Posted on May 12, 2015 at 08:35Hello
I'm using an STM32F302CB. I use this code to protect the first pages of code which contains a bootloader:
[code]
uint32_t write_protected = FLASH_OB_GetWRP();
uint32_t protect_mask = OB_WRP_AllPages - BOOTLOADER_WP;
/*
Bootloader
pages are not write protected.
*/
if
(write_protected != protect_mask)
{
/*
* Unlock sequence
*/
FLASH_Unlock();
FLASH_OB_Unlock();
/*
* Enable WRP protection fails because factory default of the option flash is 00FF00FF00FFF.
* The function does a check for FFFF and an erase will set it to FFFF too.
* Therefore we do an erase of the option bytes before trying to protect the memory.
* This behavior is OK because no other settings of the option bytes excepts RDP is used.
*/
/*
* Clear flash flags
*/
FLASH_ClearFlag(FLASH_FLAG_EOP | FLASH_FLAG_WRPERR | FLASH_FLAG_PGERR | FLASH_FLAG_BSY);
if
(FLASH_OB_Erase() != FLASH_COMPLETE)
{
/*
* The best error handler we can do here is a reset
*/
NVIC_SystemReset();
}
/*
* Do some NOPs to take care of flash latency
*/
uint16_t loops = 40u;
while
(loops--)
{
__NOP();
}
/*
* Clear flash flags
*/
FLASH_ClearFlag(FLASH_FLAG_EOP | FLASH_FLAG_WRPERR | FLASH_FLAG_PGERR | FLASH_FLAG_BSY);
if
(FLASH_OB_EnableWRP(BOOTLOADER_WP) != FLASH_COMPLETE)
{
/*
* The best error handler we can do here is a reset
*/
NVIC_SystemReset();
}
/*
* Do some NOPs to take care of flash latency
*/
loops = 40u;
while
(loops--)
{
__NOP();
}
/*
* Write Protection OK, lock Flash and do
relaunch
of settings to ensure new settings are used.
*/
FLASH_OB_Lock();
FLASH_Lock();
FLASH_OB_Launch();
}
[/code]
IDE is IAR 7.4. Protecting the Flash pages is working. The Problem is I have some devices which have some Kind of locked Option Bytes. I tried JLinkSTM32.exe which is included in IAR to reset Option Bytes. I tried it manually via jlink. Nothing is working. I'm not able to Change Option Bytes anymore.
RDP is _not_ set to 0xCC. It is set to 0xAA.
Any idea what might be wrong? I have this issue with several Controllers. At the moment I have to unsolder the not working MCUs and replace them with working Versions.
Thanks,
Tilo
