AT32F421
Series Reference Manual
2022.11.11
Page 65
Rev 2.02
Figure 5-3
Flash memory programming process
OBF = 0?
Set the FPRGM bit = 1 in
FLASH_CTRL
Write word/half-word/byte
(32bits/16 bits/8bits) data
No
Yes
Start
Check the OBF bit in
FLASH_STS
No
Check the OBF bit in
FLASH_STS
OBF = 0?
Yes
Read EPPERR bit
、
PRGMERR
bit and ODF bit in FLASH_STS
End
5.2.4
Read operation
Flash memory can be accessed through AHB bus of the CPU.
5.3 Main Flash memory extension area
Boot memory can also be programmed as the extension area of the main Flash memory to store user-
application code. When used as main Flash memory extension area, it behaves like the main Flash
memory, including read, unlock, erase and programming operations.