Sorry for my ignorance, I haven't used any 18Fxxxx chips yet.

Does the access bit [a] default to 0 (ie bypass the BSR) for any
instructions that do not explicitly set it.

Example:

movwf EECON2 is the same as movwf EECON2,0

Is that a default compiler setting?

cheers

Tony



On Sun, Oct 9, 2016 at 10:19 AM, IVP <joecolquitt@clear.net.nz> wrote:
> Hi all,
>
> I'm having trouble getting a routine to write data where I think it
> should. I've not done any Flash writing for a long time so probably
> missing something pretty obvious. I've checked the d/s and had a
> look around for examples and can't spot anything
>
> The routine receives a packet of 48 bytes and writes it to an address
> defined by the value of a two-digit LED display. For example, if the
> display is showing 09, then the 48 bytes should be written to the block
> starting at (9*64) + 0x1800, where 0x1800 is the base address
>
> What I'm getting though is a write only when display =3D 00 and only
> to the block address in the set-up declaration, eg t_data =3D 0x1800
>
> If I change t_data to 0x1840, it will write there. And explicitly setting
> TBLPTR in the code doesn't make a difference. The blk_add routine
> returns the correct value for TBLPTR, the code seems to ignore it
>
> If 0x1840 is the intended target (dg =3D 1, t_data =3D 0x1800), the write
> will happen only if I clear it with 0000 data statements in the program,
> otherwise the locations will stay as FFFF. But that write does miss the
> first byte. All 48 bytes are correct when dg=3D00
>
> Below is the section of code
>
> Can anyone see what's missing ? I'm sure there's a common cause for
> what's happening
>
> TIA
>
> Joe
>
> ------------------
>
> mov      macro   val,file
>          movlw   val
>          movwf   file
>          endm
>
> t_data =3D 0x1800
>
> ;multiply digits by 64 to find block, add t_data base
> ;
> ;eg
> ;digits =3D 23 in <temp1:temp0> =3D 05c0, + 1800 =3D 1dc0
>
> ;Erase block
> ;Write buffer48 to block
>
> wr_block movff   buffer,postinc0 ;last byte received
>
> ;         movlw   .0              ;display value, manual test
> ;         movwf   dg01
> ;         movlw   .0
> ;         movwf   dg10
>
>          call    blk_add         ;get block start address
>
> ;         clrf    tblptru         ;Flash block address, manual test
> ;         movlw   0x18
> ;         movwf   tblptrh
> ;         movlw   0x40
> ;         movwf   tblptrl
>
> ;Block command can resolve to 8 bytes
> ;Erase command can resolve to 64 bytes (x00,x40,x80,xc0 starts)
>
> ;Erase block
>
> erase    bcf     eecon1,cfgs     ;erase block
>          bsf     eecon1,eepgd
>          bsf     eecon1,wren
>          bsf     eecon1,free
>          bcf     intcon,gie
>          mov     0x55,eecon2
>          mov     0xaa,eecon2
>          bsf     eecon1,wr
>          nop
>          tblrd*-
>
> ;write RAM to Flash as 64-byte (8*8) block
>
>          mov     .8,bitcnth      ;'8-bytes' counter
>          lfsr    fsr1,buffer48   ;data to write
>
> write    mov     .8,bitcntl      ;byte counter
>
> copy8    movff   postinc1,tablat ;copy 8 bytes to write buffer
>          tblwt*+
>          decfsz  bitcntl         ;byte counter
>          bra     copy8
>
>          mov     0x55,eecon2
>          mov     0xaa,eecon2
>          bsf     eecon1,wr
>          nop
>          decfsz  bitcnth         ;8-byte counter
>          bra     write
>          bcf     eecon1,wren
>
>          goto    wait            ;done
>
> ;=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>
> ;Get Flash address from dg10:dg01, tens:units, 00d-30d
>
> blk_add  rlncf   dg10,w          ;combine dg10:dg01
>          rlncf   wreg
>          rlncf   wreg            ;(dg10 * 8) + (dg10 * 2)
>          addwf   dg10,w
>          addwf   dg10,w
>          addwf   dg01,w          ;+ dg01
>          movwf   temp1           ;temp1 =3D (dg10 * 10) + dg01
>          clrf    temp0
>
>          clrc                    ;* 64
>          rrcf    temp1
>          rrcf    temp0
>          rrcf    temp1
>          rrcf    temp0
>
>          clrc                    ;add 0x1800 base address
>          movlw   low(t_data)
>          addwf   temp0
>          movlw   high(t_data)
>          addwfc  temp1
>
>          clrf    tblptru         ;Flash block address
>          movff   temp1,tblptrh
>          movff   temp0,tblptrl
>
>          return
>
>
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