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I got to code the typical example of 8 LEDS turning ON and OFF, then all getting ON in a loop.

I got a PIC 18F4550, and coded this:

 List P=18F4550 ;Microcontrolador a utilizar include <P18F4550.inc> ;Definiciones de constantes ;********** Palabra de conficuración ******************************************* CONFIG FOSC = INTOSC_EC ;INTOSC_EC ; Internal oscillator CONFIG PWRT= ON ; Power-up Timer Enable bit CONFIG BOR=OFF ; Brown-out Reset disabled in hardware and software CONFIG WDT=OFF ; WDT disabled CONFIG MCLRE=ON ; MCLR pin enabled CONFIG PBADEN=OFF ; PORTB<4:0> pins are configured as digital I/O CONFIG LVP=OFF ; Single-Supply ICSP disabled CONFIG DEBUG = OFF ; Background debugger disabled CONFIG XINST = OFF ; Extended Instruction disabled ;******************************Variables*********************************** conta equ 0x00 ;********************************************************************************** org 0x0000 movlw 0x62 movwf OSCCON clrf TRISD CICLO bcf PORTD,0 call RETARDO bsf PORTD,0 bcf PORTD,1 CALL RETARDO bcf PORTD,1 call RETARDO bsf PORTD,1 bcf PORTD,2 CALL RETARDO bcf PORTD,2 call RETARDO bsf PORTD,2 bcf PORTD,3 CALL RETARDO bcf PORTD,3 call RETARDO bsf PORTD,3 bcf PORTD,4 CALL RETARDO bcf PORTD,4 call RETARDO bsf PORTD,4 bcf PORTD,5 CALL RETARDO bcf PORTD,5 call RETARDO bsf PORTD,5 bcf PORTD,6 CALL RETARDO bcf PORTD,6 call RETARDO bsf PORTD,6 bcf PORTD,7 CALL RETARDO bcf PORTD,7 call RETARDO bsf PORTD,7 bcf PORTD,0 CALL RETARDO bra CICLO RETARDO movlw .255 movwf conta CICLO2 DECFSZ conta,F bra CICLO2 nop nop nop nop return end

tWhen I simulate, That code is almost working. Sometimes they get turning ON and OFF one after another starting at first led, but sometimes the sequence leaps and some random LEDS get ON unexepectedly.

I tried to add this portion of code before bra CICLO to produce the whole leds ON effect, but it just made it behave the worst.

bcf PORTD,0 bcf PORTD,1 bcf PORTD,2 bcf PORTD,3 bcf PORTD,4 bcf PORTD,5 bcf PORTD,6 CALL RETARDO bsf PORTD,1 bsf PORTD,2 bsf PORTD,3 bsf PORTD,4 bsf PORTD,5 bsf PORTD,6 bsf PORTD,7 CALL RETARDO

This is a picture of my simulation:

enter image description here

What am I doing wrong? How could I make sure, working at 4 MhZ that delays will be 1 second?

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  • \$\begingroup\$ Hello, Diego. I'm a reviewer and I've just rejected the edit you made to Akintoyeii's answer. It's nothing personal, it's just that the correct way to report what fixed your problem is for you to post your own answer (yes, you can answer your own question, if that makes sense) or you can post a comment to his answer complementing what else you had to do to solve your problem. Then, if he chooses to do so, he can edit his own answer. \$\endgroup\$ Commented Jun 9, 2014 at 1:29

1 Answer 1

Reset to default
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Try writing to the respective LATDx registers use only PORTD for read operations

 bcf LATD,0

This should fix your problem

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    \$\begingroup\$ @diegoaguilar I had to reject your edit as "too radical", even though the information is useful. In a situation like this, it's better to post it as a comment, rater than an edit. \$\endgroup\$ Commented Jun 9, 2014 at 1:59
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    \$\begingroup\$ Code, which was proposed in Diego's edit, is bcf LATD,x and bsf LATD,x \$\endgroup\$ Commented Jun 9, 2014 at 2:00

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