AT32F421
Series Reference Manual
2022.11.11
Page 33
Rev 2.02
1.2 List of abbreviations for registers
Table 1-4
List of abbreviations for registers
Register type
Description
rw
Software can read and write to this bit.
ro
Software can only read this bit.
wo
Software can only write to the bit. Reading it returns its reset value.
rrc
Software can read this bit. Reading this bit automatically clears it.
rw0c
Software can read this bit and clear it by writing 0. Writing 1 has no effect on this bit.
rw1c
Software can read this bit and clear it by writing 1. Writing 0 has no effect on this bit.
rw1s
Software can read this bit and set it by writing 1. Writing 0 has no effect on this bit.
tog
Software can read this bit and toggle it by writing 1. Writing 0 has no effect on this bit.
rwt
Software can read this bit. Writing any value will trigger an event.
resd
Reserved.
1.3 Device characteristics information
Table 1-5
List of abbreviations for registers
Register abbr.
Base address
Reset value
F_SIZE
0x1FFF F7E0
0xXXXX
UID[31: 0]
0x1FFF F7E8
0xXXXX XXXX
UID[63: 32]
0x1FFF F7EC
0xXXXX XXXX
UID[95: 64]
0x1FFF F7F0
0xXXXX XXXX
1.3.1
Flash memory size register
This register contains the information about Flash memory size.
Bit
Abbr.
Reset value
Type
Description
Bit 15: 0 F_SIZE
0xXXXX
ro
Flash size, in terms of KByte
For example: 0x0040 = 64 KByte
1.3.2
Device electronic signature
The device electronic signature contains the memory size and the unique device ID (96 bits). It is stored
in the information block of the Flash memory. The 96-bit ID is unique for any device, and cannot be
altered by users. It can be used for the following purposes:
Serial number: such as USB string serial number
Part of security keys
Bit
Abbr.
Reset value
Type
Description
Bit 31: 0 UID[31: 0]
0xXXXX XXXX
ro
UID for bit 31 to bit 0
Bit
Abbr.
Reset value
Type
Description
Bit 31: 0 UID[63: 32]
0xXXXX XXXX
ro
UID for bit 63 to bit 32