PM0020 datasheet(22/87 Pages) STMICROELECTRONICS

22 / 87 page

STR91xFA Flash memory

PM00020

22/87

1.12

Write operations

When programming or writing to a Flash Bank, typically a "write" CUI command is issued

and followed by a "read" status register command. This "write" then "read" order must be

followed to program the Flash properly.

Caution:

This requires bit 18 (Instruction TCM order bit) in the Configuration Control Register of the

ARM966E-S core to be set. This can be done by the following assembler code :

MOV R0, #0x40000

MCR P15,0x1,R0,C15,C1,0

When set, the write and read to the Flash Bank are performed in the order generated by the

ARM966-ES core.This ensures that writes are committed to the Flash memory before any

subsequent read.

1.12.1

SE sector erase setup (20h)

Erasing a sector sets all the bits in the selected sector to '1'. You can erase one sector at a

time. You do not have to pre-program the sector, this is done automatically before erasing.

To erase a sector:

Write a Sector Erase Set-up command (20h) to any word address in the sector to be

erased.

Write an Erase Confirm command (D0h) to any word address in the sector to be

erased. If the second command given is not an Erase Confirm, the command aborts

and the ES and PS error flags in the status register are set.

After writing the SE command, reading any address within the bank will return the

Status Register data.

–

While erasure is in progress the PECS bit in the Status Register is ‘0’. When

erasure is completed the PECS bit is ‘1’.

–

The ES bit in the Status Register returns ‘1’ if there has been an erase failure.

–

If the sector is protected, the erase operation aborts and the SP bit in the Status

While the sector erase is ongoing, the bank with the sector being erased accepts only

Read Status Register (70h) and Program/Erase Suspend (B0h) commands.

At the end of the sector erase operation:

–

Write a Clear Status Register (50h) command to the bank to reset the Status

–

The bank will remain in Read Status Register mode until you write a Read Array

(FFh) command.

1.12.2

PG program setup (40h)

The Program command programs a 16-bit array (halfword). Only one bank can be

programmed at a time, the other bank must be in one of the read modes or in program/erase

suspend mode (see Table 6: Rules for dual bank operations).

To program a halfword:

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