Writing Flash Memory

billp — Sat, 08 Jul 2006 00:24:40 GMT

Does anyone have advice on how I can write to the internal flash memory to save data on a MC9S08GB60. I would like to do this from C.

Re: Writing Flash Memory

alex_spotw — Sat, 08 Jul 2006 01:14:24 GMT

Hi:

The Datasheet has a pretty good description of the process to write to the Flash Memory.

If you have Processor Expert, you could check the Internal Flash Bean.

YOu can check the Bootloader application notes, that certainly will have code to write the Flash Memory.

Regards,

Alex

Re: Writing Flash Memory

Ilocano — Mon, 10 Jul 2006 08:36:26 GMT

It is not C but I got this from Freescale. Works for me.

;*********************************************************************
;* FlashErase1 - erases one page of FLASH (512 bytes)
;*
;* On entry... H:X - points at a location in the page to be erased
;*
;* Calling convention:
;* jsr FlashErase1
;*
;* Uses: DoOnStack which uses SpSub
;* Returns: H:X unchanged and A = FSTAT shifted left by 2 bits
;* Z=1 if OK, Z=0 if protect violation or access error
;* uses 32 bytes of stack space + 2 bytes for BSR/JSR used to call it
;*********************************************************************
FlashErase1:
psha ;adjust sp for DoOnStack entry
lda #(FPVIOL+FACCERR) ;mask
sta FSTAT ;abort any command and clear errors
lda #PageErase ;mask pattern for page erase command
bsr DoOnStack ;finish command from stack-based sub
ais #1 ;deallocate data location from stack
rts ;Z = 0 means there was an error

;*********************************************************************
;* FlashProg1 - programs one byte of FLASH
;* This routine waits for the command to complete before returning.
;* assumes location was blank. This routine can be run from FLASH
;*
;* On entry... H:X - points at the FLASH byte to be programmed
;* A holds the data for the location to be programmed
;*
;* Calling convention:
;* jsr FlashProg1
;*
;* Uses: DoOnStack which uses SpSub
;* Returns: H:X unchanged and A = FSTAT shifted left by 2 bits
;* Z=1 if OK, Z=0 if protect violation or access error
;* uses 32 bytes of stack space + 2 bytes for BSR/JSR used to call it
;*********************************************************************
FlashProg1:
psha ;temporarily save entry data
lda #(FPVIOL+FACCERR) ;mask
sta FSTAT ;abort any command and clear errors
lda #ByteProgram ;mask pattern for byte prog command
bsr DoOnStack ;execute prog code from stack RAM
ais #1 ;deallocate data location from stack
rts ;Z = 0 means there was an error

;*********************************************************************
;* DoOnStack - copy SpSub onto stack and call it (see also SpSub)
;* Deallocates the stack space used by SpSub after returning from it.
;* Allows flash prog/erase command to execute out of RAM (on stack)
;* while flash is out of the memory map.
;* This routine can be used for flash byte-program or erase commands
;*
;* Calling Convention:
;* psha ;save data to program (or dummy
;* ; data for an erase command)
;* lda #(mFPVIOL+mFACCERR) ;mask
;* sta FSTAT ;abort any command and clear errors
;* lda #mByteProg ;mask pattern for byte prog command
;* jsr DoOnStack ;execute prog code from stack RAM
;* ais #1 ;deallocate data location from stack
;* ; without disturbing A or CCR
;*
;* or substitute #mPageErase for page erase
;*
;* Uses 29 bytes on stack + 2 bytes for BSR/JSR used to call it
;* returns H:X unchanged and A=0 and Z=1 if no flash errors
;********************************************************************
DoOnStack:
pshx
pshh ;save pointer to flash
psha ;save command on stack
ldhx #SpSubEnd ;point at last byte to move to stack

SpMoveLoop:
lda 0,x ;read from flash
psha ;move onto stack
aix #-1 ;next byte to move
cphx #SpSub-1 ;past end?
bne SpMoveLoop ;loop till whole sub on stack
tsx ;point to sub on stack
tpa ;move CCR to A for testing
and #$08 ;check the I mask
bne I_set ;skip if I already set
sei ;block interrupts while FLASH busy
lda SpSubSize+6,sp ;preload data for command
jsr 0,x ;execute the sub on the stack
cli ;ok to clear I mask now
bra I_cont ;continue to stack de-allocation

I_set:
lda SpSubSize+6,sp ;preload data for command
jsr 0,x ;execute the sub on the stack

I_cont:
ais #SpSubSize+3 ;deallocate sub body + H:X + command
;H:X flash pointer OK from SpSub
lsla ;A=00 & Z=1 unless PVIOL or ACCERR
rts ;to flash where DoOnStack was called

;*********************************************************************
;* SpSub - This variation of SpSub performs all of the steps for
;* programming or erasing flash from RAM. SpSub is copied onto the
;* stack, SP is copied to H:X, and then the copy of SpSub in RAM is
;* called using a JSR 0,X instruction.
;*
;* At the time SpSub is called, the data to be programmed (dummy data
;* for an erase command), is in A and the flash address is on the
;* stack above SpSub. After return, PVIOL and ACCERR flags are in bits
;* 6 and 5 of A. If A is shifted left by one bit after return, it
;* should be zero unless there was a flash error.
;*
;* Uses 24 bytes on stack + 2 bytes if a BSR/JSR calls it
;*********************************************************************
SpSub:
ldhx SpSubSize+4,sp ;get flash address from stack
sta 0,x ;write to flash; latch addr and data
lda SpSubSize+3,sp ;get flash command
sta FCMD ;write the flash command
lda #FCBEF ;mask to initiate command
sta FSTAT ;[pwpp] register command
nop ;[p] want min 4~ from w cycle to r

ChkDone:
lda FSTAT ;[prpp] so FCCF is valid
lsla ;FCCF now in MSB
bpl ChkDone ;loop if FCCF = 0

SpSubEnd:
rts ;back into DoOnStack in flash

SpSubSize: equ (*-SpSub)

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