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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Version: 2016.0.7797 / Virus Database: 4656/13173 - Release Date: 10/08/16

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