8-bit MicrocontrollersのトピックRe: Flash programming (HCS08AW60)

Flash programming (HCS08AW60)

ssinfod — Fri, 28 Mar 2008 11:43:34 GMT

Hi,

I am currently testing a function which writes a byte in the flash memory of the MCU (HCS08AW60).

I would like to know if I have to erase the sector before programming the byte for a second time.

Example :

unsigned char fdata = 0;
unsigned int faddress = 0x870;

fdata = flash_sector_erase(faddress); // Erase page
delay(1000);

fdata = flash_read(faddress);         // read operation (0xFF)
delay(1000);

//1st Write
fdata = 'U';
fdata = flash_write(faddress, fdata); // write operation
delay(1000);

// Read
fdata = flash_read(faddress);         // read operation ( 'U')
delay(1000);

// 2nd Write
fdata = 'A';
fdata = flash_write(faddress, fdata); // write operation
delay(1000);

// Read
fdata = flash_read(faddress);         // read operation ('A')
delay(1000);

It seems I can write the byte at the same address (0x870) a second time without having to erase the sector. Is that true ? Do I have the erase the sector before programming any bytes ?

I also tried it without erasing the sector at all and it works.

Thanks

Re: Flash programming (HCS08AW60)

ssinfod — Fri, 28 Mar 2008 11:46:37 GMT

My flash programming routines are based on example from the forums..

File.c

//==============================================================================
// Write a byte into the specified FLASH address
//==============================================================================
char flash_write(unsigned int address, unsigned char data)
{
unsigned char *pointer;
pointer = (char*) address;
FlashProg(pointer,data); // call the FLASH programming function
if (FSTAT_FACCERR) data=1; else data=0;
if (FSTAT_FPVIOL) data|=2;
return(data);
}

//==============================================================================
// Erase a sector of the FLASH memory
//==============================================================================
unsigned char flash_sector_erase(unsigned int address)
{
unsigned char *pointer, res;
pointer = (char*) address;
FlashErase(pointer);
if (FSTAT_FACCERR) res=1; else res=0;
if (FSTAT_FPVIOL) res|=2;
return(res);
}

File.asm

;*******************************************************************************
;
;*******************************************************************************
FlashErase:
        psha                                                                    ;adjust sp for DoOnStack entry
        lda #(mFPVIOL+mFACCERR)                                                 ;mask
        sta FSTAT                                                               ;abort any command and clear errors
        lda #mPageErase                                                         ;mask pattern for page erase command
        bsr DoOnStack                                                           ;finish command from stack-based sub
        ais #1                                                                  ;deallocate data location from stack
        rts

;*******************************************************************************
;
;*******************************************************************************
FlashProg:
        psha                                                                    ;temporarily save entry data
        lda #(mFPVIOL+mFACCERR)                                                 ;mask
        sta FSTAT                                                               ;abort any command and clear errors
        lda #mByteProg                                                          ;mask pattern for byte prog command
        bsr DoOnStack                                                           ;execute prog code from stack RAM
        ais #1                                                                  ;deallocate data location from stack
        rts

...

Re: Flash programming (HCS08AW60)

peg — Fri, 28 Mar 2008 11:59:00 GMT

Hi ssinfod2,

You have to erase first, or at least start with $FF.
Programming can only change selected 1's to 0's.
Erasing makes all bits at once 1.
You can actually programme a byte twice if you only want to make more of the remaining 1's a 0, but it is strongly discouraged by Freescale.
Sometimes if monitoring with CW it can look like you have programmed a byte when in fact you haven't. Power cycle and check again.

Re: Flash programming (HCS08AW60)

ssinfod — Sun, 30 Mar 2008 12:57:34 GMT

Ok , now I understand better.

Thanks for your answer.

Message Edited by ssinfod2 on 2008-03-30 06:58 AM