topic Re: Writing to Flash with LAP on S08DZ128 in 8-bit Microcontrollers

Writing to Flash with LAP on S08DZ128

lc_hc — Tue, 03 Aug 2010 04:15:49 GMT

HI there,

I´m writing a Flashdriver to be able to write data to the flash memory from a bootloader application. I read a lot about that and searched though the forum but unfortunately didn´t gest the desired results. So my question is, if I can read / write to the complete flash memory by using the LAP register ? The documentation says yes, but it seems to be inconsitent sometimes.

What about the PPAGE method ? Are there pro´s and con´s between both methods ? Anyway, I placed my code below, so maybe anyone can help me. Thank you very much in advance for helping !

void RAM_Routine( tUI16 Address, tUI8 Value, tUI8 Command )
{

    /* clear FACCERR flag */
    FSTAT |= FSTAT_FACCERR_MASK_UI8;

#ifdef MMU_USAGE == LAP_ADDRESSING

    /* set LAP ( Linear Address Pointer ) to desired location */
   LAP0 = 0xFF & Address;
    LAP1 = 0XFF & ( Address << 8 );
    LAP2 = 0xFF & ( Address << 16 );

    /*
   _asm("PSHA");
   _asm("LDA @Address:LINEAR_HIGH");
   _asm("STA LAP2");
   _asm("LDA @Address:LINEAR_MID");
   _asm("STA LAP1");
   _asm("LDA @Address:LINEAR_LOW");
   _asm("STA LAP0");
   _asm("PULA");
   */
   /* increment LAP register value / step to next byte in the flash */
   LB = Value;

#elif MMU_USAGE == PAGED
   /* TODO incrementing of data pointer */

   /* step to next byte in the flash */
#else

    /* write data to the block to erase */
    *(tUI8*)Address = Value;
#endif /*MMU_USAGE*/

   /* load command */
   FCMD |= Command;

   /* set FCBEF to start the command */
   FSTAT |= FSTAT_FCBEF_MASK_UI8;

   /* wait for four cycles before checking FSTAT register */
   (void)FCDIV;

   /*was the operation succesful?*/
   if( !( FSTAT & FSTAT_ERROR_MASK_UI8 ) )
   {
      /*wait for FCCF flag*/
      while( !( FSTAT & FSTAT_FCCF_MASK_UI8 ) )
      {
          /*change this to the system used function to reset the watchdog*/
          SERVICE_WATCHDOG();
      }
   }

return;
}

/*** end of RAM_Routine() ***/

Re: Writing to Flash with LAP on S08DZ128

tonyp — Tue, 03 Aug 2010 13:45:17 GMT

Yes, it's possible to use LAP, although I have been doing it with pages until now.

I didn't have a thorough look at your code, just one obvious mistake that caught my eye. Shouldn't you be right shifting?

    /* set LAP ( Linear Address Pointer ) to desired location */
   LAP0 = 0xFF & Address;
    LAP1 = 0XFF & ( Address << 8 );
    LAP2 = 0xFF & ( Address << 16 );

Re: Writing to Flash with LAP on S08DZ128

kef — Tue, 03 Aug 2010 15:19:33 GMT

/* clear FACCERR flag */
FSTAT |= FSTAT_FACCERR_MASK_UI8;

Above is wrong. Oring FSTAT with anything will write '1' to FCBEF bit if FCBEF is already set. Effectively it is attempt to launch flash command. Since flash erase/write sequence is most likely violated, error flag will be reset back to '1'...

For DZ128 Address should be wider than 16 bits integer.

Re: Writing to Flash with LAP on S08DZ128

lc_hc — Tue, 03 Aug 2010 16:50:14 GMT

Hi,

thank you for helping. Ok so I was wrong with shifting, that shouldn´t happen. Do you agree with my code fundamentally ?

I mean should the code work regarding your suggested changes ?

I feel it´s pretty hard to get into this stuff when you never did flash programming routines before

Thank you guys,

Best regards,

Simon

Re: Writing to Flash with LAP on S08DZ128

AndersJ — Fri, 23 Dec 2011 20:52:59 GMT

DZ128.

What is the best and correct way to set up a 24 bit

pointer to a flash array in adress 0x48000,

and then write a byte to the adress to start a sector erase.

Thanks,

Anders