weird pic code problem - Electronic Circuits Projects Diagrams Free

Fletcher · 13th October 2004, 12:59 PM

I cant be bothered commenting it all, but this block of code is meant to 3 print lines of text on a 20x4 hd4470 lcd. the dispmain program clears a counter, sets the cursor position and then calls each routine which prints a line. The 3 line printing routines are exactly the same as each other exept they call a different lookup table and have different labels. The problem i have is when the dispmain program has only the code without the asterisks it works perfectly, however when the other code is entered the pic goes crazy and crashes over and over. can anyone see a problem with it?

Code:

DISPMAIN
CALL CLRDISP
CLRF COUNT1
MOVLW 0X80
CALL CMD
CALL LN1
CLRF COUNT1
MOVLW 0XC0
CALL CMD
CALL LN2
CLRF COUNT1*
MOVLW 0X94*
CALL CMD*
CALL LN4*
RETURN

LN1 MOVF COUNT1,W
CALL SCR1
MOVWF TEMP1
SUBLW 0X26
SKPNZ
GOTO LNEND1
MOVF TEMP1,W
CALL SENDDATA
INCF COUNT1,F
GOTO LN1
LNEND1 RETURN 

LN2 MOVF COUNT1,W
CALL SCR3
MOVWF TEMP1
SUBLW 0X26
SKPNZ
GOTO LNEND2
MOVF TEMP1,W
CALL SENDDATA
INCF COUNT1,F
GOTO LN2
LNEND2 RETURN

LN4 MOVF COUNT1,W
CALL SCR6
MOVWF TEMP1
SUBLW 0X26
SKPNZ
GOTO LNEND4
MOVF TEMP1,W
CALL SENDDATA
INCF COUNT1,F
GOTO LN4
LNEND4 RETURN

SCR1
ADDWF PCL,F
DT "Speed:&"

SCR3
ADDWF PCL,F
DT "Temp: &"

SCR6
ADDWF PCL,F
DT "Mode sets AUTO/MAN&"

JohnBrown · 13th October 2004, 01:15 PM

Quote:

I cant be bothered commenting it all,

Well guess what, I for one, can't be bothered reading it all.
:twisted:

Fletcher · 13th October 2004, 01:31 PM

oh well, screw it. ill rewrite the whole thing and see if if starts working.

**Nigel Goodwin** · 13th October 2004, 01:35 PM

I would suggest your tables may be crossing a 256 byte boundary, this causes the program counter to jump to the wrong location. It's easiest to move all tables to near the beginning of program memory, and jump over them at the start of the program - or you can move them to the start of a 256 byte boundary in higher memory, and set the PCL bits before calling it.

williB · 13th October 2004, 01:40 PM

SKPNZ ..
i've never seen this command .. must be a newer pic..?

Fletcher · 13th October 2004, 01:55 PM

Thanks for the help, i thought it might be something like that. ill have a play with it.

SKPNZ is a pseudo-op ,it gets replaced with BTFSC STATUS,2 when it assembles.

Fletcher · 13th October 2004, 02:09 PM

Yep that fixed it, just had to move the tables higher up.

williB · 13th October 2004, 02:10 PM

Quote:

Originally Posted by Fletcher

Thanks for the help, i thought it might be something like that. ill have a play with it.

SKPNZ is a pseudo-op ,it gets replaced with BTFSC STATUS,2 when it assembles.

oh ..

williB · 13th October 2004, 02:12 PM

Quote:

Originally Posted by Fletcher

Yep that fixed it, just had to move the tables higher up.

how large are the tables..?

**Nigel Goodwin** · 13th October 2004, 02:39 PM

Quote:

Originally Posted by Fletcher

SKPNZ is a pseudo-op ,it gets replaced with BTFSC STATUS,2 when it assembles.

Yes, there's also a large number of others listed in the MPASM helpfile table B.11!.

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13th October 2004, 12:59 PM	(permalink)
Fletcher	weird pic code problem I cant be bothered commenting it all, but this block of code is meant to 3 print lines of text on a 20x4 hd4470 lcd. the dispmain program clears a counter, sets the cursor position and then calls each routine which prints a line. The 3 line printing routines are exactly the same as each other exept they call a different lookup table and have different labels. The problem i have is when the dispmain program has only the code without the asterisks it works perfectly, however when the other code is entered the pic goes crazy and crashes over and over. can anyone see a problem with it? Code: DISPMAIN CALL CLRDISP CLRF COUNT1 MOVLW 0X80 CALL CMD CALL LN1 CLRF COUNT1 MOVLW 0XC0 CALL CMD CALL LN2 CLRF COUNT1* MOVLW 0X94* CALL CMD* CALL LN4* RETURN LN1 MOVF COUNT1,W CALL SCR1 MOVWF TEMP1 SUBLW 0X26 SKPNZ GOTO LNEND1 MOVF TEMP1,W CALL SENDDATA INCF COUNT1,F GOTO LN1 LNEND1 RETURN LN2 MOVF COUNT1,W CALL SCR3 MOVWF TEMP1 SUBLW 0X26 SKPNZ GOTO LNEND2 MOVF TEMP1,W CALL SENDDATA INCF COUNT1,F GOTO LN2 LNEND2 RETURN LN4 MOVF COUNT1,W CALL SCR6 MOVWF TEMP1 SUBLW 0X26 SKPNZ GOTO LNEND4 MOVF TEMP1,W CALL SENDDATA INCF COUNT1,F GOTO LN4 LNEND4 RETURN SCR1 ADDWF PCL,F DT "Speed:&" SCR3 ADDWF PCL,F DT "Temp: &" SCR6 ADDWF PCL,F DT "Mode sets AUTO/MAN&"

13th October 2004, 01:31 PM	(permalink)
Fletcher	oh well, screw it. ill rewrite the whole thing and see if if starts working.

13th October 2004, 01:35 PM	(permalink)
Nigel Goodwin	I would suggest your tables may be crossing a 256 byte boundary, this causes the program counter to jump to the wrong location. It's easiest to move all tables to near the beginning of program memory, and jump over them at the start of the program - or you can move them to the start of a 256 byte boundary in higher memory, and set the PCL bits before calling it. __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

13th October 2004, 01:40 PM	(permalink)
williB	SKPNZ .. i've never seen this command .. must be a newer pic..?

13th October 2004, 01:55 PM	(permalink)
Fletcher	Thanks for the help, i thought it might be something like that. ill have a play with it. SKPNZ is a pseudo-op ,it gets replaced with BTFSC STATUS,2 when it assembles.

13th October 2004, 02:09 PM	(permalink)
Fletcher	Yep that fixed it, just had to move the tables higher up.