GPR problem with 16f877

[kvrajasekar]

Hi,

I am using 16f877(asm code).my project required 150 registers to store some data.I have used bank0,1,2 to declare registers.But when i used bank0 and bank1 simultaneously my loop is getting hang.

Please help me...here is my code..

copy_limits routine is there in page 2.to access it i used fcall.but when the control enters into copy_thu..it gets hanging.

 

[Diver300]

There is a lot of code missing in what you posted. We can't guess what

		goto	copy_sun

does when there is no "copy_sun" marker.

As a start, you are using a lot of bankselects that aren't needed.

	cblock		0xa0

st_thu_min1
st_thu_hr1

.........

clear_thu
		banksel	st_thu_min1
		clrf	st_thu_min1
		banksel	st_thu_hr1
		clrf	st_thu_hr1

You don't need to select banks when you are already in that bank.

You are using the wrong tool for the job. The 16F877 is a pain for stuff like that. There is no good way to transfer a block of data, as there is only one indirect addressing register.

If you use a PIC18F4420, you can access 196 registers directly, without having to change banks. It is just about pin compatible with the 16F877

If you want to transfer a block of data, you can write:-

	lfsr	fsr0, source
	lfsr	fsr1, destination
	movlw	data_size
	movwf	count
transfer_loop
	movff	postinc0, postinc1
	decfsz	count, f
	bra		transfer_loop

 

[Mike - K8LH]

You are using the wrong tool for the job. The 16F877 is a pain for stuff like that. There is no good way to transfer a block of data, as there is only one indirect addressing register.

If you use a PIC18F4420, you can access 196 registers directly, without having to change banks. It is just about pin compatible with the 16F877

If you want to transfer a block of data, you can write:-

         lfsr    fsr0, source
         lfsr    fsr1, destination
         movlw   data_size
         movwf   count
transfer_loop
         movff   postinc0, postinc1
         decfsz  count, f
         bra     transfer_loop

It's only slightly more difficult to copy blocks of memory on the 16F' devices. Here's a method I use from PICLIST;

        movlw   d'16'           ; record byte count               |B0
Data_Copy
        movwf   Count           ; save count                      |B0
        addlw   Source-1        ; source buffer address           |B0
        movwf   FSR             ; setup source indirect           |B0
        movf    INDF,W          ; get data byte                   |B0
        movwf   Temp            ; save it                         |B0
        movlw   Target-Source   ; add buffer span                 |B0
        addwf   FSR,F           ; setup target indirect           |B0
        movf    Temp,W          ; retrieve data                   |B0
        movwf   INDF            ; copy into DBLOCK                |B0
        decfsz  Count,W         ; all bytes copied?               |B0
        goto    Data_Copy       ; no, branch, else                |B0

The OP's choice of device family is not the problem. It's his program organization.

Mike

 

[kvrajasekar]

Thanks for all...I solved the problem...now my project is workin fine.