Philips LPC2131, LPC2132, LPC2134, LPC2136, LPC2138 User Guide

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UM10120

Volume 1: LPC213x User Manual

Rev. 01 — 24 June 2005 User manual

Document information

Info	Content
Keywords	LPC2131, LPC2132, LPC2134, LPC2136, LPC2138, LPC2000, LPC213x,
	ARM, ARM7, embedded, 32-bit, microcontroller

Abstract	An initial LPC213x User Manual revision

Philips Semiconductors			UM10120
	Volume 1		LPC2131/2/4/6/8 UM
Revision history

Rev	Date	Description

01	20050624	Initial version

Contact information

For additional information, please visit: http://www.semiconductors.philips.com

For sales office addresses, please send an email to: sales.addresses@www.semiconductors.philips.com

User manual

Rev. 01 — 24 June 2005

UM10120

Chapter 1: General information

Rev. 01 — 24 June 2005 User manual

1.1 Introduction

The LPC2131/32/34/36/38 microcontrollers are based on a 16/32 bit ARM7TDMI-S™ CPU with real-time emulation and embedded trace support, that combines the microcontroller with 32 kB, 64 kB, 128 kB, 256 kB and 512 kB of embedded high speed Flash memory. A 128-bit wide memory interface and a unique accelerator architecture enable 32-bit code execution at maximum clock rate. For critical code size applications, the alternative 16-bit Thumb® Mode reduces code by more than 30 % with minimal performance penalty.

Due to their tiny size and low power consumption, these microcontrollers are ideal for applications where miniaturization is a key requirement, such as access control and point-of-sale. With a wide range of serial communications interfaces and on-chip SRAM options of 8/16/32 kB, they are very well suited for communication gateways and protocol converters, soft modems, voice recognition and low end imaging, providing both large buffer size and high processing power. Various 32-bit timers, single or dual 10-bit

8 channel ADC(s), 10-bit DAC, PWM channels and 47 GPIO lines with up to nine edge or level sensitive external interrupt pins make these microcontrollers particularly suitable for industrial control and medical systems.

1.2 Features

•16/32-bit ARM7TDMI-S microcontroller in a tiny LQFP64 package

•8/16/32 kB of on-chip static RAM and 32/64/128/256/512 kB of on-chip Flash program memory. 128 bit wide interface/accelerator enables high speed 60 MHz operation.

•In-System/In-Application Programming (ISP/IAP) via on-chip boot-loader software. Single Flash sector or full chip erase in 400 ms and 256 bytes programming in 1 ms.

•EmbeddedICE® and Embedded Trace interfaces offer real-time debugging with the on-chip RealMonitor™ software and high speed tracing of instruction execution.

•One (LPC2131/2) or two (LPC2134/6/8) 8 channel 10-bit A/D converters provide(s) a total of up to 16 analog inputs, with conversion times as low as 2.44 µs per channel.

•Single 10-bit D/A converter provides variable analog output. (LPC2132/4/6/8 only).

•Two 32-bit timers/external event counters (with four capture and four compare channels each), PWM unit (six outputs) and watchdog.

•Low power Real-time clock with independent power and dedicated 32 kHz clock input.

•Multiple serial interfaces including two UARTs (16C550), two Fast I2C (400 kbit/s), SPI™ and SSP with buffering and variable data length capabilities.

•Vectored interrupt controller with configurable priorities and vector addresses.

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•Up to 47 of 5 V tolerant general purpose I/O pins in tiny LQFP64 package.

•Up to nine edge or level sensitive external interrupt pins available.

•60 MHz maximum CPU clock available from programmable on-chip Phase-Locked Loop (PLL) with settling time of 100 µs.

•On-chip integrated oscillator operates with external crystal in range of 1 MHz to 30 MHz or with external oscillator from 1 MHz to 50 MHz.

•Power saving modes include Idle and Power-down.

•Individual enable/disable of peripheral functions as well as peripheral clock scaling down for additional power optimization.

•Processor wake-up from Power-down mode via external interrupt or Real-time Clock.

•Single power supply chip with Power-On Reset (POR) and Brown-Out Detection (BOD) circuits:

–CPU operating voltage range of 3.0 V to 3.6 V (3.3 V ± 10 %) with 5 V tolerant I/O pads

1.3Applications

•Industrial control

•Medical systems

•Access control

•Point-of-sale

•Communication gateway

•Embedded soft modem

•General purpose applications

1.4Device information

Table 1:	LPC2131/2132/2134/2136/2138 device information
Device	Number of	On-chip	On-chip	Number of	Number of	Note
	pins	SRAM	FLASH	10-bit ADC	10-bit DAC
				channels	channels
LPC2131	64	8 kB	32 kB	8	-	-

LPC2132	64	16 kB	64 kB	8	1	-

LPC2134	64	16 kB	128 kB	16	1	UART1 with full
						modem interface

LPC2136	64	32 kB	256 kB	16	1	UART1 with full
						modem interface

LPC2138	64	32 kB	512 kB	16	1	UART1 with full
						modem interface

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1.5 Architectural overview

The LPC2131/2/4/6/8 consists of an ARM7TDMI-S CPU with emulation support, the ARM7 Local Bus for interface to on-chip memory controllers, the AMBA Advanced High-performance Bus (AHB) for interface to the interrupt controller, and the VLSI Peripheral Bus (VPB, a compatible superset of ARM’s AMBA Advanced Peripheral Bus) for connection to on-chip peripheral functions. The LPC2131/2/4/6/8 configures the ARM7TDMI-S processor in little-endian byte order.

AHB peripherals are allocated a 2 megabyte range of addresses at the very top of the

4 gigabyte ARM memory space. Each AHB peripheral is allocated a 16 kB address space within the AHB address space. LPC2131/2/4/6/8 peripheral functions (other than the interrupt controller) are connected to the VPB bus. The AHB to VPB bridge interfaces the VPB bus to the AHB bus. VPB peripherals are also allocated a 2 megabyte range of addresses, beginning at the 3.5 gigabyte address point. Each VPB peripheral is allocated a 16 kB address space within the VPB address space.

The connection of on-chip peripherals to device pins is controlled by a Pin Connect Block (see chapter "Pin Connect Block" on page 73). This must be configured by software to fit specific application requirements for the use of peripheral functions and pins.

1.6 ARM7TDMI-S processor

The ARM7TDMI-S is a general purpose 32-bit microprocessor, which offers high performance and very low power consumption. The ARM architecture is based on Reduced Instruction Set Computer (RISC) principles, and the instruction set and related decode mechanism are much simpler than those of microprogrammed Complex Instruction Set Computers. This simplicity results in a high instruction throughput and impressive real-time interrupt response from a small and cost-effective processor core.

Pipeline techniques are employed so that all parts of the processing and memory systems can operate continuously. Typically, while one instruction is being executed, its successor is being decoded, and a third instruction is being fetched from memory.

The ARM7TDMI-S processor also employs a unique architectural strategy known as THUMB, which makes it ideally suited to high-volume applications with memory restrictions, or applications where code density is an issue.

The key idea behind THUMB is that of a super-reduced instruction set. Essentially, the ARM7TDMI-S processor has two instruction sets:

•The standard 32-bit ARM instruction set.

•A 16-bit THUMB instruction set.

The THUMB set’s 16-bit instruction length allows it to approach twice the density of standard ARM code while retaining most of the ARM’s performance advantage over a traditional 16-bit processor using 16-bit registers. This is possible because THUMB code operates on the same 32-bit register set as ARM code.

THUMB code is able to provide up to 65% of the code size of ARM, and 160% of the performance of an equivalent ARM processor connected to a 16-bit memory system.

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The ARM7TDMI-S processor is described in detail in the ARM7TDMI-S Datasheet that can be found on official ARM website.

1.7 On-chip Flash memory system

The LPC2131/2/4/6/8 incorporates a 32, 64, 128, 256 and 512 kB Flash memory system respectively. This memory may be used for both code and data storage. Programming of the Flash memory may be accomplished in several ways: over the serial builtin JTAG interface, using In System Programming (ISP) and UART0, or by means of In Application Programming (IAP) capabilities. The application program, using the IAP functions, may also erase and/or program the Flash while the application is running, allowing a great degree of flexibility for data storage field firmware upgrades, etc. When the LPC2131/2/4/6/8 on-chip bootloader is used, 32/64/128/256/500 kB of Flash memory is available for user code.

The LPC2131/2/4/6/8 Flash memory provides minimum of 10,000 erase/write cycles and

10years of data-retention.

1.8On-chip Static RAM (SRAM)

On-chip Static RAM (SRAM) may be used for code and/or data storage. The on-chip SRAM may be accessed as 8-bits, 16-bits, and 32-bits. The LPC2131/2/4/6/8 provide 8/16/32 kB of static RAM respectively.

The LPC2131/2/4/6/8 SRAM is designed to be accessed as a byte-addressed memory. Word and halfword accesses to the memory ignore the alignment of the address and access the naturally-aligned value that is addressed (so a memory access ignores address bits 0 and 1 for word accesses, and ignores bit 0 for halfword accesses). Therefore valid reads and writes require data accessed as halfwords to originate from addresses with address line 0 being 0 (addresses ending with 0, 2, 4, 6, 8, A, C, and E in hexadecimal nottaion) and data accessed as words to originate from adresses with address lines 0 and 1 being 0 (addresses ending with 0, 4, 8, and C in hexadecimal notation). This rule applies to both off and on-chip memory usage.

The SRAM controller incorporates a write-back buffer in order to prevent CPU stalls during back-to-back writes. The write-back buffer always holds the last data sent by software to the SRAM. This data is only written to the SRAM when another write is requested by software (the data is only written to the SRAM when software does another write). If a chip reset occurs, actual SRAM contents will not reflect the most recent write request (i.e. after a "warm" chip reset, the SRAM does not reflect the last write operation). Any software that checks SRAM contents after reset must take this into account. Two identical writes to a location guarantee that the data will be present after a Reset. Alternatively, a dummy write operation before entering idle or power-down mode will similarly guarantee that the last data written will be present in SRAM after a subsequent Reset.

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Philips LPC2131, LPC2132, LPC2134, LPC2136, LPC2138 User Guide

Philips Semiconductors		UM10120
	Volume 1	Chapter 1: Introductory information

1.9 Block diagram

EINT3:0

8 × CAP0

8 × MAT

AD0.7:0

AD1.7:0(1)

AOUT(2)

P0.31:0 P1.31:16

PWM6:1

TMS(3) TDI(3)

XTAL2

TRST(3)

TCK(3)

TDO(3)

XTAL1

RST

LPC2131/2132/2134/2136/2138

TEST/DEBUG

EMULATIONTRACE MODULE

INTERFACE

PLL

SYSTEM

AHB BRIDGE

FUNCTIONS

INTERRUPT

ARM7TDMI-S

system

clock

VECTORED

CONTROLLER

ARM7 local bus

AMBA AHB

(Advanced High-performance Bus)

INTERNAL

SRAM

FLASH

CONTROLLER

AHB

DECODER

8/16/32 kB

32/64/128/

AHB TO VPB

VPB

SRAM

256/512 kB

BRIDGE

DIVIDER

FLASH

VPB (VLSI

peripheral bus)

SCL0,1

EXTERNAL

I2C SERIAL

INTERRUPTS

INTERFACES 0 AND 1

SDA0,1

SCK0,1

CAPTURE/

COMPARE

SPI AND SSP

MOSI0,1

TIMER 0/TIMER 1

SERIAL INTERFACES

MISO0,1

SSEL0,1

A/D CONVERTERS

0 AND 1(1)

D/A CONVERTER	(2)

GENERAL

PURPOSE I/O

PWM0

				TXD0,1
				TXD0,1
UART0/UART1				RXD0,1
				RXD0,1

DSR1(1),CTS1(1),

RTS1(1), DTR1(1)

DCD1(1),RI1(1)

RTXC1

REAL TIME CLOCK		RTXC2

VBAT

WATCHDOG

TIMER

SYSTEM

CONTROL

002aab067

(1)LPC2134/2136/2138 only.

(2)LPC2132/2134/2136/2138 only.

(3)Pins shared with GPIO.

Fig 1. LPC2131/2/4/6/8 block diagram

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UM10120

Chapter 2: LPC2131/2/4/6/8 Memory Addressing

Rev. 01 — 24 June 2005	User manual

2.1 Memory maps

The LPC2131/2/4/6/8 incorporates several distinct memory regions, shown in the following figures. Figure 2 shows the overall map of the entire address space from the user program viewpoint following reset. The interrupt vector area supports address remapping, which is described later in this section.

4.0 GB

3.75 GB

3.5 GB

3.0GB

2.0GB

1.0 GB

0.0 GB

AHB PERIPHERALS

VPB PERIPHERALS

RESERVED ADDRESS SPACE

BOOT BLOCK

(REMAPPED FROM ON-CHIP FLASH MEMORY)

RESERVED ADDRESS SPACE

32 kB ON-CHIP STATIC RAM (LPC2136/2138)

16 kB ON-CHIP STATIC RAM (LPC2132/2134)

8 kB ON-CHIP STATIC RAM (LPC2131)

RESERVED ADDRESS SPACE

TOTAL OF 512 kB ON-CHIP NON-VOLATILE MEMORY (LPC2138)

TOTAL OF 256 kB ON-CHIP NON-VOLATILE MEMORY (LPC2136)

TOTAL OF 128 kB ON-CHIP NON-VOLATILE MEMORY (LPC2134)

TOTAL OF 64 kB ON-CHIP NON-VOLATILE MEMORY (LPC2132)

TOTAL OF 32 kB ON-CHIP NON-VOLATILE MEMORY (LPC2131)

0xFFFF FFFF

0xF000 0000

0xE000 0000

0xC000 0000

0x8000 0000

0x4000 8000

0x4000 7FFF

0x4000 4000

0x4000 3FFF

0x4000 2000

0x4000 1FFF

0x4000 0000

0x0008 0000

0x0007 FFFF

0x0004 0000

0x0003 FFFF

0x0002 0000

0x0001 FFFF

0x0001 0000

0x0000 FFFF

0x0000 8000

0x0000 7FFF

0x0000 0000

Fig 2. System memory map

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	Volume 1	Chapter 2: Memory map

4.0 GB

4.0 GB - 2 MB

Notes:

-AHB section is 128 x 16 kB blocks (totaling 2 MB).

-VPB section is 128 x 16 kB blocks (totaling 2 MB).

0xFFFF FFFF

AHB PERIPHERALS

0xFFE0 0000 0xFFDF FFFF

RESERVED

3.75 GB

0xF000 0000 0xEFFF FFFF

RESERVED

3.5 GB + 2 MB		0xE020 0000
		0xE01F FFFF

	VPB PERIPHERALS
3.5 GB		0xE000 0000

Fig 3. Peripheral memory map

Figures 3 through 5 show different views of the peripheral address space. Both the AHB and VPB peripheral areas are 2 megabyte spaces which are divided up into 128 peripherals. Each peripheral space is 16 kilobytes in size. This allows simplifying the

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address decoding for each peripheral. All peripheral register addresses are word aligned (to 32-bit boundaries) regardless of their size. This eliminates the need for byte lane mapping hardware that would be required to allow byte (8-bit) or half-word (16-bit) accesses to occur at smaller boundaries. An implication of this is that word and half-word registers must be accessed all at once. For example, it is not possible to read or write the upper byte of a word register separately.

VECTORED INTERRUPT CONTROLLER

(AHB PERIPHERAL #126)

(AHB PERIPHERAL #125)

(AHB PERIPHERAL #124)

(AHB PERIPHERAL #3)

(AHB PERIPHERAL #2)

(AHB PERIPHERAL #1)

(AHB PERIPHERAL #0)

0xFFFF F000 (4G - 4K)

0xFFFF C000

0xFFFF 8000

0xFFFF 4000

0xFFFF 0000

0xFFE1 0000

0xFFE0 C000

0xFFE0 8000

0xFFE0 4000

0xFFE0 0000

Fig 4. AHB peripheral map

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	Volume 1	Chapter 2: Memory map

SYSTEM CONTROL BLOCK (VPB PERIPHERAL #127)

(VPB PERIPHERALS #28-126)

NOT USED

DAC

(VPB PERIPHERAL #27)

SSP

(VPB PERIPHERAL #26)

NOT USED

(VPB PERIPHERAL #25)

10 BIT AD1 (LPC2138) (VPB PERIPHERAL #24)

I2 C1

(VPB PERIPHERAL #23)

NOT USED

(VPB PERIPHERAL #14-22)

10 BIT ADO

(VPB PERIPHERAL #13)

NOT USED

(VPB PERIPHERAL #12)

PIN CONNECT BLOCK (VPB PERIPHERAL #11)

GPIO

(VPB PERIPHERAL #10)

RTC

(VPB PERIPHERAL #9)

SPI0

(VPB PERIPHERAL #8)

I2 C0

(VPB PERIPHERAL #7)

NOT USED

(VPB PERIPHERAL #6)

PWM

(VPB PERIPHERAL #5)

UART1

(VPB PERIPHERAL #4)

URT0

(VPB PERIPHERAL #3)

TIMER1

(VPB PERIPHERAL #2)

TIMER0

(VPB PERIPHERAL #1)

WATCHDOG TIMER (VPB PERIPHERAL #0)

0xE01F FFFF

0xE01F C000

0xE007 0000

0xE006 C000

0xE006 8000

0xE006 4000

0xE006 0000

0xE005 C000

0xE003 8000

0xE003 4000

0xE003 0000

0xE002 C000

0xE002 8000

0xE002 4000

0xE002 0000

0xE001 C000

0xE001 8000

0xE001 4000

0xE001 0000

0xE000 C000

0xE000 8000

0xE000 4000

0xE000 0000

Fig 5. VPB peripheral map

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2.2 LPC2131/2132/2134/2136/2138 memory re-mapping and boot block

2.2.1 Memory map concepts and operating modes

The basic concept on the LPC2131/2/4/6/8 is that each memory area has a "natural" location in the memory map. This is the address range for which code residing in that area is written. The bulk of each memory space remains permanently fixed in the same location, eliminating the need to have portions of the code designed to run in different address ranges.

Because of the location of the interrupt vectors on the ARM7 processor (at addresses 0x0000 0000 through 0x0000 001C, as shown in Table 2 below), a small portion of the Boot Block and SRAM spaces need to be re-mapped in order to allow alternative uses of interrupts in the different operating modes described in Table 3. Re-mapping of the interrupts is accomplished via the Memory Mapping Control feature (Section 3.6 “Memory mapping control” on page 25).

Table 2:		ARM exception vector locations
Address			Exception
0x0000	0000		Reset

0x0000	0004		Undefined Instruction

0x0000	0008		Software Interrupt

0x0000	000C		Prefetch Abort (instruction fetch memory fault)

0x0000	0010		Data Abort (data access memory fault)

0x0000	0014		Reserved
			Note: Identified as reserved in ARM documentation, this location is used
			by the Boot Loader as the Valid User Program key. This is descibed in
			detail in "Flash Memory System and Programming" chapter on page 216.

0x0000	0018		IRQ

0x0000	001C		FIQ

Table 3:		LPC2131/2/4/6/8 memory mapping modes

Mode		Activation		Usage
Boot		Hardware		The Boot Loader always executes after any reset. The Boot Block
Loader		activation by		interrupt vectors are mapped to the bottom of memory to allow
mode		any Reset		handling exceptions and using interrupts during the Boot Loading
				process.

User		Software		Activated by Boot Loader when a valid User Program Signature is
Flash		activation by		recognized in memory and Boot Loader operation is not forced.
mode		Boot code		Interrupt vectors are not re-mapped and are found in the bottom of the
				Flash memory.

User RAM		Software		Activated by a User Program as desired. Interrupt vectors are
mode		activation by		re-mapped to the bottom of the Static RAM.
		User program

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	Volume 1	Chapter 2: Memory map

2.2.2 Memory re-mapping

In order to allow for compatibility with future derivatives, the entire Boot Block is mapped to the top of the on-chip memory space. In this manner, the use of larger or smaller flash modules will not require changing the location of the Boot Block (which would require changing the Boot Loader code itself) or changing the mapping of the Boot Block interrupt vectors. Memory spaces other than the interrupt vectors remain in fixed locations.

Figure 6 shows the on-chip memory mapping in the modes defined above.

The portion of memory that is re-mapped to allow interrupt processing in different modes includes the interrupt vector area (32 bytes) and an additional 32 bytes, for a total of

64 bytes. The re-mapped code locations overlay addresses 0x0000 0000 through 0x0000 003F. A typical user program in the Flash memory can place the entire FIQ handler at address 0x0000 001C without any need to consider memory boundaries. The vector contained in the SRAM, external memory, and Boot Block must contain branches to the actual interrupt handlers, or to other instructions that accomplish the branch to the interrupt handlers.

There are three reasons this configuration was chosen:

1.To give the FIQ handler in the Flash memory the advantage of not having to take a memory boundary caused by the remapping into account.

2.Minimize the need to for the SRAM and Boot Block vectors to deal with arbitrary boundaries in the middle of code space.

3.To provide space to store constants for jumping beyond the range of single word branch instructions.

Re-mapped memory areas, including the Boot Block and interrupt vectors, continue to appear in their original location in addition to the re-mapped address.

Details on re-mapping and examples can be found in Section 3.6 “Memory mapping control” on page 25.

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12 kB BOOT BLOCK

(RE-MAPPED FROM TOP OF FLASH MEMORY)

(BOOT BLOCK INTERRUPT VECTORS)

RESERVED ADDRESSING SPACE

32 kB ON-CHIP SRAM

(SRAM INTERRUPT VECTORS)

RESERVED ADDRESSING SPACE

(12 kB BOOT BLOCK RE-MAPPED TO HIGHER ADDRESS RANGE)

512 kB FLASH MEMORY

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Volume 1

2.0 GB

2.0 GB - 12 kB

1.0 GB

Chapter 2: Memory map

0x8000 0000 0x7FFF FFFF

0x4000 8000

0x4000 7FFF

0x4000 0000 0x3FFF FFFF

0x0008 0000

0x0007 FFFF

0.0 GB	ACTIVE INTERRUPT VECTORS (FROM FLASH, SRAM, OR BOOT BLOCK)	0x0000 0000

Note: Memory regions are not drawn to scale.

Fig 6. Map of lower memory is showing re-mapped and re-mappable areas (LPC2138 with 512 kB Flash)

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2.3 Prefetch abort and data abort exceptions

The LPC2131/2/4/6/8 generates the appropriate bus cycle abort exception if an access is attempted for an address that is in a reserved or unassigned address region. The regions are:

•Areas of the memory map that are not implemented for a specific ARM derivative. For the LPC2131/2/4/6/8, this is:

–Address space between On-Chip Non-Volatile Memory and On-Chip SRAM, labelled "Reserved Address Space" in Figure 2 and Figure 6. For 32 kB Flash device this is memory address range from 0x0000 8000 to 0x3FFF FFFF, for 64 kB Flash device this is memory address range from 0x0001 0000 to 0x3FFF FFFF, for 128 kB Flash device this is memory address range from 0x0002 0000 to

0x3FFF FFFF, for 256 kB Flash device this is memory address range from 0x0004 0000 to 0x3FFF FFFF while for 512 kB Flash device this range is from 0x0008 0000 to 0x3FFF FFFF.

–Address space between On-Chip Static RAM and the Boot Block. Labelled "Reserved Address Space" in Figure 2. For 8 kB SRAM device this is memory address range from 0x4000 2000 to 0x7FFF CFFF, for 16 kB SRAM device this is memory address range from 0x4000 4000 to 0x7FFF CFFF, while for 32 kB SRAM device this range is from 0x4000 8000 to 0x7FFF CFFF.

–Address space between 0x8000 0000 and 0xDFFF FFFF, labelled "Reserved Adress Space".

–Reserved regions of the AHB and VPB spaces. See Figure 3.

•Unassigned AHB peripheral spaces. See Figure 4.

•Unassigned VPB peripheral spaces. See Figure 5.

For these areas, both attempted data access and instruction fetch generate an exception. In addition, a Prefetch Abort exception is generated for any instruction fetch that maps to an AHB or VPB peripheral address.

Within the address space of an existing VPB peripheral, a data abort exception is not generated in response to an access to an undefined address. Address decoding within each peripheral is limited to that needed to distinguish defined registers within the peripheral itself. For example, an access to address 0xE000 D000 (an undefined address within the UART0 space) may result in an access to the register defined at address 0xE000 C000. Details of such address aliasing within a peripheral space are not defined in the LPC2131/2/4/6/8 documentation and are not a supported feature.

Note that the ARM core stores the Prefetch Abort flag along with the associated instruction (which will be meaningless) in the pipeline and processes the abort only if an attempt is made to execute the instruction fetched from the illegal address. This prevents accidental aborts that could be caused by prefetches that occur when code is executed very near a memory boundary.

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Chapter 3: System Control Block

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3.1 Summary of system control block functions

The System Control Block includes several system features and control registers for a number of functions that are not related to specific peripheral devices. These include:

•Crystal Oscillator

•External Interrupt Inputs

•Memory Mapping Control

•PLL

•Power Control

•Reset

•VPB Divider

•Wakeup Timer

Each type of function has its own register(s) if any are required and unneeded bits are defined as reserved in order to allow future expansion. Unrelated functions never share the same register addresses

3.2 Pin description

Table 4 shows pins that are associated with System Control block functions.

Table 4:	Pin summary
Pin name	Pin	Pin description
	direction
X1	Input	Crystal Oscillator Input - Input to the oscillator and internal clock
		generator circuits

X2	Output	Crystal Oscillator Output - Output from the oscillator amplifier

EINT0	Input	External Interrupt Input 0 - An active low/high level or
		falling/rising edge general purpose interrupt input. This pin may be
		used to wake up the processor from Idle or Power-down modes.
		Pins P0.1 and P0.16 can be selected to perform EINT0 function.

EINT1	Input	External Interrupt Input 1 - See the EINT0 description above.
		Pins P0.3 and P0.14 can be selected to perform EINT1 function.
		Important: LOW level on pin P0.14 immediately after reset is
		considered as an external hardware request to start the ISP
		command handler. More details on ISP and Serial Boot Loader can
		be found in "Flash Memory System and Programming" chapter on
		page 216.

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		Table 4:	Pin summary

		Pin name	Pin	Pin description
			direction
		EINT2	Input	External Interrupt Input 2 - See the EINT0 description above.
				Pins P0.7 and P0.15 can be selected to perform EINT2 function.

		EINT3	Input	External Interrupt Input 3 - See the EINT0 description above.
				Pins P0.9, P0.20 and P0.30 can be selected to perform EINT3
				function.

			Input	External Reset input - A LOW on this pin resets the chip, causing
		RESET	Input
				I/O ports and peripherals to take on their default states, and the
				processor to begin execution at address 0x0000 0000.

3.3 Register description

All registers, regardless of size, are on word address boundaries. Details of the registers appear in the description of each function.

Table 5: Summary of system control registers

Name	Description	Access	Reset	Address
			value[1]
External Interrupts

EXTINT	External Interrupt Flag Register	R/W	0	0xE01F C140

EXTWAKE	External Interrupt Wakeup Register	R/W	0	0xE01F C144

EXTMODE	External Interrupt Flag register	R/W	0	0xE01F C148

EXTPOLAR	External Interrupt Wakeup Register	R/W	0	0xE01F C14C

Memory Mapping Control

MEMMAP	Memory Mapping Control	R/W	0	0xE01F C040

Phase Locked Loop

PLLCON	PLL Control Register	R/W	0	0xE01F C080

PLLCFG	PLL Configuration Register	R/W	0	0xE01F C084

PLLSTAT	PLL Status Register	RO	0	0xE01F C088

PLLFEED	PLL Feed Register	WO	NA	0xE01F C08C

Power Control

PCON	Power Control Register	R/W	0	0xE01F C0C0

PCONP	Power Control for Peripherals	R/W	0x03BE	0xE01F C0C4

VPB Divider

VPBDIV	VPB Divider Control	R/W	0	0xE01F C100

Reset

RSID	Reset Source Identification Register	R/W	0	0xE01F C180

Code Security/Debugging

CSPR	Code Security Protection Register	RO	o	0xE01F C184

[1]Reset value relects the data stored in used bits only. It does not include reserved bits content.

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3.4 Crystal oscillator

While an input signal of 50-50 duty cycle within a frequency range from 1 MHz to 50 MHz can be used by the LPC2131/2/4/6/8 if supplied to its input XTAL1 pin, this microcontroller’s onboard oscillator circuit supports external crystals in the range of 1 MHz to 30 MHz only. If the on-chip PLL system or the boot-loader is used, the input clock frequency is limited to an exclusive range of 10 MHz to 25 MHz.

The oscillator output frequency is called FOSC and the ARM processor clock frequency is referred to as CCLK for purposes of rate equations, etc. elsewhere in this document. FOSC and CCLK are the same value unless the PLL is running and connected. Refer to the Section 3.7 “Phase Locked Loop (PLL)” on page 26 for details and frequency limitations.

The onboard oscillator in the LPC2131/2/4/6/8 can operate in one of two modes: slave mode and oscillation mode.

In slave mode the input clock signal should be coupled by means of a capacitor of 100 pF (CC in Figure 7, drawing a), with an amplitude of at least 200 mVrms. The X2 pin in this configuration can be left not connected. If slave mode is selected, the FOSC signal of 50-50 duty cycle can range from 1 MHz to 50 MHz.

External components and models used in oscillation mode are shown in Figure 7, drawings b and c, and in Table 6. Since the feedback resistance is integrated on chip, only a crystal and the capacitances CX1 and CX2 need to be connected externally in case of fundamental mode oscillation (the fundamental frequency is represented by L, CL and RS). Capacitance CP in Figure 7, drawing c, represents the parallel package capacitance and should not be larger than 7 pF. Parameters FC, CL, RS and CP are supplied by the crystal manufacturer.

Choosing an oscillation mode as an on-board oscillator mode of operation limits FOSC clock selection to 1 MHz to 30 MHz.

LPC2131/2/4/6/8		LPC2131/2/4/6/8
X1	X2	X1	X2
						L
	CC				< = >	C	C
	CC					C	C
						L	P
	Clock	CX1	Xtal	CX2
	Clock	CX1		CX2		RS
						RS

Fig 7. Oscillator modes and models: a) slave mode of operation, b) oscillation mode of operation, c) external crystal model used for CX1/X2 evaluation

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		Table 6: Recommended values for CX1/X2 in oscillation mode (crystal and external
		components parameters)

		Fundamental	Crystal load	Maximum crystal	External load
		oscillation frequency	capacitance CL	series resistance RS	capacitors CX1, CX2
		FC
		1 MHz - 5 MHz	10 pF	NA	NA

			20 pF	NA	NA

			30 pF	< 300 Ω	58 pF, 58 pF

		5 MHz - 10 MHz	10 pF	< 300 Ω	18 pF, 18 pF

			20 pF	< 300 Ω	38 pF, 38 pF

			30 pF	< 300 Ω	58 pF, 58 pF

		10 MHz - 15 MHz	10 pF	< 300 Ω	18 pF, 18 pF

			20 pF	< 220 Ω	38 pF, 38 pF

			30 pF	< 140 Ω	58 pF, 58 pF

		15 MHz - 20 MHz	10 pF	< 220 Ω	18 pF, 18 pF

			20 pF	< 140 Ω	38 pF, 38 pF

			30 pF	< 80 Ω	58 pF, 58 pF

		20 MHz - 25 MHz	10 pF	< 160 Ω	18 pF, 18 pF

			20 pF	< 90 Ω	38 pF, 38 pF

			30 pF	< 50 Ω	58 pF, 58 pF

		25 MHz - 30 MHz	10 pF	< 130 Ω	18 pF, 18 pF

			20 pF	< 50 Ω	38 pF, 38 pF

			30 pF	NA	NA

	f OSC selection
True	On-chip PLL used
	On-chip PLL used
	in application?
		False
True	ISP used for initial
	ISP used for initial
	code download?
		False
	External crystal		True
	External crystal
	oscillator used?
		False
MIN f = 10 MHz	MIN f	= 1 MHz	MIN f	= 1 MHz
OSC	OSC		OSC
MAX fOSC = 25 MHz	MAX fOSC = 50 MHz		MAX fOSC = 30 MHz
(Figure 7, mode a and/or b)	(Figure 7, mode a)		(Figure 7, mode b)
Fig 8. FOSC selection algorithm

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3.5 External interrupt inputs

The LPC2131/2/4/6/8 includes four External Interrupt Inputs as selectable pin functions. The External Interrupt Inputs can optionally be used to wake up the processor from Power-down mode.

3.5.1 Register description

The external interrupt function has four registers associated with it. The EXTINT register contains the interrupt flags, and the EXTWAKEUP register contains bits that enable individual external interrupts to wake up the microcontroller from Power-down mode. The EXTMODE and EXTPOLAR registers specify the level and edge sensitivity parameters.

Table 7: External interrupt registers

Name	Description	Access	Reset	Address
			value[1]
EXTINT	The External Interrupt Flag Register contains	R/W	0	0xE01F C140
	interrupt flags for EINT0, EINT1, EINT2 and
	EINT3. See Table 8.

INTWAKE	The Interrupt Wakeup Register contains four	R/W	0	0xE01F C144
	enable bits that control whether each external
	interrupt will cause the processor to wake up
	from Power-down mode. See Table 9.

EXTMODE	The External Interrupt Mode Register controls	R/W	0	0xE01F C148
	whether each pin is edgeor levelsensitive.

EXTPOLAR	The External Interrupt Polarity Register controls	R/W	0	0xE01F C14C
	which level or edge on each pin will cause an
	interrupt.

[1]Reset value relects the data stored in used bits only. It does not include reserved bits content.

3.5.2External Interrupt Flag register (EXTINT - 0xE01F C140)

When a pin is selected for its external interrupt function, the level or edge on that pin (selected by its bits in the EXTPOLAR and EXTMODE registers) will set its interrupt flag in this register. This asserts the corresponding interrupt request to the VIC, which will cause an interrupt if interrupts from the pin are enabled.

Writing ones to bits EINT0 through EINT3 in EXTINT register clears the corresponding bits. In level-sensitive mode this action is efficacious only when the pin is in its inactive state.

Once a bit from EINT0 to EINT3 is set and an appropriate code starts to execute (handling wakeup and/or external interrupt), this bit in EXTINT register must be cleared. Otherwise the event that was just triggered by activity on the EINT pin will not be recognized in the future.

Important: whenever a change of external interrupt operating mode (i.e. active level/edge) is performed (including the initialization of an external interrupt), the corresponding bit in the EXTINT register must be cleared! For details see Section 3.5.4 “External Interrupt Mode register (EXTMODE - 0xE01F C148)” and Section 3.5.5 “External Interrupt Polarity register (EXTPOLAR - 0xE01F C14C)”.

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For example, if a system wakes up from power-down using a low level on external interrupt 0 pin, its post-wakeup code must reset the EINT0 bit in order to allow future entry into the power-down mode. If the EINT0 bit is left set to 1, subsequent attempt(s) to invoke power-down mode will fail. The same goes for external interrupt handling.

More details on power-down mode will be discussed in the following chapters.

Table 8: External Interrupt Flag register (EXTINT - address 0xE01F C140) bit description

Bit	Symbol	Description	Reset
			value

0	EINT0	In level-sensitive mode, this bit is set if the EINT0 function is selected for its pin, and the pin is in	0
		its active state. In edge-sensitive mode, this bit is set if the EINT0 function is selected for its pin,
		and the selected edge occurs on the pin.
		Up to two pins can be selected to perform the EINT0 function (see P0.1 and P0.16 description in
		"Pin Configuration" chapter page 64.)
		This bit is cleared by writing a one to it, except in level sensitive mode when the pin is in its active
		state (e.g. if EINT0 is selected to be low level sensitive and a low level is present on the
		corresponding pin, this bit can not be cleared; this bit can be cleared only when the signal on the
		pin becomes high).

1	EINT1	In level-sensitive mode, this bit is set if the EINT1 function is selected for its pin, and the pin is in	0
		its active state. In edge-sensitive mode, this bit is set if the EINT1 function is selected for its pin,
		and the selected edge occurs on the pin.
		Up to two pins can be selected to perform the EINT1 function (see P0.3 and P0.14 description in
		"Pin Configuration" chapter on page 64.)
		This bit is cleared by writing a one to it, except in level sensitive mode when the pin is in its active
		state (e.g. if EINT1 is selected to be low level sensitive and a low level is present on the
		corresponding pin, this bit can not be cleared; this bit can be cleared only when the signal on the
		pin becomes high).

2	EINT2	In level-sensitive mode, this bit is set if the EINT2 function is selected for its pin, and the pin is in	0
		its active state. In edge-sensitive mode, this bit is set if the EINT2 function is selected for its pin,
		and the selected edge occurs on the pin.
		Up to two pins can be selected to perform the EINT2 function (see P0.7 and P0.15 description in
		"Pin Configuration" chapter on page 64.)
		This bit is cleared by writing a one to it, except in level sensitive mode when the pin is in its active
		state (e.g. if EINT2 is selected to be low level sensitive and a low level is present on the
		corresponding pin, this bit can not be cleared; this bit can be cleared only when the signal on the
		pin becomes high).

3	EINT3	In level-sensitive mode, this bit is set if the EINT3 function is selected for its pin, and the pin is in	0
		its active state. In edge-sensitive mode, this bit is set if the EINT3 function is selected for its pin,
		and the selected edge occurs on the pin.
		Up to three pins can be selected to perform the EINT3 function (see P0.9, P0.20 and P0.30
		description in "Pin Configuration" chapter on page 64.)
		This bit is cleared by writing a one to it, except in level sensitive mode when the pin is in its active
		state (e.g. if EINT3 is selected to be low level sensitive and a low level is present on the
		corresponding pin, this bit can not be cleared; this bit can be cleared only when the signal on the
		pin becomes high).

7:4	-	Reserved, user software should not write ones to reserved bits. The value read from a reserved	NA
		bit is not defined.

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3.5.3 Interrupt Wakeup register (INTWAKE - 0xE01F C144)

Enable bits in the INTWAKE register allow the external interrupts to wake up the processor if it is in Power-down mode. The related EINTn function must be mapped to the pin in order for the wakeup process to take place. It is not necessary for the interrupt to be enabled in the Vectored Interrupt Controller for a wakeup to take place. This arrangement allows additional capabilities, such as having an external interrupt input wake up the processor from Power-down mode without causing an interrupt (simply resuming operation), or allowing an interrupt to be enabled during Power-down without waking the processor up if it is asserted (eliminating the need to disable the interrupt if the wakeup feature is not desirable in the application).

For an external interrupt pin to be a source that would wake up the microcontroller from Power-down mode, it is also necessary to clear the corresponding bit in the External Interrupt Flag register (Section 3.5.2 on page 20).

Table 9: Interrupt Wakeup register (INTWAKE - address 0xE01F C144) bit description

Bit	Symbol	Description	Reset
			value

0	EXTWAKE0	When one, assertion of EINT0 will wake up the processor from	0
		Power-down mode.

1	EXTWAKE1	When one, assertion of EINT1 will wake up the processor from	0
		Power-down mode.

2	EXTWAKE2	When one, assertion of EINT2 will wake up the processor from	0
		Power-down mode.

3	EXTWAKE3	When one, assertion of EINT3 will wake up the processor from	0
		Power-down mode.

13:4	-	Reserved, user software should not write ones to reserved bits.	NA
		The value read from a reserved bit is not defined.

14	BODWAKE	When one, a BOD interrupt will wake up the processor from	0
		Power-down mode.

15	RTCWAKE	When one, assertion of an RTC interrupt will wake up the	0
		processor from Power-down mode.

3.5.4 External Interrupt Mode register (EXTMODE - 0xE01F C148)

The bits in this register select whether each EINT pin is levelor edge-sensitive. Only pins that are selected for the EINT function (see chapter Pin Connect Block on page 73) and enabled via the VICIntEnable register (Section 5.4.4 “Interrupt Enable register (VICIntEnable - 0xFFFF F010)” on page 52) can cause interrupts from the External Interrupt function (though of course pins selected for other functions may cause interrupts from those functions).

Note: Software should only change a bit in this register when its interrupt is disabled in the VICIntEnable register, and should write the corresponding 1 to the EXTINT register before enabling (initializing) or re-enabling the interrupt, to clear the EXTINT bit that could be set by changing the mode.

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		Table 10: External Interrupt Mode register (EXTMODE - address 0xE01F C148) bit
			description

		Bit	Symbol	Value	Description	Reset
						value

0			EXTMODE0	0	Level-sensitivity is selected for EINT0.	0

				1	EINT0 is edge sensitive.

1			EXTMODE1	0	Level-sensitivity is selected for EINT1.	0

				1	EINT1 is edge sensitive.

2			EXTMODE2	0	Level-sensitivity is selected for EINT2.	0

				1	EINT2 is edge sensitive.

3			EXTMODE3	0	Level-sensitivity is selected for EINT3.	0

				1	EINT3 is edge sensitive.

7:4			-	-	Reserved, user software should not write ones to reserved	NA
					bits. The value read from a reserved bit is not defined.

3.5.5 External Interrupt Polarity register (EXTPOLAR - 0xE01F C14C)

In level-sensitive mode, the bits in this register select whether the corresponding pin is highor low-active. In edge-sensitive mode, they select whether the pin is risingor falling-edge sensitive. Only pins that are selected for the EINT function (see "Pin Connect Block" chapter on page 73) and enabled in the VICIntEnable register (Section 5.4.4 “Interrupt Enable register (VICIntEnable - 0xFFFF F010)” on page 52) can cause interrupts from the External Interrupt function (though of course pins selected for other functions may cause interrupts from those functions).

Table 11: External Interrupt Polarity register (EXTPOLAR - address 0xE01F C14C) bit description

Bit	Symbol	Value	Description	Reset
				value
0	EXTPOLAR0	0	EINT0 is low-active or falling-edge sensitive (depending on	0
			EXTMODE0).

		1	EINT0 is high-active or rising-edge sensitive (depending on
			EXTMODE0).

1	EXTPOLAR1	0	EINT1 is low-active or falling-edge sensitive (depending on	0
			EXTMODE1).

		1	EINT1 is high-active or rising-edge sensitive (depending on
			EXTMODE1).

2	EXTPOLAR2	0	EINT2 is low-active or falling-edge sensitive (depending on	0
			EXTMODE2).

		1	EINT2 is high-active or rising-edge sensitive (depending on
			EXTMODE2).

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		Table 11: External Interrupt Polarity register (EXTPOLAR - address 0xE01F C14C) bit
			description

		Bit	Symbol	Value	Description	Reset
						value
3			EXTPOLAR3	0	EINT3 is low-active or falling-edge sensitive (depending on	0
					EXTMODE3).

				1	EINT3 is high-active or rising-edge sensitive (depending on
					EXTMODE3).

7:4			-	-	Reserved, user software should not write ones to reserved	NA
					bits. The value read from a reserved bit is not defined.

3.5.6 Multiple external interrupt pins

Software can select multiple pins for each of EINT3:0 in the Pin Select registers, which are described in chapter Pin Connect Block on page 73. The external interrupt logic for each of EINT3:0 receives the state of all of its associated pins from the pins’ receivers, along with signals that indicate whether each pin is selected for the EINT function. The external interrupt logic handles the case when more than one pin is so selected, differently according to the state of its Mode and Polarity bits:

•In Low-Active Level Sensitive mode, the states of all pins selected for the same EINTx functionality are digitally combined using a positive logic AND gate.

•In High-Active Level Sensitive mode, the states of all pins selected for the same EINTx functionality are digitally combined using a positive logic OR gate.

•In Edge Sensitive mode, regardless of polarity, the pin with the lowest GPIO port number is used. (Selecting multiple pins for an EINTx in edge-sensitive mode could be considered a programming error.)

The signal derived by this logic is the EINTi signal in the following logic schematic

Figure 9.

For example, if the EINT3 function is selected in the PINSEL0 and PINSEL1 registers for pins P0.9, P0.20 and P0.30, and EINT3 is configured to be low level sensitive, the inputs from all three pins will be logically ANDed. When more than one EINT pin is logically ORed, the interrupt service routine can read the states of the pins from the GPIO port using the IO0PIN and IO1PIN registers, to determine which pin(s) caused the interrupt.

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Wakeup enable

VPB Read

(one bit of EXTWAKE)

of EXTWAKE

VPB Bus Data

EINTi to

Wakeup Timer

(Figure 11)

EINTi

GLITCH

PCLK

FILTER

EXTPOLARi				Interrupt Flag
EXTPOLARi				(one bit of EXTINT)
				(one bit of EXTINT)
1	D	S	S	S
1	D		S	S
		Q	Q	Q
EXTMODEi		R	R	R
EXTMODEi		R
			PCLK	PCLK
Reset
Write 1 to EXTINTi

Fig 9. External interrupt logic

3.6 Memory mapping control

The Memory Mapping Control alters the mapping of the interrupt vectors that appear beginning at address 0x0000 0000. This allows code running in different memory spaces to have control of the interrupts.

3.6.1 Memory Mapping control register (MEMMAP - 0xE01F C040)

Whenever an exception handling is necessary, the microcontroller will fetch an instruction residing on the exception corresponding address as described in Table 2 “ARM exception vector locations” on page 12. The MEMMAP register determines the source of data that will fill this table.

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		Table 12: Memory Mapping control register (MEMMAP - address 0xE01F C040) bit
			description

		Bit	Symbol	Value	Description	Reset
						value

1:0			MAP	00	Boot Loader Mode. Interrupt vectors are re-mapped to Boot	00
					Block.

				01	User Flash Mode. Interrupt vectors are not re-mapped and
					reside in Flash.

				10	User RAM Mode. Interrupt vectors are re-mapped to Static
					RAM.

				11	Reserved. Do not use this option.

Warning: Improper setting of this value may result in incorrect operation of the device.

7:2	-	-	Reserved, user software should not write ones to reserved	NA
			bits. The value read from a reserved bit is not defined.

3.6.2 Memory mapping control usage notes

The Memory Mapping Control simply selects one out of three available sources of data (sets of 64 bytes each) necessary for handling ARM exceptions (interrupts).

For example, whenever a Software Interrupt request is generated, the ARM core will always fetch 32-bit data "residing" on 0x0000 0008 see Table 2 “ARM exception vector locations” on page 12. This means that when MEMMAP[1:0]=10 (User RAM Mode), a read/fetch from 0x0000 0008 will provide data stored in 0x4000 0008. In case of MEMMAP[1:0]=00 (Boot Loader Mode), a read/fetch from 0x0000 0008 will provide data available also at 0x7FFF E008 (Boot Block remapped from on-chip Bootloader).

3.7 Phase Locked Loop (PLL)

The PLL accepts an input clock frequency in the range of 10 MHz to 25 MHz only. The input frequency is multiplied up into the CCLK with the range of 10 MHz to 60 MHz using a Current Controlled Oscillator (CCO). The multiplier can be an integer value from 1 to 32 (in practice, the multiplier value cannot be higher than 6 on the LPC2131/2/4/6/8 due to the upper frequency limit of the CPU). The CCO operates in the range of 156 MHz to 320 MHz, so there is an additional divider in the loop to keep the CCO within its frequency range while the PLL is providing the desired output frequency. The output divider may be set to divide by 2, 4, 8, or 16 to produce the output clock. Since the minimum output divider value is 2, it is insured that the PLL output has a 50% duty cycle. A block diagram of the PLL is shown in Figure 10.

PLL activation is controlled via the PLLCON register. The PLL multiplier and divider values are controlled by the PLLCFG register. These two registers are protected in order to prevent accidental alteration of PLL parameters or deactivation of the PLL. Since all chip operations, including the Watchdog Timer, are dependent on the PLL when it is providing the chip clock, accidental changes to the PLL setup could result in unexpected behavior of the microcontroller. The protection is accomplished by a feed sequence similar to that of the Watchdog Timer. Details are provided in the description of the PLLFEED register.

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The PLL is turned off and bypassed following a chip Reset and when by entering Power-down mode. The PLL is enabled by software only. The program must configure and activate the PLL, wait for the PLL to Lock, then connect to the PLL as a clock source.

3.7.1 Register description

The PLL is controlled by the registers shown in Table 13. More detailed descriptions follow.

Warning: Improper setting of the PLL values may result in incorrect operation of the device!

Table 13:	PLL registers
Name	Description	Access	Reset	Address
			value[1]
PLLCON	PLL Control Register. Holding register for	R/W	0	0xE01F C080
	updating PLL control bits. Values written to this
	register do not take effect until a valid PLL feed
	sequence has taken place.

PLLCFG	PLL Configuration Register. Holding register for	R/W	0	0xE01F C084
	updating PLL configuration values. Values
	written to this register do not take effect until a
	valid PLL feed sequence has taken place.

PLLSTAT	PLL Status Register. Read-back register for	RO	0	0xE01F C088
	PLL control and configuration information. If
	PLLCON or PLLCFG have been written to, but
	a PLL feed sequence has not yet occurred, they
	will not reflect the current PLL state. Reading
	this register provides the actual values
	controlling the PLL, as well as the status of the
	PLL.

PLLFEED	PLL Feed Register. This register enables	WO	NA	0xE01F C08C
	loading of the PLL control and configuration
	information from the PLLCON and PLLCFG
	registers into the shadow registers that actually
	affect PLL operation.

[1]Reset value relects the data stored in used bits only. It does not include reserved bits content.

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PLLC			CLOCK
			CLOCK
		SYNCHRONIZATION
0	Direct
PSEL[1:0]
	PD		PD
PLLE	Bypass
0	Bypass
F OSC				1	CD
	PHASE-				CD
	PHASE-		FCCO
	FREQUENCY	CCO	FCCO	0		0
PLOCK	FREQUENCY	CCO		0	/2P	0
PLOCK	DETECTOR				/2P	0	CCLK
						0	CCLK
						1
	PD					1
	PD
	CD
	FOUT
	DIV-BY-M
	MSEL<4:0>
MSEL[4:0]
Fig 10. PLL block diagram

3.7.2 PLL Control register (PLLCON - 0xE01F C080)

The PLLCON register contains the bits that enable and connect the PLL. Enabling the PLL allows it to attempt to lock to the current settings of the multiplier and divider values. Connecting the PLL causes the processor and all chip functions to run from the PLL output clock. Changes to the PLLCON register do not take effect until a correct PLL feed sequence has been given (see Section 3.7.7 “PLL Feed register (PLLFEED -

0xE01F C08C)” and Section 3.7.3 “PLL Configuration register (PLLCFG - 0xE01F C084)” on page 29).

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		Table 14: PLL Control register (PLLCON - address 0xE01F C080) bit description

		Bit	Symbol	Description	Reset
					value
0			PLLE	PLL Enable. When one, and after a valid PLL feed, this bit will	0
				activate the PLL and allow it to lock to the requested frequency. See
				PLLSTAT register, Table 16.

1			PLLC	PLL Connect. When PLLC and PLLE are both set to one, and after a	0
				valid PLL feed, connects the PLL as the clock source for the
				microcontroller. Otherwise, the oscillator clock is used directly by the
				microcontroller. See PLLSTAT register, Table 16.

7:2			-	Reserved, user software should not write ones to reserved bits. The	NA
				value read from a reserved bit is not defined.

The PLL must be set up, enabled, and Lock established before it may be used as a clock source. When switching from the oscillator clock to the PLL output or vice versa, internal circuitry synchronizes the operation in order to ensure that glitches are not generated.

Hardware does not insure that the PLL is locked before it is connected or automatically disconnect the PLL if lock is lost during operation. In the event of loss of PLL lock, it is likely that the oscillator clock has become unstable and disconnecting the PLL will not remedy the situation.

3.7.3 PLL Configuration register (PLLCFG - 0xE01F C084)

The PLLCFG register contains the PLL multiplier and divider values. Changes to the PLLCFG register do not take effect until a correct PLL feed sequence has been given (see Section 3.7.7 “PLL Feed register (PLLFEED - 0xE01F C08C)” on page 30). Calculations for the PLL frequency, and multiplier and divider values are found in the PLL Frequency Calculation section on page 31.

Table 15: PLL Configuration register (PLLCFG - address 0xE01F C084) bit description

Bit	Symbol	Description	Reset
			value
4:0	MSEL	PLL Multiplier value. Supplies the value "M" in the PLL frequency	0
		calculations.
		Note: For details on selecting the right value for MSEL see Section
		3.7.9 “PLL frequency calculation” on page 31.

6:5	PSEL	PLL Divider value. Supplies the value "P" in the PLL frequency	0
		calculations.
		Note: For details on selecting the right value for PSEL see Section
		3.7.9 “PLL frequency calculation” on page 31.

7	-	Reserved, user software should not write ones to reserved bits. The	NA
		value read from a reserved bit is not defined.

3.7.4 PLL Status register (PLLSTAT - 0xE01F C088)

The read-only PLLSTAT register provides the actual PLL parameters that are in effect at the time it is read, as well as the PLL status. PLLSTAT may disagree with values found in PLLCON and PLLCFG because changes to those registers do not take effect until a proper PLL feed has occurred (see Section 3.7.7 “PLL Feed register (PLLFEED - 0xE01F C08C)”).

User manual

Rev. 01 — 24 June 2005

Philips Semiconductors				UM10120
	Volume 1			Chapter 3: System Control Block
		Table 16: PLL Status register (PLLSTAT - address 0xE01F C088) bit description

		Bit	Symbol	Description	Reset
					value
4:0			MSEL	Read-back for the PLL Multiplier value. This is the value currently	0
				used by the PLL.

6:5			PSEL	Read-back for the PLL Divider value. This is the value currently	0
				used by the PLL.

7			-	Reserved, user software should not write ones to reserved bits.	NA
				The value read from a reserved bit is not defined.

8			PLLE	Read-back for the PLL Enable bit. When one, the PLL is currently	0
				activated. When zero, the PLL is turned off. This bit is automatically
				cleared when Power-down mode is activated.

9			PLLC	Read-back for the PLL Connect bit. When PLLC and PLLE are both	0
				one, the PLL is connected as the clock source for the
				microcontroller. When either PLLC or PLLE is zero, the PLL is
				bypassed and the oscillator clock is used directly by the
				microcontroller. This bit is automatically cleared when Power-down
				mode is activated.

10			PLOCK	Reflects the PLL Lock status. When zero, the PLL is not locked.	0
				When one, the PLL is locked onto the requested frequency.

15:11			-	Reserved, user software should not write ones to reserved bits.	NA
				The value read from a reserved bit is not defined.

3.7.5 PLL Interrupt

The PLOCK bit in the PLLSTAT register is connected to the interrupt controller. This allows for software to turn on the PLL and continue with other functions without having to wait for the PLL to achieve lock. When the interrupt occurs (PLOCK = 1), the PLL may be connected, and the interrupt disabled.

3.7.6 PLL Modes

The combinations of PLLE and PLLC are shown in Table 17.

Table 17: PLL Control bit combinations

PLLC	PLLE	PLL Function
0	0	PLL is turned off and disconnected. The system runs from the unmodified clock
		input.

0	1	The PLL is active, but not yet connected. The PLL can be connected after
		PLOCK is asserted.

1	0	Same as 00 combination. This prevents the possibility of the PLL being
		connected without also being enabled.

1	1	The PLL is active and has been connected as the system clock source.

3.7.7 PLL Feed register (PLLFEED - 0xE01F C08C)

A correct feed sequence must be written to the PLLFEED register in order for changes to the PLLCON and PLLCFG registers to take effect. The feed sequence is:

1.Write the value 0xAA to PLLFEED.

2.Write the value 0x55 to PLLFEED.

User manual

Rev. 01 — 24 June 2005

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