topic Re: Erasing and writing P-Flash on MC9S12XEP100 fails when running the program normally, but not when stepping with debugger in S12 / MagniV Microcontrollers

Erasing and writing P-Flash on MC9S12XEP100 fails when running the program normally, but not when stepping with debugger

utwig — Wed, 18 Dec 2013 13:50:25 GMT

Hi,

I am trying to erase and write P-Flash with my MC9S12XEP100 application. I am able to successfully step through the subroutines performing the erasure and write. But if I try to run the application normally, an illegal breakpoint stops the program execution.

My P-Flash handling subroutines are derived from the subroutines I use to handle D-Flash in the same application. D-Flash handling works fine. And I have set the FCLKDIV correctly. Below is my code for erasing and writing P-Flash:

void erasePflash(unsigned long sector_address){

unsigned int gpage;

DisableInterrupts;

//Wait for the previous flash command to complete

while(!FSTAT_CCIF);

//Clear ACCERR or FPVIOL if set

if ((FSTAT & 0x30) != 0) {

FSTAT = 0x30;

}

//Erase D-flash command, set global page

gpage = (unsigned int) (sector_address >> 16U);

gpage |= 0x0A00;

FCCOBIX = 0x00;

FCCOB = gpage;

//Address within sector

FCCOBIX = 0x01;

FCCOB = (unsigned int) (sector_address);

//Initiate flash command

FSTAT = FSTAT_CCIF_MASK; //THE APPLICATION CRASHES IF I TRY TO RUN THE PROGRAM NORMALLY PAST THIS LINE

//Wait for the flash command to complete

while(!FSTAT_CCIF);

EnableInterrupts;

}

void writePflashWords(unsigned long address, unsigned int *__far ptr, unsigned char length){

unsigned int gpage;

unsigned int i;

DisableInterrupts;

//Wait for the previous flash command to complete

while(!FSTAT_CCIF);

//Clear ACCERR or FPVIOL if set

if ((FSTAT & 0x30) != 0) {

FSTAT = 0x30;

}

//Data length out of range

if((length < 1) || (length > 4)) {

return;

}

//Program D-flash command, set global page

gpage = (unsigned int) (address >> 16U);

gpage |= 0x0600;

FCCOBIX = 0x00;

FCCOB = gpage;

FCCOBIX = 0x01;

FCCOB = (unsigned int) (address);

//Fill appropriate number of words to FCCOB

for(i=1; i<=length; i++) {

FCCOBIX = i+1;

FCCOB = *ptr;

ptr++;

}

//Initiate flash command

FSTAT = FSTAT_CCIF_MASK; //THE APPLICATION CRASHES IF I TRY TO RUN THE PROGRAM NORMALLY PAST THIS LINE

//Wait for the flash command to complete

while(!FSTAT_CCIF);

EnableInterrupts;

}

Re: Erasing and writing P-Flash on MC9S12XEP100 fails when running the program normally, but not when stepping with debugger

RadekS — Wed, 18 Dec 2013 14:29:50 GMT

Illegal breakpoint here probably means that MCU goes into reset.

I guess that issue could be caused by wrong address format. Please check whether you really use global addresses. See attached memory map.
I would like to also recommend check whether addresses are correctly aligned = global address [2:0] = 0b000
You cannot erase or write the same block from where your code runs. I would like to recommend execute at least critical part (FSTAT = FSTAT_CCIF_MASK; while(!FSTAT_CCIF);) from RAM. See attached example code.
This issue could be simply caused by watchdog (time for flash command is too long). Please check whether you used watchdog and how it is with triggering.

Re: Erasing and writing P-Flash on MC9S12XEP100 fails when running the program normally, but not when stepping with debugger

kef2 — Wed, 18 Dec 2013 15:06:56 GMT

Flash and EEPROM are not readable while being programmed, erased or while any other flash command is executing. When you launch flash command CPU just can't read program code and runaways. Single stepping makes code paused, you continue when erase/program is complete. It is mentioned zilion times in forums that you need to move part of your flash erase/program code to RAM so that flash command is launched (FSTAT = FSTAT_CCIF_MASK;)when program counter points to RAM and not return from RAM while(!FSTAT_CCIF);. Interrupts also have to be disabled while(!FSTAT_CCIF);

Re: Erasing and writing P-Flash on MC9S12XEP100 fails when running the program normally, but not when stepping with debugger

utwig — Thu, 19 Dec 2013 11:19:03 GMT

The problem was related your point 3. Somehow I understood that it is possible to stay executing in P-Flash as long as the application does not try to erase or write the same sector where the execution is happening. But this concerns the whole block, as you said.

Thank you for the good example with the machine code for performing the Flash command while executing from RAM!