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GD32E23x User Manual
51
Read and verify the flash memory if required using a DBUS access.
When the operation is executed successfully, an interrupt will be triggered by FMC if the
ENDIE bit in the FMC_CTL register is set, and the ENDF in FMC_STAT register is set. Note
that before the word/half word programming operation you should check the address that it
has been erased. If the address has not been erased, PGERR bit will set when programming
the address include programming 0x0. The end of this operation is indicated by the ENDF bit
in the FMC_STAT register.
2.3.10.
Option byte description
The option bytes block of flash memory reloaded to FMC_OBSTAT and FMC_WP registers
after each system reset or OBRLD bit set in FMC_CTL register, and the option bytes work.
The option complement bytes are the opposite of option bytes. When option bytes reload, if
the option complement bytes and option bytes does not match, the OBERR bit in
FMC_OBSTAT register is set, and the option byte is set to 0xFF. The
is the detail of option bytes.
Table 2-3. Option byte
Address
Name
Description
0x1fff f800
OB_SPC
option byte Security Protection Code
0xA5: No protection
any value except 0xA5 or 0xCC: Protection level low
0xCC: Protection level high
0x1fff f801
OB_SPC_N
OB_SPC complement value
0x1fff f802
OB_USER
option byte which user defined
[7]: Reserved
[6]: SRAM_PARITY_CHECK
0: Enable SRAM parity check
1: Disable SRAM parity check
[5]: VDDA_VISOR
0: Disable V
DDA
monitor
1: Enable V
DDA
monitor
[4]: BOOT1_n
0: BOOT1 bit is 1
1: BOOT1 bit is 0
[3]: Reserved
[2]: nRST_STDBY
0: Generate a reset instead of entering standby mode
1: No reset when entering standby mode
[1]: nRST_DPSLP
0: Generate a reset instead of entering Deep-sleep mode
1: No reset when entering Deep-sleep mode
[0]: nWDG_SW
0: Hardware free watchdog timer