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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
484 of 571
NXP Semiconductors
UM10316
Chapter 28: LPC29xx Flash/EEPROM
A write operation causes an automatic post-increment of the address. This allows
consecutive writes to the page register without the need of writing a new address for every
write operation. Of course the address register could be written with another address
value to write to another location.
If the data register is written while a previous EEPROM operation is still pending, the write
transfer on the system bus is stalled by de-asserting the ready signal until the previous
operation is finished. This can be avoided by polling the interrupt status register to see if
an operation is still pending before starting the write operation. Polling is only sensible for
systems running at a high frequency (>200 MHz).
Software has to make sure that the following rules are followed:
•
Overwriting (writing it two times before a erase/program operation) one of the
locations in a 64-byte page register is not allowed, it will cause the loss of the
previously written data.
Fig 123. Starting a write operation
write address register
write address register
- or -
write command register
write command register
write data register
write data register
write operation
o n E E P R O M
now starts
Fig 124. Write operations with post-incrementing of address
w r i t e a d d r e s s r e g i s t e r
(address A)
w r i t e a d d r e s s r e g i s t e r
(address A)
- or -
write command register
write data register
write data register
write operation
o n E E P R O M
now starts
write command register
(16-bit write)
write data register
write data register
write operation
on EEPROM now
starts
write data register
write data register
write operation
on EEPROM now
starts
address A
address A+2
address A+4