Reading/programming the STM32Wxxx embedded Flash memory

PM0073

14/34

Doc ID 17766 Rev 5

2.2.3

Main Flash memory programming

The main Flash memory can be programmed 16 bits at a time. The program operation is

started when the CPU writes a half-word into a main Flash memory address with the PG bit

of the FLASH_CR register set. Any attempt to write data that is not half-word long will result

in a bus error response from the FPEC. If a read/write operation is initiated during

programming (BSY bit set), the CPU stalls until the ongoing main Flash memory

programming is over.

Figure 1.

Programming procedure

Read FLASH_CR_LOCK

FLASH_CR_LOCK

= 1

Yes

No

Yes

No

Perform unlock sequency

Write FLASH_CR_PG to 1

Perform half-word write at the

desired address

FLASH_SR_BSY

= 1

Check the programmed value

by reading the programmed

address

Enable FPEC clock

ai14307c