LPC2921 datasheet(18/81 Pages) PHILIPS

18 / 81 page

LPC2921_2923_2925_0

Preliminary data sheet

Rev. 00.01 — 24 October 2008

18 of 81

NXP Semiconductors

LPC2921/2923/2925

ARM9 microcontroller with CAN and LIN

6.8.2 Flash layout

The ARM processor can program the flash for ISP (In-System Programming) through the

flash memory controller. Note that the flash always has to be programmed by ‘flash words’

of 128 bits (four 32-bit AHB bus words, hence 16 bytes).

The flash memory is organized into eight ‘small’ sectors of 8 kB each and up to 11 ‘large’

sectors of 64 kB each. The number of large sectors depends on the device type. A sector

must be erased before data can be written to it. The flash memory also has sector-wise

protection. Writing occurs per page which consists of 4096 bits (32 flash words). A small

sector contains 16 pages; a large sector contains 128 pages.

Table 10 gives an overview of the flash-sector base addresses.

Table 9.

Flash read modes

Synchronous timing

No buffer line

for single (non-linear) reads; one flash-word read per word read

Single buffer line

default mode of operation; most recently read flash word is kept until

another flash word is required

Asynchronous timing

No buffer line

one flash-word read per word read

Single buffer line

most recently read flash word is kept until another flash word is

required

Dual buffer line, single

speculative

on a buffer miss a flash read is done, followed by at most one

speculative read; optimized for execution of code with small loops

(less than eight words) from flash

Dual buffer line, always

speculative

most recently used flash word is copied into second buffer line; next

flash-word read is started; highest performance for linear reads

Table 10.

Flash sector overview

Flash memory

sector number

Sector size (kB)

Flash memory

address

LPC2921

LPC2923

LPC2925

2000 0000h

yes

2000 2000h

yes

2000 4000h

yes

2000 6000h

yes

2000 8000h

yes

2000 A000h

yes

2000 C000h

yes

2000 E000h

yes

2001 0000h

yes

2002 0000h

yes

2003 0000h

yes

2004 0000h

yes

2005 0000h

yes

2006 0000h

yes

2007 0000h

yes

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