Need help - need to flash a LED on PortA

Hi, this is driving me insane. I am unable to figure out why my code (below) to blink a LED on PortA does not work. The test circuit is fine. Everything compiles and burns onto the 628A PIC chip. But it does not do jack.

Could someone please help me out here.

Thank you, zalzon

------ ;portsend.asm to show to flash a led on porta, ra0.

;************************************* setup

list p = 16F628A ;processor type org 0020h

STATUS equ h'3' CMCON equ h'1F' TRISA equ h'85' RP1 equ h'6' RP0 equ h'5' PORTA equ h'05' reg1 equ h'20'

;************************************* program

goto Start

Start MOVLW 0x07 ;disable the comparators MOVWF CMCON

bsf STATUS, RP0 ;switch to bank 1 bcf STATUS, RP1

movlw b'00000000' ;all IO pins = outputs movwf TRISA

bcf STATUS, RP0 ;switch back to bank 0 bcf STATUS, RP1

movlw b'00000000' ; all port pins = low movwf PORTA goto Test

Test movlw d'255' ;counter to delay for a few milliseconds movwf reg1 BSF PORTA,0 ;set porta, bit 0 on goto Decrement1 ;begin delay Back1 BCF PORTA,0 ;set porta, bit 0 off movlw d'255' movwf reg1 goto Decrement2 Back2 goto Test

Decrement1 nop nop nop decfsz reg1, 1 goto Decrement1 goto Back1

Decrement2 nop nop nop decfsz reg1, 1 goto Decrement2 goto Back2

Finished end

Reply to
zalzon
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You need to set an org for the code memory. Try using CBLOCK rather than org for the file registers, if you want to write your program in absolute.

Best regards, Spehro Pefhany

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Reply to
Spehro Pefhany

Hi, pic code starts at org0 not 20. You can find some templates on the microchip site. Some chips have adconverters on porta, they come up as analoge from reset.

Reply to
CBarn24050

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