Digilent 410-262P User Manual

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chipKIT™ Motor Shield

Reference Manual

Revision: April 16, 2013 Note: This document applies to REV D of the board.

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Overview

The chipKIT™ Motor Shield is an expansion board for use with the chipKIT Uno32 and chipKIT uC32. It provides additional circuitry and connectors for the Uno32 and uC32 to drive various motors types.

The chipKIT Motor Shield is designed to drive DC motors, servo motors, and stepper motors. It also provides additional I/O via an I2C I/O extender.

Features include:

 2 DC motor driver channels,

accessible with either a JST 6-pin connector or a terminal block

 2 DC motor encoder input signals for

each DC motor channel

 4 servo motor channels  I2C General purpose I/O expander

with 4 LEDs 2 push buttons and 2 user settable jumpers

 1 4-wire unipolar stepper motor

channel

 Standard chipKIT Shield connectors

Functional Description

The chipKIT Motor Shield is designed to be used with the chipKIT Uno32 or chipKIT uC32 board. When used with these boards, the microcontroller and shield provide the necessary supporting hardware and connectors to control most types of small motors. The rest of this document will only reference the Uno32; however, the shield can also be used with the chipKIT uC32.

The chipKIT Motor Shield has the following connectors:

J1: Power Supply for the DC motor driver

This connector provides power to the DVR8833RTY motor driver for the DC motors. Motor supply voltage range is 2.7-10.8 V.

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chipKIT Motor Shield Reference Manual

J3 & J6: DC motor 6-pin JST connector

These connections provide power and feedback signals for DC motors. The pin-outs are compatible with the Digilent DC gear-motors.

J5 & J7: DC motor terminal block connector

These connections provide the power supply pin-out for most two wire DC motors.

J2: DC motor driver disable

Shorting these two pins (or driving the NS signal pin low) will put the DC motor driver into sleep mode. This disables the motor driver and therefore reduces power consumption. This option is useful for low power applications.

J4: DC motor driver fault indicator

The NF signal will be driven low when there is a fault detected within the DC motor driver. Possible reasons for fault include overcurrent, overheat, and low voltage.

J8 & J9: DC motor feedback signal headers

Headers for connecting DC motor feedback signals.

J10: Power Supply for Stepper motor

This connector provides power for driving the stepper motor.

J12 & J13: Stepper motor terminal block connectors

These connections are used for driving a stepper motor.

J14: Power Supply for servo motors

This connector provides external power for driving the servo motors. If using this header remove JP6 to ensure that servo power supply is not shorted to the 5 Volt Uno32 power supply.

J11 & J15: Digital Signal Pass-Through Connectors

This connector passes the digital I/O pins on the Uno32 through to the chipKIT Motor Shield.

J21: I2C #1 Daisy Chain Connector

This is a 2x4 pin header connector that provides access to the I2C signals SDA and SCL as well as power from the 3.3V power bus and ground. This can be used to extend the I2C bus off of the board and to power external I2C devices. Digilent has cables and a selection of I2C peripheral modules that can be accessed using this connector.

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chipKIT Motor Shield Reference Manual

Uno32

Pin #

PIC32

Pin #

Signal

Notes

Enable1: OC1/RD0

4 59

Direction1: RF1

3/5

46/49

Enable2: OC1/RD0 or OC2/RD1

Select with JP1

4/34

59/53

Direction2: RF1 or PMRD/CN14/RD5

Select with JP2

DIR1

EN1

Result

0 0 Stop

1/PWM

Forward

1 0 Stop

1/PWM

Reverse

DIR2

EN2

Result

0 0 Stop

1/PWM

Forward

1 0 Stop

1/PWM

Reverse

J19: Analog Signal Pass-Through Connector

This connector passes the analog input pins on the Uno32 through the chipKIT Motor Shield.

J22: Power Pass-Through Connector

This connector passes the power connector from the Uno32 through the chipKIT Motor Shield, and powers the chipKIT Motor Shield from the Uno32.

DC Motor Controller

The Motor Shield provides a means to control 2 independent DC motors via a DRV883 dual H-bridge motor driver. The motor driver must be powered via J1 to operate, voltages between 2.7 and 10.8 volts are acceptable. Each channel is controlled by an “enable” and “direction” signal.

Channel 2 can be set up for identical or independent operation from channel 1 using JP1 and JP2. PWM levels on enable pins will regulate the speed of the motors. Logic levels on direction pins will

determine the motors rotation direction of the attached DC motors. The chipKIT Uno32 uses a demultiplexer and pull-down resistors on the inputs to the DRV8833 H-Bridge pins to ensure that the H-Bridge only works in fast decay mode. Table 1 lists the motor responses that result from various input combinations.

The DRV8833 chip provides overcurrent protection on the motor drive circuits. Each internal drive FET is independently monitored for an overcurrent condition and will be shut down internally to protect the chip. When an overcurrent condition is sensed the chip will shut down the FET with the fault and then set the NFAULT pin low signaling a fault condition on the chip. The remaining FETs will continue to operate as normal. When the fault condition is over, the chip will self-reset and return the NFAULT logic level to logic high. (See Table 2 for connector descriptions.)

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Table 1: Motor Control

chipKIT Motor Shield Reference Manual

Uno32

Pin #

PIC32

Pin #

Signal

Notes

A: PMD0/RE0

B: PMD1/RE1

C: PMD2/RE2

D: PMD3/RE3

Uno32

Pin #

PIC32

Pin #

Signal

Notes

Servo1: PMD4/RE4

J16

Servo2: PMD5/RE5

J17

Servo3: PMD6/RE6

J18

Servo4: PMD7/RE7

J20

There are two Schmitt trigger buffered inputs on connectors J3, J6, J8 and J9 that bring motor speed feedback signals to the controlling system board. The Digilent motor and gearbox have hall-effect sensors arranged in a quadrature encoder format. These buffers have 5V tolerant inputs, when operated at 3.3V.

The quadrature encoder signals are a pair of square waves whose frequency is proportional to motor rotation speed and with the pulses 90 out of phase. You can determine the motor speed with the frequency and motor rotation direction by the phase relationship between the two signals.

Stepper Motor Controller

The stepper motor controller has 4 output signals. It is composed of 4 open-drain transistor amplifiers.

The stepper motor driver can be powered by either VIN, or an external power source connected to J10. If connecting an external power source, JP5 should be removed to prevent shorting the stepper motor voltages to the input voltage of the chipKIT board.

Servo Motors

The Motor Shield has 4 servo motor connections. They can be powered from VCC5V0 or an external power source connected to J14. If connecting an external power source, JP6 should be removed. The voltage of the power source can be measured on analog pin A11 via a resistor divider network (see the schematic for more details).

I2C Bus and Connectors

The Inter-Integrated Circuit (I2C) Interface provides a medium speed (100K or 400K bps) synchronous serial communications bus. The I2C interface provides master and slave operation using either 7 bit or 10 bit device addressing. Each device is given a unique address, and the protocol provides the ability to address packets to a specific device or to broadcast packets to all devices on the bus. Refer to the Microchip PIC32MX3XX data sheet and the PIC32 Family Reference Manual for detailed information on configuring and using the I2C interface.

The PIC32MX320 microcontroller on the Uno32 provides for two independent I2C interfaces. The Motor Shield is designed to provide access to one of these interfaces, I2C #1 (SCL1, SDA1). I2C #1 is accessed through the standard chipKIT Wire library. Connector J21 provides access to I2C port #1.

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chipKIT Motor Shield Reference Manual

Connector J21 can be used to extend the I2C bus off of the board to connect to external I2C devices.

This is a standard 2x4 pin header connector with 0.100” spaced pins. It provides access to the I

C signals, SCL1 and SDA1, plus VCC3V3 and ground. The VCC3V3 can be used to power external I2C devices.

The I2C bus uses open collector drivers to allow multiple devices to drive the bus signals. This means that pull-up resistors must be provided to supply the logic high state for the signals. The Motor Shield provides 2.2Kohm pull-up resistors on I2C #1.

Generally, only one set of pull-ups are used on the bus. Jumpers JP7 and JP8 can be used to disable the on-board pull-ups on I2C #1 if a different value is needed or some other device on the bus is providing the pull-ups or if I2C #1 isn’t being used and the pull-ups are interfering with the use of the pins. The on-board pull-ups are enabled by install shorting blocks on JP7 and JP8. Removing the shorting blocks disables the pull-ups.

Digilent has several small I/O modules available that can be connected using the I2C connector. These include a 3-axis accelerometer, 4-channel, 12-bit A/D converter, serial character LCD panel, 3axis gyroscope, and a real-time clock/calendar. The on-board I/O expander is also controlled via I2C #1.

I/O Expander

The Motor Shield contains an I/O expander module that gives access to 4 LEDs, 2 pushbuttons, and 2 jumper-switches. The I/O expander is controlled via I2C #1. The outputs can be easily controlled using

the Motor Shield MPIDE library.

CHIPKIT and the CHIPKIT Logo are trademarks or registered trademarks of Microchip Technology Incorporated in the U.S. and other countries, and are used under license.

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chipKIT Motor Shield Reference Manual

Uno32

Pin #

PIC32

Pin #

Signal

Notes

J1-01

VM (motor driver power supply)

2.7-10.8 V

J1-02

GND

Uno32

Pin #

PIC32

Pin #

Signal

Notes

J2-01

Motor Driver NSLEEP

Pull low to sleep

J2-02

GND

Uno32

Pin #

PIC32

Pin #

Signal

Notes

J4-01

Motor Driver NFAULT

Goes low on error

J4-02

GND

Uno32

Pin #

PIC32

Pin #

Signal

Notes

J3-01

SB1-IN J3-02

SA1-IN J3-03

GND J3-04

VCC3V3

J3-05

M1+ J3-06

M1-

Uno32

Pin #

PIC32

Pin #

Signal

Notes

J6-01

SB2-IN J6-02

SA2-IN J6-03

GND J6-04

VCC3V3

J6-05

M2+

J6-06

M2-

Appendix: chipKIT Motor Shield Pin-out Tables J1 Pins

J2 Pins

J4 Pins

J3 Pins

J6 Pins

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chipKIT Motor Shield Reference Manual

Uno32

Pin #

PIC32

Pin #

Signal

Notes

J5-01

M1+ J5-02

M1+

Uno32

Pin #

PIC32

Pin #

Signal

Notes

J7-01

M2+ J7-02

M2-

Uno32

Pin #

PIC32

Pin #

Signal

Notes

J8-01

SA1-IN/ Jumper#3

See JP3

20/A6

J8-02

SB1-IN/A6

J8-03

GND J8-04

VCC3V3

Uno32

Pin #

PIC32

Pin #

Signal

Notes

J9-01

SA2-IN/IC2/INT2/RD9

J9-02

SB1-IN/CN16/RD7

J9-03

GND J9-04

VCC3V3

Uno32

Pin #

PIC32

Pin #

Signal

Notes

JP3-01

IC1/INT1/RD8

JP3-02

SB1-IN

Select with jumper

JP3-03

IC4/PMCS1/PMAI4/INT4/R11

J5 Pins

J7 Pins

J8 Pins

J9 Pins

JP3 Pins

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chipKIT Motor Shield Reference Manual

Uno32

Pin #

PIC32

Pin #

Signal

Notes

J10-01

External V+/VIN

Select with JP5

J10-02

External V-/GND

J12-01

StepperA/PMD0/RE0

J12-02

StepperB/PMD1/RE1

J13-01

StepperC/PMD2/RE2

J13-02

StepperD/PMD3/RE3

Uno32

Pin #

PIC32

Pin #

Signal

Notes

J14-01

External Vs+/VCC5V0

Select with JP6

J14-02

GND 30

J16-01

PMD4/RE4

J16-02

External Vs+/VCC5V0

J16-03

GND 31

J17-01

PMD5/RE5

J17-02

External Vs+/VCC5V0

J17-03

GND 32

J18-01

PMD6/RE6

J18-02

External Vs+/VCC5V0

J18-03

GND 33

J19-01

PMD7/RE7

J19-02

External Vs+/VCC5V0

J19-03

GND

Uno32

Pin #

PIC32

Pin #

Signal

Notes

J21-01

SCL1/RG2

J21-02

SCL1/RG2

J21-03

SDA1/RG3

J21-04

SDA1/RG3

J21-05

GND J21-06

GND

J21-07

VCC3V3

J21-08

VCC3V3

J10 & J12 & J13 Pins (Stepper Motor Connections)

J14 & J16 & J17 & J18 & J20 Pins (Servo Motor Connections)

J21 Pins (I2C)

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Digilent 410-262P User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual