

EPWMxSOCA

EPWMxSOCB

EPWMxA

EPWMxB

TZ1 to TZ6

CTR = CMPA

Time-Base

(TB)

CTR = PRD

CTR = 0

CTR_Dir

EPWMxSYNCI

EPWMxSYNCO

EPWMxTZINT

PWM-

chopper

(PC)

Event

Trigger

and

Interrupt

(ET)

Trip Zone (TZ)

GPIO

MUX

ADC

PIE

ePWM Submodules

The action-qualifier submodule has the most important role in waveform construction and PWM generation. It decides which events are converted into various action types, thereby producing the required switched waveforms at the EPWMxA and EPWMxB outputs.

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Figure 20. Action-Qualifier Submodule

2.4.1 Purpose of the Action-Qualifier Submodule

The action-qualifier submodule is responsible for the following:

• Qualifying and generating actions (set, clear, toggle) based on the following events: – CTR = PRD: Time-base counter equal to the period (TBCTR = TBPRD).

– CTR = Zero: Time-base counter equal to zero (TBCTR = 0x0000) – CTR = CMPA: Time-base counter equal to the counter-compare A register (TBCTR = CMPA) – CTR = CMPB: Time-base counter equal to the counter-compare B register (TBCTR = CMPB)

• Managing priority when these events occur concurrently

• Providing independent control of events when the time-base counter is increasing and when it is decreasing. .

2.4.2 Action-Qualifier Submodule Control and Status Register Definitions

The action-qualifier submodule operation is controlled and monitored via the registers in Table 7.

Table 7. Action-Qualifier Submodule Registers

Name

AQCTLA 0x000B No Action-Qualifier Control Register For Output A (EPWMxA) AQCTLB 0x000C No Action-Qualifier Control Register For Output B (EPWMxB) AQSFRC 0x000D No Action-Qualifier Software Force Register AQCSFRC 0x000E Yes Action-Qualifier Continuous Software Force

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Action-qualifier(AQ)Module

AQCTLA[15:0]

Action-qualifiercontrolA

EPWMA

EPWMB

TBCLK

CTR=PRD

CTR=Zero

CTR=CMPA

CTR=CMPB

CTR_dir

AQCTLB[15:0]

Action-qualifiercontrolB

AQSFRC[15:0]

Action-qualifierS/Wforce

AQCSFRC[3:0](shadow)

continuousS/Wforce

AQCSFRC[3:0](active)

continuousS/Wforce

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The action-qualifier submodule is based on event-driven logic. It can be thought of as a programmable cross switch with events at the input and actions at the output, all of which are software controlled via the set of registers shown in Table 7.

ePWM Submodules

Figure 21. Action-Qualifier Submodule Inputs and Outputs

For convenience, the possible input events are summarized again in Table 8.

Table 8. Action-Qualifier Submodule Possible Input Events

Signal Description Registers Compared

CTR = PRD Time-base counter equal to the period value TBCTR = TBPRD CTR = Zero Time-base counter equal to zero TBCTR = 0x0000 CTR = CMPA Time-base counter equal to the counter-compare A TBCTR = CMPA CTR = CMPB Time-base counter equal to the counter-compare B TBCTR = CMPB Software forced event Asynchronous event initiated by software

The software forced action is a useful asynchronous event. This control is handled by registers AQSFRC and AQCSFRC.

The action-qualifier submodule controls how the two outputs EPWMxA and EPWMxB behave when a particular event occurs. The event inputs to the action-qualifier submodule are further qualified by the counter direction (up or down). This allows for independent action on outputs on both the count-up and count-down phases.

The possible actions imposed on outputs EPWMxA and EPWMxB are:

• Set High: Set output EPWMxA or EPWMxB to a high level.

• Clear Low: Set output EPWMxA or EPWMxB to a low level.

• Toggle: If EPWMxA or EPWMxB is currently pulled high, then pull the output low. If EPWMxA or EPWMxB is

currently pulled low, then pull the output high.

• Do Nothing: Keep outputs EPWMxA and EPWMxB at same level as currently set. Although the "Do Nothing" option

prevents an event from causing an action on the EPWMxA and EPWMxB outputs, this event can still trigger interrupts and ADC start of conversion. See the Event-trigger Submodule description in

Section 2.8 for details.

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Z T

P T

CB P

Do Nothing

Clear Low

Set High

Toggle

Zero

Comp

Period

TB Counter equals:

Actions

S/W

force

ePWM Submodules

Actions are specified independently for either output (EPWMxA or EPWMxB). Any or all events can be configured to generate actions on a given output. For example, both CTR = CMPA and CTR = CMPB can operate on output EPWMxA. All qualifier actions are configured via the control registers found at the end of this section.

For clarity, the drawings in this document use a set of symbolic actions. These symbols are summarized in

Figure 22. Each symbol represents an action as a marker in time. Some actions are fixed in time (zero

and period) while the CMPA and CMPB actions are moveable and their time positions are programmed via the counter-compare A and B registers, respectively. To turn off or disable an action, use the "Do Nothing option"; it is the default at reset.

Figure 22. Possible Action-Qualifier Actions for EPWMxA and EPWMxB Outputs

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2.4.3 Action-Qualifier Event Priority

It is possible for the ePWM action qualifier to receive more than one event at the same time. In this case events are assigned a priority by the hardware. The general rule is events occurring later in time have a higher priority and software forced events always have the highest priority. The event priority levels for up-down-count mode are shown in Table 9. A priority level of 1 is the highest priority and level 7 is the lowest. The priority changes slightly depending on the direction of TBCTR.

Table 9. Action-Qualifier Event Priority for Up-Down-Count Mode

Priority Level Event If TBCTR is Incrementing Event If TBCTR is Decrementing

TBCTR = Zero up to TBCTR = TBPRD TBCTR = TBPRD down to TBCTR = 1

1 (Highest) Software forced event Software forced event

2 Counter equals CMPB on up-count (CBU) Counter equals CMPB on down-count (CBD) 3 Counter equals CMPA on up-count (CAU) Counter equals CMPA on down-count (CAD) 4 Counter equals zero Counter equals period (TBPRD) 5 Counter equals CMPB on down-count (CBD) Counter equals CMPB on up-count (CBU)

6 (Lowest) Counter equals CMPA on down-count (CAD) Counter equals CMPA on up-count (CBU)

Table 10 shows the action-qualifier priority for up-count mode. In this case, the counter direction is always

defined as up and thus down-count events will never be taken.

Table 10. Action-Qualifier Event Priority for Up-Count Mode

Priority Level Event

1 (Highest) Software forced event

2 Counter equal to period (TBPRD) 3 Counter equal to CMPB on up-count (CBU) 4 Counter equal to CMPA on up-count (CAU)

5 (Lowest) Counter equal to Zero

ePWM Submodules

Table 11 shows the action-qualifier priority for down-count mode. In this case, the counter direction is

always defined as down and thus up-count events will never be taken.

Table 11. Action-Qualifier Event Priority for Down-Count Mode

Priority Level Event

1 (Highest) Software forced event

2 Counter equal to Zero 3 Counter equal to CMPB on down-count (CBD) 4 Counter equal to CMPA on down-count (CAD)

5 (Lowest) Counter equal to period (TBPRD)

It is possible to set the compare value greater than the period. In this case the action will take place as shown in Table 12.

Table 12. Behavior if CMPA/CMPB is Greater than the Period

Counter Mode Compare on Up-Count Event Compare on Down-Count Event

Up-Count Mode If CMPA/CMPB ≤ TBPRD period, then the event Never occurs.

Down-Count Mode Never occurs. If CMPA/CMPB < TBPRD, the event will occur on a

CAD/CBD CAD/CBD

occurs on a compare match (TBCTR=CMPA or CMPB).

If CMPA/CMPB > TBPRD, then the event will not occur.

compare match (TBCTR=CMPA or CMPB). If CMPA/CMPB ≥ TBPRD, the event will occur on a

period match (TBCTR=TBPRD).

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ePWM Submodules

Table 12. Behavior if CMPA/CMPB is Greater than the Period (continued)

Counter Mode Compare on Up-Count Event Compare on Down-Count Event

CAD/CBD CAD/CBD

Up-Down-Count If CMPA/CMPB < TBPRD and the counter is If CMPA/CMPB < TBPRD and the counter is

Mode incrementing, the event occurs on a compare match decrementing, the event occurs on a compare match

(TBCTR=CMPA or CMPB). (TBCTR=CMPA or CMPB). If CMPA/CMPB is ≥ TBPRD, the event will occur on a If CMPA/CMPB ≥ TBPRD, the event occurs on a

period match (TBCTR = TBPRD). period match (TBCTR=TBPRD).

2.4.4 Waveforms for Common Configurations

NOTE: The waveforms in this document show the ePWMs behavior for a static compare register

value. In a running system, the active compare registers (CMPA and CMPB) are typically updated from their respective shadow registers once every period. The user specifies when the update will take place; either when the time-base counter reaches zero or when the time-base counter reaches period. There are some cases when the action based on the new value can be delayed by one period or the action based on the old value can take effect for an extra period. Some PWM configurations avoid this situation. These include, but are not limited to, the following:

Use up-down-count mode to generate a symmetric PWM:

• If you load CMPA/CMPB on zero, then use CMPA/CMPB values greater than or equal to 1.

• If you load CMPA/CMPB on period, then use CMPA/CMPB values less than or equal to TBPRD-1.

This means there will always be a pulse of at least one TBCLK cycle in a PWM period which, when very short, tend to be ignored by the system.

Use up-down-count mode to generate an asymmetric PWM:

• To achieve 50%-0% asymmetric PWM use the following configuration: Load CMPA/CMPB on period and use the period action to clear the PWM and a compare-up action to set the PWM. Modulate the compare value from 0 to TBPRD to achieve 50%-0% PWM duty.

When using up-count mode to generate an asymmetric PWM:

• To achieve 0-100% asymmetric PWM use the following configuration: Load CMPA/CMPB on TBPRD. Use the Zero action to set the PWM and a compare-up action to clear the PWM. Modulate the compare value from 0 to TBPRD+1 to achieve 0-100% PWM duty.

See the Using Enhanced Pulse Width Modulator (ePWM) Module for 0-100% Duty Cycle Control Application Report (literature number SPRAAI1)

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Figure 23 shows how a symmetric PWM waveform can be generated using the up-down-count mode of

the TBCTR. In this mode 0%-100% DC modulation is achieved by using equal compare matches on the up count and down count portions of the waveform. In the example shown, CMPA is used to make the comparison. When the counter is incrementing the CMPA match will pull the PWM output high. Likewise, when the counter is decrementing the compare match will pull the PWM signal low. When CMPA = 0, the PWM signal is low for the entire period giving the 0% duty waveform. When CMPA = TBPRD, the PWM signal is high achieving 100% duty.

When using this configuration in practice, if you load CMPA/CMPB on zero, then use CMPA/CMPB values greater than or equal to 1. If you load CMPA/CMPB on period, then use CMPA/CMPB values less than or equal to TBPRD-1. This means there will always be a pulse of at least one TBCLK cycle in a PWM period which, when very short, tend to be ignored by the system.

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DOWN

TBCTR

TBCTRDirection

EPWMxA/EPWMxB

Case2:

CMPA =3,25%Duty

Case3:

CMPA =2,50%Duty

Case3:

CMPA =1,75%Duty

Case4:

CMPA =0,100%Duty

Case1:

CMPA =4,0%Duty

EPWMxA/EPWMxB

Mode:Up-DownCount TBPRD=4 CAU=SET,CAD=CLEAR 0%-100%Duty

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ePWM Submodules

Figure 23. Up-Down-Count Mode Symmetrical Waveform

The PWM waveforms in Figure 24 through Figure 29 show some common action-qualifier configurations. The C-code samples in Example 2 through Example 7 shows how to configure an ePWM module for each case. Some conventions used in the figures and examples are as follows:

• TBPRD, CMPA, and CMPB refer to the value written in their respective registers. The active register, not the shadow register, is used by the hardware.

• CMPx, refers to either CMPA or CMPB.

• EPWMxA and EPWMxB refer to the output signals from ePWMx

• Up-Down means Count-up-and-down mode, Up means up-count mode and Dwn means down-count mode

• Sym = Symmetric, Asym = Asymmetric

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TBCTR

EPWMxB

TBPRD

value

CAZ P CB Z P CB CA Z P

Z P CA Z P CA Z PCBCB

ePWM Submodules

Figure 24. Up, Single Edge Asymmetric Waveform, With Independent Modulation on EPWMxA and

EPWMxB—Active High

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A PWM period = (TBPRD + 1 ) × T B Duty modulation for EPWMxA is set by CMPA, and is active high (that is, high time duty proportional to CMPA). C Duty modulation for EPWMxB is set by CMPB and is active high (that is, high time duty proportional to CMPB). D The "Do Nothing" actions ( X ) are shown for completeness, but will not be shown on subsequent diagrams. E Actions at zero and period, although appearing to occur concurrently, are actually separated by one TBCLK period.

TBCTR wraps from period to 0000.

TBCLK

Example 2 contains a code sample showing initialization and run time for the waveforms in Figure 24.

Example 2. Code Sample for Figure 24

// Initialization Time // = = = = = = = = = = = = = = = = = = = = = = = = EPwm1Regs.TBPRD = 600; // Period = 601 TBCLK counts EPwm1Regs.CMPA.half.CMPA = 350; // Compare A = 350 TBCLK counts EPwm1Regs.CMPB = 200; // Compare B = 200 TBCLK counts EPwm1Regs.TBPHS = 0; // Set Phase register to zero EPwm1Regs.TBCTR = 0; // clear TB counter EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP; EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE; // Phase loading disabled EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW; EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE; EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1; // TBCLK = SYSCLK EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV1; EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR = Zero EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR = Zero EPwm1Regs.AQCTLA.bit.ZRO = AQ_SET; EPwm1Regs.AQCTLA.bit.CAU = AQ_CLEAR; EPwm1Regs.AQCTLB.bit.ZRO = AQ_SET; EPwm1Regs.AQCTLB.bit.CBU = AQ_CLEAR; // // Run Time // = = = = = = = = = = = = = = = = = = = = = = = = EPwm1Regs.CMPA.half.CMPA = Duty1A; // adjust duty for output EPWM1A EPwm1Regs.CMPB = Duty1B; // adjust duty for output EPWM1B

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TBCTR

EPWMxB

TBPRD

value

CAP

P P

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ePWM Submodules

Figure 25. Up, Single Edge Asymmetric Waveform With Independent Modulation on EPWMxA and

EPWMxB—Active Low

A PWM period = (TBPRD + 1 ) × T B Duty modulation for EPWMxA is set by CMPA, and is active low (that is, the low time duty is proportional to CMPA). C Duty modulation for EPWMxB is set by CMPB and is active low (that is, the low time duty is proportional to CMPB). D Actions at zero and period, although appearing to occur concurrently, are actually separated by one TBCLK period.

TBCTR wraps from period to 0000.

TBCLK

Example 3 contains a code sample showing initialization and run time for the waveforms in Figure 25.

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TBCTR

EPWMxB

TBPRD

value

Z T

ePWM Submodules

Example 3. Code Sample for Figure 25

// Initialization Time // = = = = = = = = = = = = = = = = = = = = = = = = EPwm1Regs.TBPRD = 600; // Period = 601 TBCLK counts EPwm1Regs.CMPA.half.CMPA = 350; // Compare A = 350 TBCLK counts EPwm1Regs.CMPB = 200; // Compare B = 200 TBCLK counts EPwm1Regs.TBPHS = 0; // Set Phase register to zero EPwm1Regs.TBCTR = 0; // clear TB counter EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP; EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE; // Phase loading disabled EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW; EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE; EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1; // TBCLK = SYSCLKOUT EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV1; EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on TBCTR = Zero EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on TBCTR = Zero EPwm1Regs.AQCTLA.bit.PRD = AQ_CLEAR; EPwm1Regs.AQCTLA.bit.CAU = AQ_SET; EPwm1Regs.AQCTLB.bit.PRD = AQ_CLEAR; EPwm1Regs.AQCTLB.bit.CBU = AQ_SET; // // Run Time // = = = = = = = = = = = = = = = = = = = = = = = = EPwm1Regs.CMPA.half.CMPA = Duty1A; // adjust duty for output EPWM1A EPwm1Regs.CMPB = Duty1B; // adjust duty for output EPWM1B

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Figure 26. Up-Count, Pulse Placement Asymmetric Waveform With Independent Modulation on EPWMxA

A PWM frequency = 1/( (TBPRD + 1 ) × T B Pulse can be placed anywhere within the PWM cycle (0000 - TBPRD) C High time duty proportional to (CMPB - CMPA) D EPWMxB can be used to generate a 50% duty square wave with frequency = × ( (TBPRD + 1 ) × TBCLK )

TBCLK

)

Example 4 contains a code sample showing initialization and run time for the waveforms Figure 26. Use

the code in to define the headers.

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Example 4. Code Sample for Figure 26

// Initialization Time // = = = = = = = = = = = = = = = = = = = = = = = = EPwm1Regs.TBPRD = 600; // Period = 601 TBCLK counts EPwm1Regs.CMPA.half.CMPA = 200; // Compare A = 200 TBCLK counts EPwm1Regs.CMPB = 400; // Compare B = 400 TBCLK counts EPwm1Regs.TBPHS = 0; // Set Phase register to zero EPwm1Regs.TBCTR = 0; // clear TB counter EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP; EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE; // Phase loading disabled EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW; EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE; EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1; // TBCLK = SYSCLKOUT EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV1; EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on TBCTR = Zero EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on TBCTR = Zero EPwm1Regs.AQCTLA.bit.CAU = AQ_SET; EPwm1Regs.AQCTLA.bit.CBU = AQ_CLEAR; EPwm1Regs.AQCTLB.bit.ZRO = AQ_TOGGLE; // // Run Time // = = = = = = = = = = = = = = = = = = = = = = = = EPwm1Regs.CMPA.half.CMPA = EdgePosA; // adjust duty for output EPWM1A only EPwm1Regs.CMPB = EdgePosB;

ePWM Submodules

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TBCTR

EPWMxA

EPWMxB

TBPRD

value

CBCB

ePWM Submodules

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Figure 27. Up-Down-Count, Dual Edge Symmetric Waveform, With Independent Modulation on EPWMxA

and EPWMxB — Active Low

A PWM period = 2 x TBPRD × T B Duty modulation for EPWMxA is set by CMPA, and is active low (that is, the low time duty is proportional to CMPA). C Duty modulation for EPWMxB is set by CMPB and is active low (that is, the low time duty is proportional to CMPB). D Outputs EPWMxA and EPWMxB can drive independent power switches

TBCLK

Example 5 contains a code sample showing initialization and run time for the waveforms in Figure 27. Use

the code in to define the headers.

Example 5. Code Sample for Figure 27

// Initialization Time // = = = = = = = = = = = = = = = = = = = = = = = = EPwm1Regs.TBPRD = 600; // Period = 2´600 TBCLK counts EPwm1Regs.CMPA.half.CMPA = 400; // Compare A = 400 TBCLK counts EPwm1Regs.CMPB = 500; // Compare B = 500 TBCLK counts EPwm1Regs.TBPHS = 0; // Set Phase register to zero EPwm1Regs.TBCTR = 0; // clear TB counter EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetric xEPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE; // Phase loading disabled xEPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW; EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE; EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1; // TBCLK = SYSCLKOUT EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV1; EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR = Zero EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR = Zero EPwm1Regs.AQCTLA.bit.CAU = AQ_SET; EPwm1Regs.AQCTLA.bit.CAD = AQ_CLEAR; EPwm1Regs.AQCTLB.bit.CBU = AQ_SET; EPwm1Regs.AQCTLB.bit.CBD = AQ_CLEAR; // // Run Time // = = = = = = = = = = = = = = = = = = = = = = = = EPwm1Regs.CMPA.half.CMPA = Duty1A; // adjust duty for output EPWM1A EPwm1Regs.CMPB = Duty1B; // adjust duty for output EPWM1B

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CA CA CA

CB CB

TBCTR

EPWMxA

EPWMxB

TBPRD

value

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ePWM Submodules

Figure 28. Up-Down-Count, Dual Edge Symmetric Waveform, With Independent Modulation on EPWMxA

and EPWMxB — Complementary

A PWM period = 2 × TBPRD × T B Duty modulation for EPWMxA is set by CMPA, and is active low, i.e., low time duty proportional to CMPA C Duty modulation for EPWMxB is set by CMPB and is active high, i.e., high time duty proportional to CMPB D Outputs EPWMx can drive upper/lower (complementary) power switches E Dead-band = CMPB - CMPA (fully programmable edge placement by software). Note the dead-band module is also

available if the more classical edge delay method is required.

TBCLK

Example 6 contains a code sample showing initialization and run time for the waveforms in Figure 28. Use

the code in to define the headers.

Example 6. Code Sample for Figure 28

// Initialization Time // = = = = = = = = = = = = = = = = = = = = = = = = EPwm1Regs.TBPRD = 600; // Period = 2´600 TBCLK counts EPwm1Regs.CMPA.half.CMPA = 350; // Compare A = 350 TBCLK counts EPwm1Regs.CMPB = 400; // Compare B = 400 TBCLK counts EPwm1Regs.TBPHS = 0; // Set Phase register to zero EPwm1Regs.TBCTR = 0; // clear TB counter EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetric EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE; // Phase loading disabled EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW; EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE; EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1; // TBCLK = SYSCLKOUT EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV1; EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR = Zero EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR = Zero EPwm1Regs.AQCTLA.bit.CAU = AQ_SET; EPwm1Regs.AQCTLA.bit.CAD = AQ_CLEAR; EPwm1Regs.AQCTLB.bit.CBU = AQ_CLEAR; EPwm1Regs.AQCTLB.bit.CBD = AQ_SET; // Run Time // = = = = = = = = = = = = = = = = = = = = = = = = EPwm1Regs.CMPA.half.CMPA = Duty1A; // adjust duty for output EPWM1A EPwm1Regs.CMPB = Duty1B; // adjust duty for output EPWM1B

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Z P Z P

TBCTR

EPWMxA

CA CA

ePWM Submodules

Figure 29. Up-Down-Count, Dual Edge Asymmetric Waveform, With Independent Modulation on

EPWMxA—Active Low

A PWM period = 2 × TBPRD × TBCLK B Rising edge and falling edge can be asymmetrically positioned within a PWM cycle. This allows for pulse placement

techniques. C Duty modulation for EPWMxA is set by CMPA and CMPB. D Low time duty for EPWMxA is proportional to (CMPA + CMPB). E To change this example to active high, CMPA and CMPB actions need to be inverted (i.e., Set ! Clear and Clear Set). F Duty modulation for EPWMxB is fixed at 50% (utilizes spare action resources for EPWMxB)

Example 7 contains a code sample showing initialization and run time for the waveforms in Figure 29. Use

the code in to define the headers.

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Example 7. Code Sample for Figure 29

// Initialization Time // = = = = = = = = = = = = = = = = = = = = = = = = EPwm1Regs.TBPRD = 600; // Period = 2 ´ 600 TBCLK counts EPwm1Regs.CMPA.half.CMPA = 250; // Compare A = 250 TBCLK counts EPwm1Regs.CMPB = 450; // Compare B = 450 TBCLK counts EPwm1Regs.TBPHS = 0; // Set Phase register to zero EPwm1Regs.TBCTR = 0; // clear TB counter EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetric EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE; // Phase loading disabled EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW; EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE; EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1; // TBCLK = SYSCLKOUT EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV1; EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR = Zero EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR = Zero EPwm1Regs.AQCTLA.bit.CAU = AQ_SET; EPwm1Regs.AQCTLA.bit.CBD = AQ_CLEAR; EPwm1Regs.AQCTLB.bit.ZRO = AQ_CLEAR; EPwm1Regs.AQCTLB.bit.PRD = AQ_SET; // Run Time // = = = = = = = = = = = = = = = = = = = = = = = = EPwm1Regs.CMPA.half.CMPA = EdgePosA; // adjust duty for output EPWM1A only EPwm1Regs.CMPB = EdgePosB;

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CTR = CMPB

CTR = CMPA

CTR_Dir

CTR = 0

CTR = PRD

Dead Band

(DB)

Counter

Compare

(CC)

Action

Qualifier

(AQ)

EPWMxA

EPWMxB

CTR = CMPB

CTR = 0

EPWMxINT

EPWMxSOCA

EPWMxSOCB

EPWMxA

EPWMxB

TZ1 to TZ6

CTR = CMPA

Time-Base

(TB)

CTR = PRD

CTR = 0

CTR_Dir

EPWMxSYNCI

EPWMxSYNCO

EPWMxTZINT

PWM-

chopper

(PC)

Event

Trigger

and

Interrupt

(ET)

Trip Zone (TZ)

GPIO

MUX

ADC

PIE

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2.5 Dead-Band Generator (DB) Submodule

Figure 30 illustrates the dead-band submodule within the ePWM module.

Figure 30. Dead_Band Submodule

ePWM Submodules

2.5.1 Purpose of the Dead-Band Submodule

The "Action-qualifier (AQ) Module" section discussed how it is possible to generate the required dead-band by having full control over edge placement using both the CMPA and CMPB resources of the ePWM module. However, if the more classical edge delay-based dead-band with polarity control is required, then the dead-band submodule described here should be used.

The key functions of the dead-band module are:

• Generating appropriate signal pairs (EPWMxA and EPWMxB) with dead-band relationship from a single EPWMxA input

• Programming signal pairs for: – Active high (AH)

– Active low (AL) – Active high complementary (AHC) – Active low complementary (ALC)

• Adding programmable delay to rising edges (RED)

• Adding programmable delay to falling edges (FED)

• Can be totally bypassed from the signal path (note dotted lines in diagram)

2.5.2 Controlling and Monitoring the Dead-Band Submodule

The dead-band submodule operation is controlled and monitored via the following registers:

Table 13. Dead-Band Generator Submodule Registers

DBCTL 0x000F No Dead-Band Control Register DBRED 0x0010 No Dead-Band Rising Edge Delay Count Register DBFED 0x0011 No Dead-Band Falling Edge Delay Count Register

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RED

OutIn

Risingedge

delay

(10-bit

counter)

(10-bit

counter)

delay

Fallingedge

In Out

FED

EPWMxA

EPWMxB

DBCTL[POLSEL] DBCTL[OUT_MODE]

DBCTL[IN_MODE]

EPWMxA in

EPWMxBin

ePWM Submodules

2.5.3 Operational Highlights for the Dead-Band Submodule

The following sections provide the operational highlights. The dead-band submodule has two groups of independent selection options as shown in Figure 31.

• Input Source Selection: The input signals to the dead-band module are the EPWMxA and EPWMxB output signals from the

action-qualifier. In this section they will be referred to as EPWMxA In and EPWMxB In. Using the DBCTL[IN_MODE) control bits, the signal source for each delay, falling-edge or rising-edge, can be selected:

– EPWMxA In is the source for both falling-edge and rising-edge delay. This is the default mode. – EPWMxA In is the source for falling-edge delay, EPWMxB In is the source for rising-edge delay. – EPWMxA In is the source for rising edge delay, EPWMxB In is the source for falling-edge delay. – EPWMxB In is the source for both falling-edge and rising-edge delay.

• Output Mode Control: The output mode is configured by way of the DBCTL[OUT_MODE] bits. These bits determine if the

falling-edge delay, rising-edge delay, neither, or both are applied to the input signals.

• Polarity Control: The polarity control (DBCTL[POLSEL]) allows you to specify whether the rising-edge delayed signal

and/or the falling-edge delayed signal is to be inverted before being sent out of the dead-band submodule.

Figure 31. Configuration Options for the Dead-Band Submodule

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Although all combinations are supported, not all are typical usage modes. Table 14 documents some classical dead-band configurations. These modes assume that the DBCTL[IN_MODE] is configured such that EPWMxA In is the source for both falling-edge and rising-edge delay. Enhanced, or non-traditional modes can be achieved by changing the input signal source. The modes shown in Table 14 fall into the following categories:

• Mode 1: Bypass both falling-edge delay (FED) and rising-edge delay (RED)

• Mode 2-5: Classical Dead-Band Polarity Settings:

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These represent typical polarity configurations that should address all the active high/low modes required by available industry power switch gate drivers. The waveforms for these typical cases are shown in Figure 32. Note that to generate equivalent waveforms to Figure 32, configure the action-qualifier submodule to generate the signal as shown for EPWMxA.

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Original

(outA)

Rising Edge

Delayed (RED)

Falling Edge

Delayed (FED)

Active High

(AHC)

Active Low

(ALC)

Active High

(AH)

Active Low

(AL)

RED

FED

Period

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• Mode 6: Bypass rising-edge-delay and Mode 7: Bypass falling-edge-delay

Figure 32 shows waveforms for typical cases where 0% < duty < 100%.

ePWM Submodules

Finally the last two entries in Table 14 show combinations where either the falling-edge-delay (FED) or rising-edge-delay (RED) blocks are bypassed.

Table 14. Classical Dead-Band Operating Modes

Mode Mode Description

1 EPWMxA and EPWMxB Passed Through (No Delay) X X 0 0 2 Active High Complementary (AHC) 1 0 1 1 3 Active Low Complementary (ALC) 0 1 1 1 4 Active High (AH) 0 0 1 1 5 Active Low (AL) 1 1 1 1

EPWMxA Out = EPWMxA In (No Delay)

6 0 or 1 0 or 1 0 1

EPWMxB Out = EPWMxA In with Falling Edge Delay EPWMxA Out = EPWMxA In with Rising Edge Delay

7 0 or 1 0 or 1 1 0

EPWMxB Out = EPWMxB In with No Delay

DBCTL[POLSEL] DBCTL[OUT_MODE]

S3 S2 S1 S0

Figure 32. Dead-Band Waveforms for Typical Cases (0% < Duty < 100%)

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ePWM Submodules

The dead-band submodule supports independent values for rising-edge (RED) and falling-edge (FED) delays. The amount of delay is programmed using the DBRED and DBFED registers. These are 10-bit registers and their value represents the number of time-base clock, TBCLK, periods a signal edge is delayed by. For example, the formula to calculate falling-edge-delay and rising-edge-delay are:

FED = DBFED × T RED = DBRED × T

Where T

TBCLK

For convenience, delay values for various TBCLK options are shown in Table 15.

Dead-Band Value Dead-Band Delay in μS

DBFED, DBRED TBCLK = SYSCLKOUT/1 TBCLK = SYSCLKOUT /2 TBCLK = SYSCLKOUT/4

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TBCLK

is the period of TBCLK, the prescaled version of SYSCLKOUT.

Table 15. Dead-Band Delay Values in μS as a Function of DBFED and DBRED

1 0.01 μS 0.02 μS 0.04 μS 5 0.05 μS 0.10 μS 0.20 μS

10 0.10 μS 0.20 μS 0.40 μS 100 1.00 μS 2.00 μS 4.00 μS 200 2.00 μS 4.00 μS 8.00 μS 300 3.00 μS 6.00 μS 12.00 μS 400 4.00 μS 8.00 μS 16.00 μS 500 5.00 μS 10.00 μS 20.00 μS 600 6.00 μS 12.00 μS 24.00 μS 700 7.00 μS 14.00 μS 28.00 μS 800 8.00 μS 16.00 μS 32.00 μS 900 9.00 μS 18.00 μS 36.00 μS

1000 10.00 μS 20.00 μS 40.00 μS

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CTR = CMPB

CTR = CMPA

CTR_Dir

CTR = 0

CTR = PRD

Dead Band

(DB)

Counter

Compare

(CC)

Action

Qualifier

(AQ)

EPWMxB

EPWMxA

CTR = CMPB

CTR = 0

EPWMxINT

EPWMxSOCA

EPWMxSOCB

EPWMxA

EPWMxB

TZ1 to TZ6

CTR = CMPA

Time-Base

(TB)

CTR = PRD

CTR = 0

CTR_Dir

EPWMxSYNCI

EPWMxSYNCO

EPWMxTZINT

PWM-

chopper

(PC)

Event

Trigger

and

Interrupt

(ET)

Trip Zone (TZ)

GPIO

MUX

ADC

PIE

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2.6 PWM-Chopper (PC) Submodule

Figure 33 illustrates the PWM-chopper (PC) submodule within the ePWM module.

Figure 33. PWM-Chopper Submodule

The PWM-chopper submodule allows a high-frequency carrier signal to modulate the PWM waveform generated by the action-qualifier and dead-band submodules. This capability is important if you need pulse transformer-based gate drivers to control the power switching elements.

ePWM Submodules

2.6.1 Purpose of the PWM-Chopper Submodule

The key functions of the PWM-chopper submodule are:

• Programmable chopping (carrier) frequency

• Programmable pulse width of first pulse

• Programmable duty cycle of second and subsequent pulses

• Can be fully bypassed if not required

2.6.2 Controlling the PWM-Chopper Submodule

The PWM-chopper submodule operation is controlled via the registers in Table 16.

Table 16. PWM-Chopper Submodule Registers

mnemonic Address offset Shadowed Description

PCCTL 0x001E No PWM-chopper Control Register

2.6.3 Operational Highlights for the PWM-Chopper Submodule

Figure 34 shows the operational details of the PWM-chopper submodule. The carrier clock is derived from

SYSCLKOUT. Its frequency and duty cycle are controlled via the CHPFREQ and CHPDUTY bits in the PCCTL register. The one-shot block is a feature that provides a high energy first pulse to ensure hard and fast power switch turn on, while the subsequent pulses sustain pulses, ensuring the power switch remains on. The one-shot width is programmed via the OSHTWTH bits. The PWM-chopper submodule can be fully disabled (bypassed) via the CHPEN bit.

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Start

Clk

One shot

Pulse-width

PCCTL

[OSHTWTH]

PWMA_ch

Bypass

Dividerand dutycontrol

PSCLK

OSHT

EPWMxA

PCCTL [CHPEN]

EPWMxA

/8SYSCLKOUT

Pulse-width

Start

shot

Clk

One

PCCTL

[OSHTWTH]

OSHT

PCCTL[CHPFREQ]

PCCTL[CHPDUTY]

PWMB_ch

Bypass

EPWMxB

PSCLK

ePWM Submodules

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Figure 34. PWM-Chopper Submodule Operational Details

2.6.4 Waveforms

Figure 35 shows simplified waveforms of the chopping action only; one-shot and duty-cycle control are not

shown. Details of the one-shot and duty-cycle control are discussed in the following sections.

Figure 35. Simple PWM-Chopper Submodule Waveforms Showing Chopping Action Only

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PSCLK

OSHT

EPWMxA in

Prog. pulse width (OSHTWTH)

Start OSHT pulse

Sustaining pulses

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ePWM Submodules

2.6.4.1 One-Shot Pulse

The width of the first pulse can be programmed to any of 16 possible pulse width values. The width or period of the first pulse is given by:

Where T

1stpulse

= T

SYSCLKOUT

× 8 × OSHTWTH

is the period of the system clock (SYSCLKOUT) and OSHTWTH is the four control bits

(value from 1 to 16)

Figure 36 shows the first and subsequent sustaining pulses and Table 7.3 gives the possible pulse width

values for a SYSCLKOUT = 100 MHz.

Figure 36. PWM-Chopper Submodule Waveforms Showing the First Pulse and Subsequent Sustaining

Pulses

Table 17. Possible Pulse Width Values for SYSCLKOUT

= 100 MHz

OSHTWTHz Pulse Width

(hex) (nS)

0 80 1 160 2 240 3 320 4 400 5 480 6 560 7 640 8 720

9 800 A 880 B 960 C 1040 D 1120 E 1200 F 1280

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1/8

2/8

3/8

4/8

5/8

6/8

7/8

PSCLK

12.5%

25%

37.5%

50%

62.5%

75%

87.5%

PSCLK Period

PSCLK

period

ePWM Submodules

2.6.4.2 Duty Cycle Control

Pulse transformer-based gate drive designs need to comprehend the magnetic properties or characteristics of the transformer and associated circuitry. Saturation is one such consideration. To assist the gate drive designer, the duty cycles of the second and subsequent pulses have been made programmable. These sustaining pulses ensure the correct drive strength and polarity is maintained on the power switch gate during the on period, and hence a programmable duty cycle allows a design to be tuned or optimized via software control.

Figure 37 shows the duty cycle control that is possible by programming the CHPDUTY bits. One of seven

possible duty ratios can be selected ranging from 12.5% to 87.5%.

Figure 37. PWM-Chopper Submodule Waveforms Showing the Pulse Width (Duty Cycle) Control of

Sustaining Pulses

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CTR = CMPB

CTR = CMPA

CTR_Dir

CTR = 0

CTR = PRD

Dead Band

(DB)

Counter

Compare

(CC)

Action

Qualifier

(AQ)

EPWMxA

EPWMxB

CTR = CMPB

CTR = 0

EPWMxINT

EPWMxSOCA

EPWMxSOCB

EPWMxA

EPWMxB

TZ1 to TZ6

CTR = CMPA

Time-Base

(TB)

CTR = PRD

CTR = 0

CTR_Dir

EPWMxSYNCI

EPWMxSYNCO

EPWMxTZINT

PWM-

chopper

(PC)

Event

Trigger

and

Interrupt

(ET)

Trip Zone (TZ)

GPIO

MUX

ADC

PIE

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2.7 Trip-Zone (TZ) Submodule

Figure 38 shows how the trip-zone (TZ) submodule fits within the ePWM module.

Each ePWM module is connected to six TZn signals (TZ1 to TZ6) that are sourced from the GPIO MUX. These signals indicate external fault or trip conditions, and the ePWM outputs can be programmed to respond accordingly when faults occur.

ePWM Submodules

Figure 38. Trip-Zone Submodule

2.7.1 Purpose of the Trip-Zone Submodule

The key functions of the Trip-Zone submodule are:

• Trip inputs TZ1 to TZ6 can be flexibly mapped to any ePWM module.

• Upon a fault condition, outputs EPWMxA and EPWMxB can be forced to one of the following: – High

– Low – High-impedance – No action taken

• Support for one-shot trip (OSHT) for major short circuits or over-current conditions.

• Support for cycle-by-cycle tripping (CBC) for current limiting operation.

• Each trip-zone input pin can be allocated to either one-shot or cycle-by-cycle operation.

• Interrupt generation is possible on any trip-zone pin .

• Software-forced tripping is also supported.

• The trip-zone submodule can be fully bypassed if it is not required.

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ePWM Submodules

2.7.2 Controlling and Monitoring the Trip-Zone Submodule

The trip-zone submodule operation is controlled and monitored through the following registers:

Table 18. Trip-Zone Submodule Registers

TZSEL 0x0012 No Trip-Zone Select Register

reserved 0x0013

TZCTL 0x0014 No Trip-Zone Control Register

TZEINT 0x0015 No Trip-Zone Enable Interrupt Register

TZFLG 0x0016 No Trip-Zone Flag Register TZCLR 0x0017 No Trip-Zone Clear Register TZFRC 0x0018 No Trip-Zone Force Register

(1)

All trip-zone registers are EALLOW protected and can be modified only after executing the EALLOW instruction. For more information, see the device-specific version of the System Control and Interrupts Reference Guide listed in Section 1.

2.7.3 Operational Highlights for the Trip-Zone Submodule

The following sections describe the operational highlights and configuration options for the trip-zone submodule.

The trip-zone signals at pins TZ1 to TZ6 (also collectively referred to as TZn) are active low input signals. When one of these pins goes low, it indicates that a trip event has occurred. Each ePWM module can be individually configured to ignore or use each of the trip-zone pins . Which trip-zone pins are used by a particular ePWM module is determined by the TZSEL register for that specific ePWM module. The trip-zone signals may or may not be synchronized to the system clock (SYSCLKOUT) and digitally filtered within the GPIO MUX block. A minimum 1 SYSCLKOUT low pulse on TZn inputs is sufficient to trigger a fault condition in the ePWM module. The asynchronous trip makes sure that if clocks are missing for any reason, the outputs can still be tripped by a valid event present on TZn inputs , providing the GPIO is appropriately configured . For more information, see the GPIO section of the device-specific version of the System Control and Interrupts Reference Guide listed in Related Documentation From Texas Instruments.

Each TZn input can be individually configured to provide either a cycle-by-cycle or one-shot trip event for an ePWM module. This configuration is determined by the TZSEL[CBCn], and TZSEL[OSHTn] control bits (where n corresponds to the trip pin) respectively.

• Cycle-by-Cycle (CBC): When a cycle-by-cycle trip event occurs, the action specified in the TZCTL register is carried out

immediately on the EPWMxA and/or EPWMxB output. Table 19 lists the possible actions. In addition, the cycle-by-cycle trip event flag (TZFLG[CBC]) is set and a EPWMx_TZINT interrupt is generated if it is enabled in the TZEINT register and PIE peripheral.

The specified condition on the pins is automatically cleared when the ePWM time-base counter reaches zero (TBCTR = 0x0000) if the trip event is no longer present. Therefore, in this mode, the trip event is cleared or reset every PWM cycle. The TZFLG[CBC] flag bit will remain set until it is manually cleared by writing to the TZCLR[CBC] bit. If the cycle-by-cycle trip event is still present when the TZFLG[CBC] bit is cleared, then it will again be immediately set.

• One-Shot (OSHT): When a one-shot trip event occurs, the action specified in the TZCTL register is carried out

immediately on the EPWMxA and/or EPWMxB output. Table 19 lists the possible actions. In addition, the one-shot trip event flag (TZFLG[OST]) is set and a EPWMx_TZINT interrupt is generated if it is enabled in the TZEINT register and PIE peripheral. The one-shot trip condition must be cleared manually by writing to the TZCLR[OST] bit.

The action taken when a trip event occurs can be configured individually for each of the ePWM output pins by way of the TZCTL[TZA] and TZCTL[TZB] register bits fields. One of four possible actions, shown in Table 19, can be taken on a trip event.

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ePWM Submodules

Table 19. Possible Actions On a Trip Event

TZCTL[TZA] EPWMxA Comment

and/or and/or

TZCTL[TZB] EPWMxB

0,0 High-Impedance Tripped 0,1 Force to High State Tripped 1,0 Force to Low State Tripped 1,1 No Change Do Nothing.

No change is made to the output.

Example 8. Trip-Zone Configurations

Scenario A:

A one-shot trip event on TZ1 pulls both EPWM1A, EPWM1B low and also forces EPWM2A and EPWM2B high.

• Configure the ePWM1 registers as follows: – TZSEL[OSHT1] = 1: enables TZ1 as a one-shot event source for ePWM1

– TZCTL[TZA] = 2: EPWM1A will be forced low on a trip event. – TZCTL[TZB] = 2: EPWM1B will be forced low on a trip event.

• Configure the ePWM2 registers as follows: – TZSEL[OSHT1] = 1: enables TZ1 as a one-shot event source for ePWM2

– TZCTL[TZA] = 1: EPWM2A will be forced high on a trip event. – TZCTL[TZB] = 1: EPWM2B will be forced high on a trip event.

Scenario B:

A cycle-by-cycle event on TZ5 pulls both EPWM1A, EPWM1B low. A one-shot event on TZ1 or TZ6 puts EPWM2A into a high impedance state.

• Configure the ePWM1 registers as follows: – TZSEL[CBC5] = 1: enables TZ5 as a one-shot event source for ePWM1

– TZCTL[TZA] = 2: EPWM1A will be forced low on a trip event. – TZCTL[TZB] = 2: EPWM1B will be forced low on a trip event.

• Configure the ePWM2 registers as follows: – TZSEL[OSHT1] = 1: enables TZ1 as a one-shot event source for ePWM2

– TZSEL[OSHT6] = 1: enables TZ6 as a one-shot event source for ePWM2 – TZCTL[TZA] = 0: EPWM2A will be put into a high-impedance state on a trip event. – TZCTL[TZB] = 3: EPWM2B will ignore the trip event.

2.7.4 Generating Trip Event Interrupts

Figure 39 and Figure 40 illustrate the trip-zone submodule control and interrupt logic, respectively.

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Latch

cyc−by-cyc

mode

(CBC)

CTR=zero

TZFRC[CBC]

TZ1 TZ2 TZ3 TZ4 TZ5 TZ6

Sync

Clear

Set

one-shot

Latch

(OSHT)

mode

Clear

TZSEL[CBC1toCBC6]

TZCLR[OST]

TZSEL[OSHT1toOSHT6]

TZFRC[OSHT]

Sync

TZ6

TZ5

TZ4

TZ3

TZ2

TZ1

Trip

logic

Trip

CBC tripevent

OSHT tripevent

EPWMxA EPWMxB

TZCTL[TZB] TZCTL[TZA]

AsyncTrip

Set

Clear

TZFLG[CBC]

TZCLR[CBC]

Set

Clear

TZFLG[OST]

ePWM Submodules

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Figure 39. Trip-Zone Submodule Mode Control Logic

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Generate

interrupt

pulsewhen

input=1

Clear

Set

TZCLR[INT]

EPWMx_TZINT

(PIE)

Latch

Clear

Set

Clear

Set

Latch

TZFLG[CBC]

TZFLG[OST]

TZEINT[CBC]

TZCLR[CBC]

CBC tripevent

TZEINT[OST]

OSHT tripevent

TZCLR[OST]

TZFLG[INT]

CTR=CMPB

CTR=CMPA

CTR_Dir

CTR=0

CTR=PRD

Dead

Band

(DB)

Counter

Compare

(CC)

Action

Qualifier

(AQ)

EPWMA

EPWMB

CTR=CMPB

CTR=0

EPWMxINT

EPWMxSOCA

EPWMxSOCB

EPWMxA

EPWMxB

TZ1

toTZ6

CTR=CMPA

Time-Base

(TB)

CTR=PRD

CTR=0

CTR_Dir

EPWMxSYNCI

EPWMxSYNCO

EPWMxTZINT

PWM-

chopper

(PC)

Event

Trigger

and

Interrupt

(ET)

Trip

Zone

(TZ)

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Figure 40. Trip-Zone Submodule Interrupt Logic

2.8 Event-Trigger (ET) Submodule

The key functions of the event-trigger submodule are:

• Receives event inputs generated by the time-base and counter-compare submodules

• Uses the time-base direction information for up/down event qualification

• Uses prescaling logic to issue interrupt requests and ADC start of conversion at: – Every event

– Every second event – Every third event

• Provides full visibility of event generation via event counters and flags

• Allows software forcing of Interrupts and ADC start of conversion

The event-trigger submodule manages the events generated by the time-base submodule, the counter-compare submodule, and the digital-compare submodule to generate an interrupt to the CPU and/or a start of conversion pulse to the ADC when a selected event occurs. Figure 41 illustrates where the event-trigger submodule fits within the ePWM system.

ePWM Submodules

2.8.1 Operational Overview of the Event-Trigger Submodule

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Figure 41. Event-Trigger Submodule

The following sections describe the event-trigger submodule's operational highlights.

EXTSOCAG1

POLSEL

PulseStretcher

32HSPCLKCyclesW

ideandThentoChipPins

EXTSOCAG1

ePWM2

ePWM2SOCA

ePWM2SOCB

ePWM1

ePWM1SOCA

ePWM1SOCB

ePWM3

ePWM3SOCA

ePWM3SOCB

ePWM4

ePWM4SOCA

ePWM4SOCB

EXTSOCAG4

POLSEL

EXTSOCAG4

ePWM6

ePWM6SOCA

ePWM6SOCB

ePWM5

ePWM5SOCA

ePWM5SOCB

ePWM7

ePWM7SOCA

ePWM7SOCB

ePWM8

ePWM8SOCA

ePWM4SOCB

EXTSOCBG1

POLSEL

EXTSOCSBG1

EXTSOCBG4

POLSEL

EXTSOCBG4

ePWM9

ePWM9SOCA

ePWM9SOCB

EXTSOCAG7

POLSEL

EXTSOCAG7

EXTSOCBG7

POLSEL

EXTSOCBG7

ePWM Submodules

Each ePWM module has one interrupt request line connected to the PIE and two start of conversion signals (one for each sequencer) connected to the ADC module. As shown in Figure 42, ADC start of conversion for all ePWM modules are ORed together and hence multiple modules can initiate an ADC start of conversion. If two requests occur on one start of conversion line, then only one will be recognized by the ADC.

Figure 42. Event-Trigger Submodule Inter-Connectivity of ADC Start of Conversion

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The event-trigger submodule monitors various event conditions (the left side inputs to event-trigger submodule shown in Figure 43) and can be configured to prescale these events before issuing an Interrupt request or an ADC start of conversion. The event-trigger prescaling logic can issue Interrupt requests and ADC start of conversion at:

• Every event

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PIE

Event Trigger Module Logic

CTR=Zero

CTR=PRD

CTR=CMPA

EPWMxINTn

CTR_dir

Direction

qualifier

CTRU=CMPA

ETSEL reg

EPWMxSOCA

EPWMxSOCB

ADC

clear

count

clear

count

clear

CTRD=CMPA CTRU=CMPB CTRD=CMPB

ETPS reg

ETFLG reg

ETCLR reg

ETFRC reg

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• Every second event

• Every third event

The key registers used to configure the event-trigger submodule are shown in Table 20:

ePWM Submodules

Figure 43. Event-Trigger Submodule Showing Event Inputs and Prescaled Outputs

Table 20. Event-Trigger Submodule Registers

ETSEL 0x0019 No Event-trigger Selection Register

ETPS 0x001A No Event-trigger Prescale Register ETFLG 0x001B No Event-trigger Flag Register ETCLR 0x001C No Event-trigger Clear Register ETFRC 0x001D No Event-trigger Force Register

• ETSEL—This selects which of the possible events will trigger an interrupt or start an ADC conversion

• ETPS—This programs the event prescaling options mentioned above.

• ETFLG—These are flag bits indicating status of the selected and prescaled events.

• ETCLR—These bits allow you to clear the flag bits in the ETFLG register via software.

• ETFRC—These bits allow software forcing of an event. Useful for debugging or s/w intervention. A more detailed look at how the various register bits interact with the Interrupt and ADC start of

conversion logic are shown in Figure 44, Figure 45, and Figure 46.

Figure 44 shows the event-trigger's interrupt generation logic. The interrupt-period (ETPS[INTPRD]) bits

specify the number of events required to cause an interrupt pulse to be generated. The choices available are:

• Do not generate an interrupt.

• Generate an interrupt on every event

• Generate an interrupt on every second event

• Generate an interrupt on every third event Which event can cause an interrupt is configured by the interrupt selection (ETSEL[INTSEL]) bits. The

event can be one of the following:

• Time-base counter equal to zero (TBCTR = 0x0000).

• Time-base counter equal to period (TBCTR = TBPRD).

• Time-base counter equal to the compare A register (CMPA) when the timer is incrementing.

• Time-base counter equal to the compare A register (CMPA) when the timer is decrementing.

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Latch

Generate

interrupt

pulse when

input = 1

2-bit

Counter

Set

Clear

Clear CNT

Inc CNT

ETPS[INTCNT]

ETPS[INTPRD]

ETCLR[INT]

EPWMxINT

ETFRC[INT]

ETSEL[INT]

ETFLG[INT]

ETSEL[INTSEL]

000 001 010 011 100 101

111

101

0 CTRU=CMPA CTRD=CMPA CTRU=CMPB CTRD=CMPB

CTR=Zero CTR=PRD

ePWM Submodules

• Time-base counter equal to the compare B register (CMPB) when the timer is incrementing.

• Time-base counter equal to the compare B register (CMPB) when the timer is decrementing. The number of events that have occurred can be read from the interrupt event counter (ETPS[INTCNT])

register bits. That is, when the specified event occurs the ETPS[INTCNT] bits are incremented until they reach the value specified by ETPS[INTPRD]. When ETPS[INTCNT] = ETPS[INTPRD] the counter stops counting and its output is set. The counter is only cleared when an interrupt is sent to the PIE.

When ETPS[INTCNT] reaches ETPS[INTPRD] the following behaviors will occur:

• If interrupts are enabled, ETSEL[INTEN] = 1 and the interrupt flag is clear, ETFLG[INT] = 0, then an interrupt pulse is generated and the interrupt flag is set, ETFLG[INT] = 1, and the event counter is cleared ETPS[INTCNT] = 0. The counter will begin counting events again.

• If interrupts are disabled, ETSEL[INTEN] = 0, or the interrupt flag is set, ETFLG[INT] = 1, the counter stops counting events when it reaches the period value ETPS[INTCNT] = ETPS[INTPRD].

• If interrupts are enabled, but the interrupt flag is already set, then the counter will hold its output high until the ENTFLG[INT] flag is cleared. This allows for one interrupt to be pending while one is serviced.

Writing to the INTPRD bits will automatically clear the counter INTCNT = 0 and the counter output will be reset (so no interrupts are generated). Writing a 1 to the ETFRC[INT] bit will increment the event counter INTCNT. The counter will behave as described above when INTCNT = INTPRD. When INTPRD = 0, the counter is disabled and hence no events will be detected and the ETFRC[INT] bit is also ignored.

The above definition means that you can generate an interrupt on every event, on every second event, or on every third event. An interrupt cannot be generated on every fourth or more events.

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Figure 44. Event-Trigger Interrupt Generator

Figure 45 shows the operation of the event-trigger's start-of-conversion-A (SOCA) pulse generator. The

ETPS[SOCACNT] counter and ETPS[SOCAPRD] period values behave similarly to the interrupt generator except that the pulses are continuously generated. That is, the pulse flag ETFLG[SOCA] is latched when a pulse is generated, but it does not stop further pulse generation. The enable/disable bit ETSEL[SOCAEN] stops pulse generation, but input events can still be counted until the period value is reached as with the interrupt generation logic. The event that will trigger an SOCA and SOCB pulse can be configured separately in the ETSEL[SOCASEL] and ETSEL[SOCBSEL] bits. The possible events are the same events that can be specified for the interrupt generation logic .

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Latch

Generate

SOC pulse when

input=1

2-bit

Counter

Set

Clear

ClearCNT

IncCNT

ETPS[SOCACNT]

ETPS[SOCAPRD]

ETCLR[SOCA]

SOCA

ETFRC[SOCA]

ETSEL[SOCAEN]

ETFLG[SOCA]

ETSEL[SOCASEL]

000 001 010 011 100 101

111

101

0 CTRU=CMPA CTRD=CMPA CTRU=CMPB CTRD=CMPB

CTR=Zero CTR=PRD

Latch

Generate

SOC pulse when

input=1

2-bit

Counter

Set

Clear

ClearCNT

IncCNT

ETPS[SOCBCNT]

ETPS[SOCBPRD]

ETCLR[SOCB]

SOCB

ETFRC[SOCB]

ETSEL[SOCBEN]

ETFLG[SOCB]

ETSEL[SOCBSEL]

000 001 010 011 100 101

111

101

0 CTRU=CMPA CTRD=CMPA CTRU=CMPB CTRD=CMPB

CTR=Zero CTR=PRD

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Figure 46 shows the operation of the event-trigger's start-of-conversion-B (SOCB) pulse generator. The

event-trigger's SOCB pulse generator operates the same way as the SOCA.

ePWM Submodules

Figure 45. Event-Trigger SOCA Pulse Generator

Figure 46. Event-Trigger SOCB Pulse Generator

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CTR = 0

CTR=CMPB

SyncOut

Phase reg

EPWMxA EPWMxB

SyncIn

Φ=0°

Applications to Power Topologies

3 Applications to Power Topologies

An ePWM module has all the local resources necessary to operate completely as a standalone module or to operate in synchronization with other identical ePWM modules.

3.1 Overview of Multiple Modules

Previously in this user's guide, all discussions have described the operation of a single module. To facilitate the understanding of multiple modules working together in a system, the ePWM module described in reference is represented by the more simplified block diagram shown in Figure 47. This simplified ePWM block shows only the key resources needed to explain how a multiswitch power topology is controlled with multiple ePWM modules working together.

Figure 47. Simplified ePWM Module

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3.2 Key Configuration Capabilities

The key configuration choices available to each module are as follows:

• Options for SyncIn – Load own counter with phase register on an incoming sync strobe—enable (EN) switch closed

– Do nothing or ignore incoming sync strobe—enable switch open – Sync flow-through - SyncOut connected to SyncIn – Master mode, provides a sync at PWM boundaries—SyncOut connected to CTR = PRD – Master mode, provides a sync at any programmable point in time—SyncOut connected to CTR =

CMPB

– Module is in standalone mode and provides No sync to other modules—SyncOut connected to X

(disabled)

• Options for SyncOut – Sync flow-through - SyncOut connected to SyncIn

– Master mode, provides a sync at PWM boundaries—SyncOut connected to CTR = PRD – Master mode, provides a sync at any programmable point in time—SyncOut connected to CTR =

CMPB

– Module is in standalone mode and provides No sync to other modules—SyncOut connected to X

(disabled)

For each choice of SyncOut, a module may also choose to load its own counter with a new phase value on a SyncIn strobe input or choose to ignore it, i.e., via the enable switch. Although various combinations are possible, the two most common—master module and slave module modes—are shown in Figure 48.

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CTR=0

CTR=CMPB

SyncOut

Phase reg

Ext SyncIn

(optional)

EPWM1A

EPWM1B

SyncOut

Phase reg

CTR=CMPB

CTR=0

EPWM2B

EPWM2A

Slave

Master

SyncIn

Φ=0°

www.ti.com

Applications to Power Topologies

Figure 48. EPWM1 Configured as a Typical Master, EPWM2 Configured as a Slave

3.3 Controlling Multiple Buck Converters With Independent Frequencies

One of the simplest power converter topologies is the buck. A single ePWM module configured as a master can control two buck stages with the same PWM frequency. If independent frequency control is required for each buck converter, then one ePWM module must be allocated for each converter stage.

Figure 49 shows four buck stages, each running at independent frequencies. In this case, all four ePWM

modules are configured as Masters and no synchronization is used. Figure 50 shows the waveforms generated by the setup shown in Figure 49; note that only three waveforms are shown, although there are four stages.

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CTR=zero

CTR=CMPB

SyncOut

Phase reg

Ext SyncIn (optional)

EPWM1A EPWM1B

SyncOut

Phase reg

CTR=CMPB

CTR=zero

EPWM2B

EPWM2A

Master2

Master1

SyncIn

CTR=zero

CTR=CMPB

SyncOut

EPWM3B

Phase reg

Master3

EPWM3A

Φ=X

CTR=zero

CTR=CMPB

SyncOut

EPWM4B

Phase reg

Master4

EPWM4A

Φ=X

Buck #1

Vout1Vin1

EPWM1A

Buck #2

Vin2

EPWM2A

Vout2

Buck #4

Buck #3

Vin3

EPWM4A

Vin4

EPWM3A

Vout3

Vout4

SyncIn

Applications to Power Topologies

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Figure 49. Control of Four Buck Stages. Here F

PWM1

≠ F

PWM2

≠ F

PWM3

≠ F

PWM4

NOTE: Θ = X indicates value in phase register is a "don't care"

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P CA CBAP CA P

Pulse center

EPWM1A

700 950

1200

P CA CB

P CA

700 1150

1400

EPWM2A

CA P

P CA P

500

650

800

EPWM3A

Indicates this event triggers an interrupt CB

Indicates this event triggers an ADC start of conversion

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Applications to Power Topologies

Figure 50. Buck Waveforms for Figure 49 (Note: Only three bucks shown here)

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Applications to Power Topologies

Example 9. Configuration for Example in Figure 50

//===================================================================== // (Note: code for only 3 modules shown) // Initialization Time //======================== // EPWM Module 1 config

EPwm1Regs.TBPRD = 1200; // Period = 1201 TBCLK counts EPwm1Regs.TBPHS.half.TBPHS = 0; // Set Phase register to zero EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP; // Asymmetrical mode EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE; // Phase loading disabled EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW; EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE; EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm1Regs.AQCTLA.bit.PRD = AQ_CLEAR; EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;

// EPWM Module 2 config

EPwm2Regs.TBPRD = 1400; // Period = 1401 TBCLK counts EPwm2Regs.TBPHS.half.TBPHS = 0; // Set Phase register to zero EPwm2Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP; // Asymmetrical mode EPwm2Regs.TBCTL.bit.PHSEN = TB_DISABLE; // Phase loading disabled EPwm2Regs.TBCTL.bit.PRDLD = TB_SHADOW; EPwm2Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE; EPwm2Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW; EPwm2Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW; EPwm2Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm2Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm2Regs.AQCTLA.bit.PRD = AQ_CLEAR; EPwm2Regs.AQCTLA.bit.CAU = AQ_SET;

// EPWM Module 3 config

EPwm3Regs.TBPRD = 800; // Period = 801 TBCLK counts EPwm3Regs.TBPHS.half.TBPHS = 0; // Set Phase register to zero EPwm3Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP; EPwm3Regs.TBCTL.bit.PHSEN = TB_DISABLE; // Phase loading disabled EPwm3Regs.TBCTL.bit.PRDLD = TB_SHADOW; EPwm3Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE; EPwm3Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW; EPwm3Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW; EPwm3Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm3Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm3Regs.AQCTLA.bit.PRD = AQ_CLEAR;

EPwm3Regs.AQCTLA.bit.CAU = AQ_SET; // // Run Time (Note: Example execution of one run-time instant) //=========================================================

EPwm1Regs.CMPA.half.CMPA = 700; // adjust duty for output EPWM1A

EPwm2Regs.CMPA.half.CMPA = 700; // adjust duty for output EPWM2A

EPwm3Regs.CMPA.half.CMPA = 500; // adjust duty for output EPWM3A

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CTR=zero

CTR=CMPB

Φ=0°

SyncOut

Phase reg

Ext SyncIn

(optional)

EPWM1A EPWM1B

SyncOut

Phase reg

CTR=CMPB

CTR=zero

Φ=X

EPWM2B

EPWM2A

Slave

Master

Buck #1

Vout1Vin1

EPWM1A

Buck #2

Vin2

EPWM1B

Vout2

Buck #4

Buck #3

Vin3

EPWM2B

Vin4

EPWM2A

Vout3

Vout4

SyncIn

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3.4 Controlling Multiple Buck Converters With Same Frequencies

If synchronization is a requirement, ePWM module 2 can be configured as a slave and can operate at integer multiple (N) frequencies of module 1. The sync signal from master to slave ensures these modules remain locked. Figure 51 shows such a configuration; Figure 52 shows the waveforms generated by the configuration.

Applications to Power Topologies

Figure 51. Control of Four Buck Stages. (Note: F

PWM2

= N x F

PWM1

)

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200

400

600

400

200

300

500

300

500

CA CA

Applications to Power Topologies

www.ti.com

Figure 52. Buck Waveforms for Figure 51 (Note: F

PWM2

= F

PWM1)

)

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Example 10. Code Snippet for Configuration in Figure 51

//======================== // EPWM Module 1 config

EPwm1Regs.TBPRD = 600; // Period = 1200 TBCLK counts EPwm1Regs.TBPHS.half.TBPHS = 0; // Set Phase register to zero EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetrical mode EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE; // Master module EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW; EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_CTR_ZERO; // Sync down-stream module EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm1Regs.AQCTLA.bit.CAU = AQ_SET; // set actions for EPWM1A EPwm1Regs.AQCTLA.bit.CAD = AQ_CLEAR; EPwm1Regs.AQCTLB.bit.CBU = AQ_SET; // set actions for EPWM1B EPwm1Regs.AQCTLB.bit.CBD = AQ_CLEAR;

// EPWM Module 2 config

EPwm2Regs.TBPRD = 600; // Period = 1200 TBCLK counts EPwm2Regs.TBPHS.half.TBPHS = 0; // Set Phase register to zero EPwm2Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetrical mode EPwm2Regs.TBCTL.bit.PHSEN = TB_ENABLE; // Slave module EPwm2Regs.TBCTL.bit.PRDLD = TB_SHADOW; EPwm2Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN; // sync flow-through EPwm2Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW; EPwm2Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW; EPwm2Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm2Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm2Regs.AQCTLA.bit.CAU = AQ_SET; // set actions for EPWM2A EPwm2Regs.AQCTLA.bit.CAD = AQ_CLEAR; EPwm2Regs.AQCTLB.bit.CBU = AQ_SET; // set actions for EPWM2B

EPwm2Regs.AQCTLB.bit.CBD = AQ_CLEAR; // // Run Time (Note: Example execution of one run-time instance) //===========================================================

EPwm1Regs.CMPA.half.CMPA = 400; // adjust duty for output EPWM1A EPwm1Regs.CMPB = 200; // adjust duty for output EPWM1B EPwm2Regs.CMPA.half.CMPA = 500; // adjust duty for output EPWM2A EPwm2Regs.CMPB = 300; // adjust duty for output EPWM2B

Applications to Power Topologies

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CTR=zero

CTR=CMPB

SyncOut

Phase reg

Ext SyncIn

(optional)

EPWM1A EPWM1B

SyncOut

Phase reg

CTR=CMPB

CTR=zero

EPWM2B

EPWM2A

Slave

Master

out1

EPWM1A

SyncIn

DC_bus

EPWM1B

EPWM2B

EPWM2A

DC_bus

out2

Φ=0°

Applications to Power Topologies

3.5 Controlling Multiple Half H-Bridge (HHB) Converters

Topologies that require control of multiple switching elements can also be addressed with these same

ePWM modules. It is possible to control a Half-H bridge stage with a single ePWM module. This control

can be extended to multiple stages. Figure 53 shows control of two synchronized Half-H bridge stages

where stage 2 can operate at integer multiple (N) frequencies of stage 1. Figure 54 shows the waveforms

generated by the configuration shown in Figure 53.

Module 2 (slave) is configured for Sync flow-through; if required, this configuration allows for a third Half-H

bridge to be controlled by PWM module 3 and also, most importantly, to remain in synchronization with

master module 1.

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Figure 53. Control of Two Half-H Bridge Stages (F

PWM2

= N x F

PWM1

)

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600

200

400

200

250

500

250

Pulse Center

ZIZ

Pulse Center

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Applications to Power Topologies

Figure 54. Half-H Bridge Waveforms for Figure 53 (Note: Here F

PWM2

= F

PWM1

)

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Applications to Power Topologies

Example 11. Code Snippet for Configuration in Figure 53

EPwm1Regs.TBPRD = 600; // Period = 1200 TBCLK counts

EPwm1Regs.TBPHS.half.TBPHS = 0; // Set Phase register to zero

EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetrical mode

EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE; // Master module

EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW;

EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_CTR_ZERO; // Sync down-stream module

EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;

EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;

EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero

EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero

EPwm1Regs.AQCTLA.bit.ZRO = AQ_SET; // set actions for EPWM1A

EPwm1Regs.AQCTLA.bit.CAU = AQ_CLEAR;

EPwm1Regs.AQCTLB.bit.ZRO = AQ_CLEAR; // set actions for EPWM1B

EPwm1Regs.AQCTLB.bit.CAD = AQ_SET; // EPWM Module 2 config

EPwm2Regs.TBPRD = 600; // Period = 1200 TBCLK counts

EPwm2Regs.TBPHS.half.TBPHS = 0; // Set Phase register to zero

EPwm2Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetrical mode

EPwm2Regs.TBCTL.bit.PHSEN = TB_ENABLE; // Slave module

EPwm2Regs.TBCTL.bit.PRDLD = TB_SHADOW;

EPwm2Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN; // sync flow-through

EPwm2Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;

EPwm2Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;

EPwm2Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero

EPwm2Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero

EPwm2Regs.AQCTLA.bit.ZRO = AQ_SET; // set actions for EPWM1A

EPwm2Regs.AQCTLA.bit.CAU = AQ_CLEAR;

EPwm2Regs.AQCTLB.bit.ZRO = AQ_CLEAR; // set actions for EPWM1B

EPwm2Regs.AQCTLB.bit.CAD = AQ_SET; //============================================================

EPwm1Regs.CMPA.half.CMPA = 400; // adjust duty for output EPWM1A & EPWM1B

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EPwm1Regs.CMPB = 200; // adjust point-in-time for ADCSOC trigger

EPwm2Regs.CMPA.half.CMPA = 500; // adjust duty for output EPWM2A & EPWM2B

EPwm2Regs.CMPB = 250; // adjust point-in-time for ADCSOC trigger

3.6 Controlling Dual 3-Phase Inverters for Motors (ACI and PMSM)

The idea of multiple modules controlling a single power stage can be extended to the 3-phase Inverter

case. In such a case, six switching elements can be controlled using three PWM modules, one for each

leg of the inverter. Each leg must switch at the same frequency and all legs must be synchronized. A

master + two slaves configuration can easily address this requirement. Figure 55 shows how six PWM

modules can control two independent 3-phase Inverters; each running a motor.

As in the cases shown in the previous sections, we have a choice of running each inverter at a different

frequency (module 1 and module 4 are masters as in Figure 55), or both inverters can be synchronized by

using one master (module 1) and five slaves. In this case, the frequency of modules 4, 5, and 6 (all equal)

can be integer multiples of the frequency for modules 1, 2, 3 (also all equal).

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Φ=0°

CTR=zero

CTR=CMPB

SyncOut

Phase reg

Ext SyncIn

(optional)

EPWM1A EPWM1B

SyncOut

Phase reg

CTR=CMPB

CTR=zero

EPWM2B

EPWM2A

Slave

Master

EPWM1A

EPWM1B

EPWM2A

EPWM2B EPWM3B

EPWM3A

VAB

VCD

VEF

3 phase motor

EPWM4B EPWM5B

VAB

EPWM4A

VCD

EPWM5A

EPWM6B

3 phase motor

VEF

EPWM6A

3 phase inverter #1

3 phase inverter #2

CTR=zero

CTR=CMPB

Phase reg

Slave

SyncOut

EPWM3B

EPWM3A

Phase reg

CTR=CMPB

CTR=zero

Slave

SyncOut

EPWM4A EPWM4B

SyncOut

CTR=zero

CTR=CMPB

Phase reg

CTR=CMPB

CTR=zero

Slave

SyncIn

EPWM6B

EPWM6A

SyncOut

EPWM5A EPWM5B

Φ=0°

SyncIn

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Applications to Power Topologies

Figure 55. Control of Dual 3-Phase Inverter Stages as Is Commonly Used in Motor Control

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RED

FED

RED

FED

EPWM1A

Φ2=0

Φ3=0

800

500

600 600

700

CA CA CA CA

Applications to Power Topologies

Figure 56. 3-Phase Inverter Waveforms for Figure 55 (Only One Inverter Shown)

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Example 12. Code Snippet for Configuration in Figure 55

//===================================================================== // Configuration //===================================================================== // Initialization Time //========================// EPWM Module 1 config

EPwm1Regs.TBPRD = 800; // Period = 1600 TBCLK counts

EPwm1Regs.TBPHS.half.TBPHS = 0; // Set Phase register to zero

EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetrical mode

EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE; // Master module

EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW;

EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_CTR_ZERO; // Sync down-stream module

EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;

EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;

EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero

EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero

EPwm1Regs.AQCTLA.bit.CAU = AQ_SET; // set actions for EPWM1A

EPwm1Regs.AQCTLA.bit.CAD = AQ_CLEAR;

EPwm1Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE; // enable Dead-band module

EPwm1Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC; // Active Hi complementary

EPwm1Regs.DBFED = 50; // FED = 50 TBCLKs

EPwm1Regs.DBRED = 50; // RED = 50 TBCLKs // EPWM Module 2 config

EPwm2Regs.TBPRD = 800; // Period = 1600 TBCLK counts

EPwm2Regs.TBPHS.half.TBPHS = 0; // Set Phase register to zero

EPwm2Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetrical mode

EPwm2Regs.TBCTL.bit.PHSEN = TB_ENABLE; // Slave module

EPwm2Regs.TBCTL.bit.PRDLD = TB_SHADOW;

EPwm2Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN; // sync flow-through

EPwm2Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;

EPwm2Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;

EPwm2Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero

EPwm2Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero

EPwm2Regs.AQCTLA.bit.CAU = AQ_SET; // set actions for EPWM2A

EPwm2Regs.AQCTLA.bit.CAD = AQ_CLEAR;

EPwm2Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE; // enable Dead-band module

EPwm2Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC; // Active Hi complementary

EPwm2Regs.DBFED = 50; // FED = 50 TBCLKs

EPwm2Regs.DBRED = 50; // RED = 50 TBCLKs // EPWM Module 3 config

EPwm3Regs.TBPRD = 800; // Period = 1600 TBCLK counts

EPwm3Regs.TBPHS.half.TBPHS = 0; // Set Phase register to zero

EPwm3Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetrical mode

EPwm3Regs.TBCTL.bit.PHSEN = TB_ENABLE; // Slave module

EPwm3Regs.TBCTL.bit.PRDLD = TB_SHADOW;

EPwm3Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN; // sync flow-through

EPwm3Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;

EPwm3Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;

EPwm3Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero

EPwm3Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero

EPwm3Regs.AQCTLA.bit.CAU = AQ_SET; // set actions for EPWM3A

EPwm3Regs.AQCTLA.bit.CAD = AQ_CLEAR;

EPwm3Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE; // enable Dead-band module

EPwm3Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC; // Active Hi complementary

EPwm3Regs.DBFED = 50; // FED = 50 TBCLKs

EPwm3Regs.DBRED = 50; // RED = 50 TBCLKs // Run Time (Note: Example execution of one run-time instant) //=========================================================

EPwm1Regs.CMPA.half.CMPA = 500; // adjust duty for output EPWM1A

EPwm2Regs.CMPA.half.CMPA = 600; // adjust duty for output EPWM2A

EPwm3Regs.CMPA.half.CMPA = 700; // adjust duty for output EPWM3A

Applications to Power Topologies

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CTR=zero

CTR=CMPB

SyncOut

Phase reg

Ext SyncIn

(optional)

EPWM1A EPWM1B

SyncOut

Phase reg

CTR=CMPB

CTR=zero

EPWM2B

EPWM2A

Slave

Master

SyncIn

Φ=0°

Φ=120°

Applications to Power Topologies

3.7 Practical Applications Using Phase Control Between PWM Modules

So far, none of the examples have made use of the phase register (TBPHS). It has either been set to zero

or its value has been a don't care. However, by programming appropriate values into TBPHS, multiple

PWM modules can address another class of power topologies that rely on phase relationship between

legs (or stages) for correct operation. As described in the TB module section, a PWM module can be

configured to allow a SyncIn pulse to cause the TBPHS register to be loaded into the TBCTR register. To

illustrate this concept, Figure 57 shows a master and slave module with a phase relationship of 120°, i.e.,

the slave leads the master.

Figure 57. Configuring Two PWM Modules for Phase Control

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Figure 58 shows the associated timing waveforms for this configuration. Here, TBPRD = 600 for both

master and slave. For the slave, TBPHS = 200 (i.e., 200/600 X 360° = 120°). Whenever the master

generates a SyncIn pulse (CTR = PRD), the value of TBPHS = 200 is loaded into the slave TBCTR

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0000

FFFFh

TBPRD

TBCTR[0-15]

time

(SycnOut)

Master Module

Φ2

Phase = 120°

0000

FFFFh

TBPRD

TBCTR[0-15]

time

SyncIn

Slave Module

TBPHS

600 600

200

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Applications to Power Topologies

Figure 58. Timing Waveforms Associated With Phase Control Between 2 Modules

3.8 Controlling a 3-Phase Interleaved DC/DC Converter

A popular power topology that makes use of phase-offset between modules is shown in Figure 59. This

system uses three PWM modules, with module 1 configured as the master. To work, the phase

relationship between adjacent modules must be F = 120°. This is achieved by setting the slave TBPHS

registers 2 and 3 with values of 1/3 and 2/3 of the period value, respectively. For example, if the period

Both slave modules are synchronized to the master 1 module.

This concept can be extended to four or more phases, by setting the TBPHS values appropriately. The

following formula gives the TBPHS values for N phases:

TBPHS(N,M) = (TBPRD/N) x (—1)

Where:

N = number of phases

M = PWM module number For example, for the 3-phase case (N=3), TBPRD = 600, TBPHS(3,2) = (600/3) x (2-1) = 200 (i.e., Phase value for Slave module 2) TBPHS(3,3) = 400 (i.e., Phase value for Slave module 3)

Figure 60 shows the waveforms for the configuration in Figure 59.

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CTR=zero

CTR=CMPB

SyncOut

Phase reg

Ext SyncIn

(optional)

EPWM1A EPWM1B

SyncOut

Phase reg

CTR=CMPB

CTR=zero

EPWM2B

EPWM2A

Slave

Master

EPWM1A

SyncIn

EPWM1B

CTR=zero

CTR=CMPB

SyncOut

EPWM3B

Phase reg

Slave

SyncIn

EPWM3A

EPWM2B

EPWM2A EPWM3A

EPWM3B

OUT

Φ=0°

Φ=120°Φ=120°

Φ=240°

Applications to Power Topologies

Figure 59. Control of a 3-Phase Interleaved DC/DC Converter

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285

450

285

EPWM1A

EPWM1B

RED RED RED

FED FED FED

300

TBPHS

(=300)

300

EPWM2A

EPWM2B

TBPHS

(=300)

EPWM3A

EPWM3B

Φ2=120°

ZIZ

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Applications to Power Topologies

Figure 60. 3-Phase Interleaved DC/DC Converter Waveforms for Figure 59

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Applications to Power Topologies

Example 13. Code Snippet for Configuration in Figure 59

//===================================================================== // Config // Initialization Time //======================== // EPWM Module 1 config EPwm1Regs.TBPRD = 450; // Period = 900 TBCLK counts EPwm1Regs.TBPHS.half.TBPHS = 0; // Set Phase register to zero EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetrical mode EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE; // Master module EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW; EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_CTR_ZERO; // Sync down-stream module EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm1Regs.AQCTLA.bit.CAU = AQ_SET; // set actions for EPWM1A EPwm1Regs.AQCTLA.bit.CAD = AQ_CLEAR; EPwm1Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE; // enable Dead-band module EPwm1Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC; // Active Hi complementary EPwm1Regs.DBFED = 20; // FED = 20 TBCLKs EPwm1Regs.DBRED = 20; // RED = 20 TBCLKs // EPWM Module 2 config EPwm2Regs.TBPRD = 450; // Period = 900 TBCLK counts EPwm2Regs.TBPHS.half.TBPHS = 300; // Phase = 300/900 * 360 = 120 deg EPwm2Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetrical mode EPwm2Regs.TBCTL.bit.PHSEN = TB_ENABLE; // Slave module EPwm2Regs.TBCTL.bit.PHSDIR = TB_DOWN; // Count DOWN on sync (=120 deg) EPwm2Regs.TBCTL.bit.PRDLD = TB_SHADOW; EPwm2Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN; // sync flow-through EPwm2Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW; EPwm2Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW; EPwm2Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm2Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm2Regs.AQCTLA.bit.CAU = AQ_SET; // set actions for EPWM2A EPwm2Regs.AQCTLA.bit.CAD = AQ_CLEAR; EPwm2Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE; // enable Dead-band module EPwm2Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC; // Active Hi Complementary EPwm2Regs.DBFED = 20; // FED = 20 TBCLKs EPwm2Regs.DBRED = 20; // RED = 20 TBCLKs // EPWM Module 3 config EPwm3Regs.TBPRD = 450; // Period = 900 TBCLK counts EPwm3Regs.TBPHS.half.TBPHS = 300; // Phase = 300/900 * 360 = 120 deg EPwm3Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetrical mode EPwm3Regs.TBCTL.bit.PHSEN = TB_ENABLE; // Slave module EPwm2Regs.TBCTL.bit.PHSDIR = TB_UP; // Count UP on sync (=240 deg) EPwm3Regs.TBCTL.bit.PRDLD = TB_SHADOW; EPwm3Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN; // sync flow-through EPwm3Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW; EPwm3Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW; EPwm3Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm3Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm3Regs.AQCTLA.bit.CAU = AQ_SET; // set actions for EPWM3Ai EPwm3Regs.AQCTLA.bit.CAD = AQ_CLEAR; EPwm3Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE; // enable Dead-band module EPwm3Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC; // Active Hi complementary EPwm3Regs.DBFED = 20; // FED = 20 TBCLKs EPwm3Regs.DBRED = 20; // RED = 20 TBCLKs // Run Time (Note: Example execution of one run-time instant) //=========================================================== EPwm1Regs.CMPA.half.CMPA = 285; // adjust duty for output EPWM1A EPwm2Regs.CMPA.half.CMPA = 285; // adjust duty for output EPWM2A EPwm3Regs.CMPA.half.CMPA = 285; // adjust duty for output EPWM3A

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CTR=zero

CTR=CMPB

SyncOut

Phase reg

Ext SyncIn

(optional)

EPWM1A EPWM1B

SyncOut

Phase reg

CTR=CMPB

CTR=zero

EPWM2B

EPWM2A

Slave

Master

out

EPWM1A

SyncIn

DC_bus

EPWM1B

EPWM2A

EPWM2B

Φ=0°

Φ=Var°

Var = Variable

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3.9 Controlling Zero Voltage Switched Full Bridge (ZVSFB) Converter

The example given in Figure 61 assumes a static or constant phase relationship between legs (modules). In such a case, control is achieved by modulating the duty cycle. It is also possible to dynamically change the phase value on a cycle-by-cycle basis. This feature lends itself to controlling a class of power topologies known as phase-shifted full bridge, or zero voltage switched full bridge. Here the controlled parameter is not duty cycle (this is kept constant at approximately 50 percent); instead it is the phase relationship between legs. Such a system can be implemented by allocating the resources of two PWM modules to control a single power stage, which in turn requires control of four switching elements.

Figure 62 shows a master/slave module combination synchronized together to control a full H-bridge. In

this case, both master and slave modules are required to switch at the same PWM frequency. The phase is controlled by using the slave's phase register (TBPHS). The master's phase register is not used and therefore can be initialized to zero.

Applications to Power Topologies

Figure 61. Controlling a Full-H Bridge Stage (F

PWM2

= F

PWM1)

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Power phase

EPWM1A

EPWM1B

RED

300

Φ2=variable

TBPHS

=(1200−Φ2)

RED

EPWM2A

EPWM2B

Power phase

FED

200

600

1200

FED

ZVS transition

ZCA

Applications to Power Topologies

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Figure 62. ZVS Full-H Bridge Waveforms

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Example 14. Code Snippet for Configuration in Figure 61

//===================================================================== // Config //===================================================================== // Initialization Time //======================== // EPWM Module 1 config EPwm1Regs.TBPRD = 1200; // Period = 1201 TBCLK counts EPwm1Regs.CMPA = 600; // Set 50% fixed duty for EPWM1A EPwm1Regs.TBPHS.half.TBPHS = 0; // Set Phase register to zero EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP; // Asymmetrical mode EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE; // Master module EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW; EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_CTR_ZERO; // Sync down-stream module EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW; EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm1Regs.AQCTLA.bit.ZRO = AQ_SET; // set actions for EPWM1A EPwm1Regs.AQCTLA.bit.CAU = AQ_CLEAR; EPwm1Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE; // enable Dead-band module EPwm1Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC; // Active Hi complementary EPwm1Regs.DBFED = 50; // FED = 50 TBCLKs initially EPwm1Regs.DBRED = 70; // RED = 70 TBCLKs initially // EPWM Module 2 config EPwm2Regs.TBPRD = 1200; // Period = 1201 TBCLK counts EPwm2Regs.CMPA.half.CMPA = 600; // Set 50% fixed duty EPWM2A EPwm2Regs.TBPHS.half.TBPHS = 0; // Set Phase register to zero initially EPwm2Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP; // Asymmetrical mode EPwm2Regs.TBCTL.bit.PHSEN = TB_ENABLE; // Slave module EPwm2Regs.TBCTL.bit.PRDLD = TB_SHADOW; EPwm2Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN; // sync flow-through EPwm2Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW; EPwm2Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW; EPwm2Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm2Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero EPwm2Regs.AQCTLA.bit.ZRO = AQ_SET; // set actions for EPWM2A EPwm2Regs.AQCTLA.bit.CAU = AQ_CLEAR; EPwm2Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE; // enable Dead-band module EPwm2Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC; // Active Hi complementary EPwm2Regs.DBFED = 30; // FED = 30 TBCLKs initially EPwm2Regs.DBRED = 40; // RED = 40 TBCLKs initially // Run Time (Note: Example execution of one run-time instant) //============================================================ EPwm2Regs.TBPHS = 1200-300; // Set Phase reg to 300/1200 * 360 = 90 deg EPwm1Regs.DBFED = FED1_NewValue; // Update ZVS transition interval EPwm1Regs.DBRED = RED1_NewValue; // Update ZVS transition interval EPwm2Regs.DBFED = FED2_NewValue; // Update ZVS transition interval EPwm2Regs.DBRED = RED2_NewValue; // Update ZVS transition interval EPwm1Regs.CMPB = 200; // adjust point-in-time for ADCSOC trigger

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4 Registers

This chapter includes the register layouts and bit description for the submodules.

4.1 Time-Base Submodule Registers

Figure 63 through Figure 67 and Table 21 through Table 25 provide the time-base register definitions.

Figure 63. Time-Base Period Register (TBPRD)

15 0

TBPRD

R/W-0

LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

Table 21. Time-Base Period Register (TBPRD) Field Descriptions

Bits Name Value Description

15-0 TBPRD 0000- These bits determine the period of the time-base counter. This sets the PWM frequency.

FFFFh

Shadowing of this register is enabled and disabled by the TBCTL[PRDLD] bit. By default this register is shadowed.

• If TBCTL[PRDLD] = 0, then the shadow is enabled and any write or read will automatically go to the shadow register. In this case, the active register will be loaded from the shadow register when the time-base counter equals zero.

• If TBCTL[PRDLD] = 1, then the shadow is disabled and any write or read will go directly to the active register, that is the register actively controlling the hardware.

• The active and shadow registers share the same memory map address.

Figure 64. Time-Base Phase Register (TBPHS)

15 0

TBPHS

R/W-0

LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

Table 22. Time-Base Phase Register (TBPHS) Field Descriptions

Bits Name Value Description

15-0 TBPHS 0000-FFFF These bits set time-base counter phase of the selected ePWM relative to the time-base that is

supplying the synchronization input signal.

• If TBCTL[PHSEN] = 0, then the synchronization event is ignored and the time-base counter is

not loaded with the phase.

• If TBCTL[PHSEN] = 1, then the time-base counter (TBCTR) will be loaded with the phase

(TBPHS) when a synchronization event occurs. The synchronization event can be initiated by the input synchronization signal (EPWMxSYNCI) or by a software forced synchronization.

Figure 65. Time-Base Counter Register (TBCTR)

15 0

TBCTR

R/W-0

LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

Table 23. Time-Base Counter Register (TBCTR) Field Descriptions

Bits Name Value Description

15-0 TBCTR 0000- Reading these bits gives the current time-base counter value.

FFFF

Writing to these bits sets the current time-base counter value. The update happens as soon as the write occurs; the write is NOT synchronized to the time-base clock (TBCLK) and the register is not shadowed.

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Figure 66. Time-Base Control Register (TBCTL)

15 14 13 12 10 9 8

FREE, SOFT PHSDIR CLKDIV HSPCLKDIV

R/W-0 R/W-0 R/W-0 R/W-0,0,1

7 6 5 4 3 2 1 0

HSPCLKDIV SWFSYNC SYNCOSEL PRDLD PHSEN CTRMODE

R/W-0,0,1 R/W-0 R/W-0 R/W-0 R/W-0 R/W-11

LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

Table 24. Time-Base Control Register (TBCTL) Field Descriptions

Bit Field Value Description

15:14 FREE, SOFT Emulation Mode Bits. These bits select the behavior of the ePWM time-base counter during

emulation events: 00 Stop after the next time-base counter increment or decrement 01 Stop when counter completes a whole cycle:

• Up-count mode: stop when the time-base counter = period (TBCTR = TBPRD)

• Down-count mode: stop when the time-base counter = 0x0000 (TBCTR = 0x0000)

• Up-down-count mode: stop when the time-base counter = 0x0000 (TBCTR = 0x0000)

1X Free run

13 PHSDIR Phase Direction Bit.

This bit is only used when the time-base counter is configured in the up-down-count mode. The

PHSDIR bit indicates the direction the time-base counter (TBCTR) will count after a synchronization

event occurs and a new phase value is loaded from the phase (TBPHS) register. This is

irrespective of the direction of the counter before the synchronization event..

In the up-count and down-count modes this bit is ignored.

0 Count down after the synchronization event. 1 Count up after the synchronization event.

12:10 CLKDIV Time-base Clock Prescale Bits

These bits determine part of the time-base clock prescale value.

TBCLK = SYSCLKOUT / (HSPCLKDIV × CLKDIV)

000 /1 (default on reset) 001 /2 010 /4 011 /8 100 /16 101 /32 110 /64 111 /128

9:7 HSPCLKDIV High Speed Time-base Clock Prescale Bits

These bits determine part of the time-base clock prescale value.

TBCLK = SYSCLKOUT / (HSPCLKDIV × CLKDIV)

This divisor emulates the HSPCLK in the TMS320x281x system as used on the Event Manager

(EV) peripheral.

000 /1 001 /2 (default on reset) 010 /4 011 /6 100 /8 101 /10 110 /12 111 /14

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Table 24. Time-Base Control Register (TBCTL) Field Descriptions (continued)

Bit Field Value Description

6 SWFSYNC Software Forced Synchronization Pulse

0 Writing a 0 has no effect and reads always return a 0. 1 Writing a 1 forces a one-time synchronization pulse to be generated.

This event is ORed with the EPWMxSYNCI input of the ePWM module.

SWFSYNC is valid (operates) only when EPWMxSYNCI is selected by SYNCOSEL = 00.

5:4 SYNCOSEL Synchronization Output Select. These bits select the source of the EPWMxSYNCO signal.

00 EPWMxSYNC: 01 CTR = zero: Time-base counter equal to zero (TBCTR = 0x0000) 10 CTR = CMPB : Time-base counter equal to counter-compare B (TBCTR = CMPB) 11 Disable EPWMxSYNCO signal

3 PRDLD Active Period Register Load From Shadow Register Select

0 The period register (TBPRD) is loaded from its shadow register when the time-base counter,

TBCTR, is equal to zero.

A write or read to the TBPRD register accesses the shadow register.

1 Load the TBPRD register immediately without using a shadow register.

A write or read to the TBPRD register directly accesses the active register.

2 PHSEN Counter Register Load From Phase Register Enable

0 Do not load the time-base counter (TBCTR) from the time-base phase register (TBPHS) 1 Load the time-base counter with the phase register when an EPWMxSYNCI input signal occurs or

when a software synchronization is forced by the SWFSYNC bit

1:0 CTRMODE Counter Mode

The time-base counter mode is normally configured once and not changed during normal operation.

If you change the mode of the counter, the change will take effect at the next TBCLK edge and the

current counter value shall increment or decrement from the value before the mode change.

These bits set the time-base counter mode of operation as follows: 00 Up-count mode 01 Down-count mode 10 Up-down-count mode 11 Stop-freeze counter operation (default on reset)

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Figure 67. Time-Base Status Register (TBSTS)

15 8

Reserved

R-0

7 3 2 1 0

Reserved CTRMAX SYNCI CTRDIR

R-0 R/W1C-0 R/W1C-0 R-1

LEGEND: R/W = Read/Write; R = Read only; R/W1C = Read/Write 1 to clear; -n = value after reset

Table 25. Time-Base Status Register (TBSTS) Field Descriptions

Bit Field Value Description

15:3 Reserved Reserved

2 CTRMAX Time-Base Counter Max Latched Status Bit

0 Reading a 0 indicates the time-base counter never reached its maximum value. Writing a 0 will

have no effect.

1 Reading a 1 on this bit indicates that the time-base counter reached the max value 0xFFFF. Writing

a 1 to this bit will clear the latched event.

1 SYNCI Input Synchronization Latched Status Bit

0 Writing a 0 will have no effect. Reading a 0 indicates no external synchronization event has

occurred.

1 Reading a 1 on this bit indicates that an external synchronization event has occurred

(EPWMxSYNCI). Writing a 1 to this bit will clear the latched event.

0 CTRDIR Time-Base Counter Direction Status Bit. At reset, the counter is frozen; therefore, this bit has no

meaning. To make this bit meaningful, you must first set the appropriate mode via

TBCTL[CTRMODE].

0 Time-Base Counter is currently counting down. 1 Time-Base Counter is currently counting up.

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4.2 Counter-Compare Submodule Registers

Figure 68 through Figure 70 and Table 26 through Table 28 illustrate the counter-compare submodule

control and status registers.

Figure 68. Counter-Compare A Register (CMPA)

15 0

CMPA R/W-0

LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

Table 26. Counter-Compare A Register (CMPA) Field Descriptions

Bits Name Description

15-0 CMPA The value in the active CMPA register is continuously compared to the time-base counter (TBCTR). When

the values are equal, the counter-compare module generates a "time-base counter equal to counter compare A" event. This event is sent to the action-qualifier where it is qualified and converted it into one or more actions. These actions can be applied to either the EPWMxA or the EPWMxB output depending on the configuration of the AQCTLA and AQCTLB registers. The actions that can be defined in the AQCTLA and AQCTLB registers include:

• Do nothing; the event is ignored.

• Clear: Pull the EPWMxA and/or EPWMxB signal low

• Set: Pull the EPWMxA and/or EPWMxB signal high

• Toggle the EPWMxA and/or EPWMxB signal

Shadowing of this register is enabled and disabled by the CMPCTL[SHDWAMODE] bit. By default this register is shadowed.

• If CMPCTL[SHDWAMODE] = 0, then the shadow is enabled and any write or read will automatically go to the shadow register. In this case, the CMPCTL[LOADAMODE] bit field determines which event will load the active register from the shadow register.

• Before a write, the CMPCTL[SHDWAFULL] bit can be read to determine if the shadow register is currently full.

• If CMPCTL[SHDWAMODE] = 1, then the shadow register is disabled and any write or read will go directly to the active register, that is the register actively controlling the hardware.

• In either mode, the active and shadow registers share the same memory map address.

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Figure 69. Counter-Compare B Register (CMPB)

15 0

CMPB R/W-0

LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

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Table 27. Counter-Compare B Register (CMPB) Field Descriptions

Bits Name Description

15-0 CMPB The value in the active CMPB register is continuously compared to the time-base counter (TBCTR). When

the values are equal, the counter-compare module generates a "time-base counter equal to counter compare B" event. This event is sent to the action-qualifier where it is qualified and converted it into one or more actions. These actions can be applied to either the EPWMxA or the EPWMxB output depending on the configuration of the AQCTLA and AQCTLB registers. The actions that can be defined in the AQCTLA and AQCTLB registers include:

• Do nothing. event is ignored.

• Clear: Pull the EPWMxA and/or EPWMxB signal low

• Set: Pull the EPWMxA and/or EPWMxB signal high

• Toggle the EPWMxA and/or EPWMxB signal

Shadowing of this register is enabled and disabled by the CMPCTL[SHDWBMODE] bit. By default this register is shadowed.

• If CMPCTL[SHDWBMODE] = 0, then the shadow is enabled and any write or read will automatically go to the shadow register. In this case, the CMPCTL[LOADBMODE] bit field determines which event will load the active register from the shadow register:

• Before a write, the CMPCTL[SHDWBFULL] bit can be read to determine if the shadow register is currently full.

• If CMPCTL[SHDWBMODE] = 1, then the shadow register is disabled and any write or read will go directly to the active register, that is the register actively controlling the hardware.

• In either mode, the active and shadow registers share the same memory map address.

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Figure 70. Counter-Compare Control Register (CMPCTL)

15 10 9 8

Reserved SHDWBFULL SHDWAFULL

R-0 R-0 R-0

7 6 5 4 3 2 1 0

Reserved SHDWBMODE Reserved SHDWAMODE LOADBMODE LOADAMODE

R-0 R/W-0 R-0 R/W-0 R/W-0 R/W-0

LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

Table 28. Counter-Compare Control Register (CMPCTL) Field Descriptions

Bits Name Value Description

15-10 Reserved Reserved

9 SHDWBFULL Counter-compare B (CMPB) Shadow Register Full Status Flag

This bit self clears once a load-strobe occurs. 0 CMPB shadow FIFO not full yet 1 Indicates the CMPB shadow FIFO is full; a CPU write will overwrite current shadow value.

8 SHDWAFULL Counter-compare A (CMPA) Shadow Register Full Status Flag

The flag bit is set when a 32-bit write to CMPA:CMPAHR register or a 16-bit write to CMPA

This bit self clears once a load-strobe occurs. 0 CMPA shadow FIFO not full yet 1 Indicates the CMPA shadow FIFO is full, a CPU write will overwrite the current shadow

value.

7 Reserved Reserved 6 SHDWBMODE Counter-compare B (CMPB) Register Operating Mode

0 Shadow mode. Operates as a double buffer. All writes via the CPU access the shadow

access the active register for immediate compare action.

5 Reserved Reserved 4 SHDWAMODE Counter-compare A (CMPA) Register Operating Mode

0 Shadow mode. Operates as a double buffer. All writes via the CPU access the shadow

access the active register for immediate compare action

3-2 LOADBMODE Active Counter-Compare B (CMPB) Load From Shadow Select Mode

This bit has no effect in immediate mode (CMPCTL[SHDWBMODE] = 1).

00 Load on CTR = Zero: Time-base counter equal to zero (TBCTR = 0x0000) 01 Load on CTR = PRD: Time-base counter equal to period (TBCTR = TBPRD) 10 Load on either CTR = Zero or CTR = PRD 11 Freeze (no loads possible)

1-0 LOADAMODE Active Counter-Compare A (CMPA) Load From Shadow Select Mode.

This bit has no effect in immediate mode (CMPCTL[SHDWAMODE] = 1).

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Figure 71. Compare A High Resolution Register (CMPAHR)

15 8

CMPAHR

R/W-0

7 0

Reserved

R-0

LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

Table 29. Compare A High Resolution Register (CMPAHR) Field Descriptions

Bit Field Value Description

15-8 CMPAHR 00-FFh These 8-bits contain the high-resolution portion (least significant 8-bits) of the counter-compare A

value. CMPA:CMPAHR can be accessed in a single 32-bit read/write. Shadowing is enabled and disabled by the CMPCTL[SHDWAMODE] bit as described for the CMPA

7-0 Reserved Reserved for TI Test

4.3 Action-Qualifier Submodule Registers

Figure 72 through Figure 75 and Table 30 through Table 33 provide the action-qualifier submodule

Registers

Figure 72. Action-Qualifier Output A Control Register (AQCTLA)

15 12 11 10 9 8

Reserved CBD CBU

R-0 R/W-0 R/W-0

7 6 5 4 3 2 1 0

CAD CAU PRD ZRO

R/W-0 R/W-0 R/W-0 R/W-0

LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

Table 30. Action-Qualifier Output A Control Register (AQCTLA) Field Descriptions

Bits Name Value Description

15-12 Reserved Reserved 11-10 CBD Action when the time-base counter equals the active CMPB register and the counter is

9-8 CBU Action when the counter equals the active CMPB register and the counter is incrementing.

7-6 CAD Action when the counter equals the active CMPA register and the counter is decrementing.

decrementing. 00 Do nothing (action disabled) 01 Clear: force EPWMxA output low. 10 Set: force EPWMxA output high. 11 Toggle EPWMxA output: low output signal will be forced high, and a high signal will be forced low.

00 Do nothing (action disabled) 01 Clear: force EPWMxA output low. 10 Set: force EPWMxA output high. 11 Toggle EPWMxA output: low output signal will be forced high, and a high signal will be forced low.

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Table 30. Action-Qualifier Output A Control Register (AQCTLA) Field Descriptions (continued)

Bits Name Value Description

5-4 CAU Action when the counter equals the active CMPA register and the counter is incrementing.

3-2 PRD Action when the counter equals the period.

Note: By definition, in count up-down mode when the counter equals period the direction is defined

as 0 or counting down. 00 Do nothing (action disabled) 01 Clear: force EPWMxA output low. 10 Set: force EPWMxA output high. 11 Toggle EPWMxA output: low output signal will be forced high, and a high signal will be forced low.

1-0 ZRO Action when counter equals zero.

Note: By definition, in count up-down mode when the counter equals 0 the direction is defined as 1

or counting up. 00 Do nothing (action disabled) 01 Clear: force EPWMxA output low. 10 Set: force EPWMxA output high. 11 Toggle EPWMxA output: low output signal will be forced high, and a high signal will be forced low.

Figure 73. Action-Qualifier Output B Control Register (AQCTLB)

15 12 11 10 9 8

Reserved CBD CBU

R-0 R/W-0 R/W-0

7 6 5 4 3 2 1 0

CAD CAU PRD ZRO

R/W-0 R/W-0 R/W-0 R/W-0

LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

Table 31. Action-Qualifier Output B Control Register (AQCTLB) Field Descriptions

Bits Name Value Description

15-12 Reserved 11-10 CBD Action when the counter equals the active CMPB register and the counter is decrementing.

00 Do nothing (action disabled) 01 Clear: force EPWMxB output low. 10 Set: force EPWMxB output high. 11 Toggle EPWMxB output: low output signal will be forced high, and a high signal will be forced low.

9-8 CBU Action when the counter equals the active CMPB register and the counter is incrementing.

7-6 CAD Action when the counter equals the active CMPA register and the counter is decrementing.

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Table 31. Action-Qualifier Output B Control Register (AQCTLB) Field Descriptions (continued)

Bits Name Value Description

5-4 CAU Action when the counter equals the active CMPA register and the counter is incrementing.

3-2 PRD Action when the counter equals the period.

Note: By definition, in count up-down mode when the counter equals period the direction is defined

as 0 or counting down. 00 Do nothing (action disabled) 01 Clear: force EPWMxB output low. 10 Set: force EPWMxB output high. 11 Toggle EPWMxB output: low output signal will be forced high, and a high signal will be forced low.

1-0 ZRO Action when counter equals zero.

Note: By definition, in count up-down mode when the counter equals 0 the direction is defined as 1

or counting up. 00 Do nothing (action disabled) 01 Clear: force EPWMxB output low. 10 Set: force EPWMxB output high. 11 Toggle EPWMxB output: low output signal will be forced high, and a high signal will be forced low.

Figure 74. Action-Qualifier Software Force Register (AQSFRC)

15 8

Reserved

R-0

7 6 5 4 3 2 1 0

RLDCSF OTSFB ACTSFB OTSFA ACTSFA

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

Table 32. Action-Qualifier Software Force Register (AQSFRC) Field Descriptions

Bit Field Value Description

15:8 Reserved

7:6 RLDCSF AQCSFRC Active Register Reload From Shadow Options

00 Load on event counter equals zero 01 Load on event counter equals period 10 Load on event counter equals zero or counter equals period 11 Load immediately (the active register is directly accessed by the CPU and is not loaded from the

shadow register).

5 OTSFB One-Time Software Forced Event on Output B

0 Writing a 0 (zero) has no effect. Always reads back a 0

This bit is auto cleared once a write to this register is complete, i.e., a forced event is initiated.) This is a one-shot forced event. It can be overridden by another subsequent event on output B.

1 Initiates a single s/w forced event

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Table 32. Action-Qualifier Software Force Register (AQSFRC) Field Descriptions (continued)

Bit Field Value Description

4:3 ACTSFB Action when One-Time Software Force B Is invoked

00 Does nothing (action disabled) 01 Clear (low) 10 Set (high) 11 Toggle (Low -> High, High -> Low)

Note: This action is not qualified by counter direction (CNT_dir)

2 OTSFA One-Time Software Forced Event on Output A

0 Writing a 0 (zero) has no effect. Always reads back a 0.

This bit is auto cleared once a write to this register is complete ( i.e., a forced event is initiated).

1 Initiates a single software forced event

1:0 ACTSFA Action When One-Time Software Force A Is Invoked

00 Does nothing (action disabled) 01 Clear (low) 10 Set (high) 11 Toggle (Low → High, High → Low)

Note: This action is not qualified by counter direction (CNT_dir)

Figure 75. Action-Qualifier Continuous Software Force Register (AQCSFRC)

15 8

Reserved

R-0

7 4 3 2 1 0

Reserved CSFB CSFA

R-0 R/W-0 R/W-0

LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

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Table 33. Action-qualifier Continuous Software Force Register (AQCSFRC) Field Descriptions

Bits Name Value Description

15-4 Reserved Reserved

3-2 CSFB Continuous Software Force on Output B

In immediate mode, a continuous force takes effect on the next TBCLK edge. In shadow mode, a continuous force takes effect on the next TBCLK edge after a shadow load into

the active register. To configure shadow mode, use AQSFRC[RLDCSF]. 00 Forcing disabled, i.e., has no effect 01 Forces a continuous low on output B 10 Forces a continuous high on output B 11 Software forcing is disabled and has no effect

1-0 CSFA Continuous Software Force on Output A

In immediate mode, a continuous force takes effect on the next TBCLK edge.

In shadow mode, a continuous force takes effect on the next TBCLK edge after a shadow load into

the active register. 00 Forcing disabled, i.e., has no effect 01 Forces a continuous low on output A 10 Forces a continuous high on output A 11 Software forcing is disabled and has no effect

100

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Specifications and Main Features

Frequently Asked Questions

User Manual

SPRUG04A–October 2008–Revised July 2009 Table of Contents

Preface

1 Introduction

1.1 Submodule Overview

1.2 Register Mapping

2 ePWM Submodules

2.1 Overview

2.2 Time-Base (TB) Submodule

2.2.1 Purpose of the Time-Base Submodule

2.2.2 Controlling and Monitoring the Time-base Submodule

2.2.3 Calculating PWM Period and Frequency

2.2.3.1 Time-Base Period Shadow Register

2.2.3.2 Time-Base Clock Synchronization

2.2.3.3 Time-Base Counter Synchronization

2.2.4 Phase Locking the Time-Base Clocks of Multiple ePWM Modules

2.2.5 Time-base Counter Modes and Timing Waveforms

2.3 Counter-Compare (CC) Submodule

2.3.1 Purpose of the Counter-Compare Submodule

2.3.2 Controlling and Monitoring the Counter-Compare Submodule

2.3.3 Operational Highlights for the Counter-Compare Submodule

2.3.4 Count Mode Timing Waveforms

2.4 Action-Qualifier (AQ) Submodule

2.4.1 Purpose of the Action-Qualifier Submodule

2.4.2 Action-Qualifier Submodule Control and Status Register Definitions

2.4.3 Action-Qualifier Event Priority

2.4.4 Waveforms for Common Configurations

2.5 Dead-Band Generator (DB) Submodule

2.5.1 Purpose of the Dead-Band Submodule

2.5.2 Controlling and Monitoring the Dead-Band Submodule

2.5.3 Operational Highlights for the Dead-Band Submodule

2.6 PWM-Chopper (PC) Submodule

2.6.1 Purpose of the PWM-Chopper Submodule

2.6.2 Controlling the PWM-Chopper Submodule

2.6.3 Operational Highlights for the PWM-Chopper Submodule

2.6.4 Waveforms

2.6.4.1 One-Shot Pulse

2.6.4.2 Duty Cycle Control

2.7 Trip-Zone (TZ) Submodule

2.7.1 Purpose of the Trip-Zone Submodule

2.7.2 Controlling and Monitoring the Trip-Zone Submodule

2.7.3 Operational Highlights for the Trip-Zone Submodule

2.7.4 Generating Trip Event Interrupts

2.8 Event-Trigger (ET) Submodule

2.8.1 Operational Overview of the Event-Trigger Submodule

3 Applications to Power Topologies

3.1 Overview of Multiple Modules

3.2 Key Configuration Capabilities

3.3 Controlling Multiple Buck Converters With Independent Frequencies

3.4 Controlling Multiple Buck Converters With Same Frequencies

3.5 Controlling Multiple Half H-Bridge (HHB) Converters

3.6 Controlling Dual 3-Phase Inverters for Motors (ACI and PMSM)

3.7 Practical Applications Using Phase Control Between PWM Modules

3.8 Controlling a 3-Phase Interleaved DC/DC Converter

3.9 Controlling Zero Voltage Switched Full Bridge (ZVSFB) Converter

4 Registers

4.1 Time-Base Submodule Registers

4.2 Counter-Compare Submodule Registers

4.3 Action-Qualifier Submodule Registers