Internal Memory Configuration and External Expansion - The HCS12/9S12: An Introduction to Software and Hardware Interfacing - page 713

Example 14.5
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Write a function to clear the ACCERR and PVIOL flags in all four blocks in the HCS12
devices with 256 kB of on-chip flash memory.
Solution: The following function clears the ACCERR and PVIOL flags in all four blocks in the
HCS12 devices with 256 kB of on-chip flash memory:
clearflags bclr FCNFG,$03 ; select bank 0

movb #ACCERR 1 PVIOL,FSTAT ; clear the ACCERR and PVIOL flags

bset FCNFG,$01 ; select bank 1

movb #ACCERR 1 PVIOL,FSTAT ; clear the ACCERR and PVIOL flags

bset FCNFG,$03 ; select bank 3

movb #ACCERR 1 PVIOL,FSTAT ; clear the ACCERR and PVIOL flags

bclr FCNFG,$01 ; select bank 2

movb #ACCERR 1 PVIOL,FSTAT ; clear the ACCERR and PVIOL flags

rts

The C language version of the function is as follows:
void clearflags (void)
{

FCNFG & 5 , 0x03; // select bank 0

FSTAT 5 ACCERR 1 PVIOL; // clear the ACCERR and PVIOL flags

FCNFG | 5 0x01; // select bank 1

FSTAT 5 ACCERR 1 PVIOL; // clear the ACCERR and PVIOL flags

FCNFG | 5 0x03; // select bank 3

FSTAT 5 ACCERR+PVIOL; // clear the ACCERR and PVIOL flags

FCNFG & 5 0xFE; // select bank 2

FSTAT 5 ACCERR 1 PVIOL; // clear the ACCERR and PVIOL flags

}

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Example 14.6
▼

Write a function that erases a sector of flash memory. Index register X contains a word-
aligned address within the sector to be erased. Return a 1 in B if the command buffer is not
empty.
Solution: The assembly routine that erases the sector pointed to by index register X is as
follows:
EraseFSector brclr FSTAT,CBEIF,err2ES

; erase prohibited if command buffer not empty

std 0,X ; write any data to sector address

movb #SectorErase,FCMD ; write sector erase command

movb #CBEIF,FSTAT ; launch the erase command

brclr FSTAT,ACCERR+PVIOL,OK2ER ; no error flag?

err2ES ldab #1 ; return error code 1

rts

OK2ER brclr FSTAT,CCIF,OK2ER ; wait until command is completed

ldab #0 ; erase successfully, return code 0

rts