Read Protection with bootloader error - Can anyone help?

Posted on May 17, 2011 at 13:18

Hi,

I have a propriatory bootloader which switches between application and bootloader via setting a couple of variables in the backup register ram which does not get erased on a reset.

The problem in question is that when i use the read protection below when the bootloader has loaded a application into the flash starting at 0x8008000 the chip erases the flash (so both bootloader and application) on reset.

When in debug, I can read protect and unprotect the bootloader as expected - the erase only happens when the application is loaded. I have tried doing the read protect at different points (before loading the application, after loading the application and in the application) all to the same conclusion - the flash gets fully erased.

This is my read protect/unprotect code:

void Debug_Read_Protection(FunctionalState u8Enable)

{

u32 u32iDelay;

CommsDebug_TxString(''\n\rP1'');

FLASH_Unlock();

if((FLASH->CR & CR_LOCK_Set) == 0)

{CommsDebug_TxString(''\n\rUnlocked'');}

else{CommsDebug_TxString(''\n\rLocked'');}

FLASH_ReadOutProtection(u8Enable);

FLASH_Lock();

// insert a delay here //

u32iDelay = (u32)70000000;

Debug_Print_FlashRegisters();

do

{u32iDelay--;}

while(u32iDelay!=0);

NVIC_GenerateSystemReset();

}// Debug_Read_Protection() //

void Debug_Print_FlashRegisters(void)

{

CommsDebug_TxString(''\n\rOBR = '');

CommsDebug_TxU32(FLASH->OBR);

CommsDebug_TxString(''\n\rCR = '');

CommsDebug_TxU32(FLASH->CR);

}// Debug_Print_FlashRegisters() //

Can anyone help??

Posted on May 17, 2011 at 13:18

Hi Simon,

You can refer to

http://www.st.com/stonline/products/literature/pm/13259.pdf

for more details regarding Protections, Go the Section 2.4, then subsections 2.4.1 Read protection and 2.4.2 Write protection. You should not remove the Read-out protection when you have your own boot-loader else it will be erased too.

Cheers,

STOne-32.