I have have the following program and one LED connected to every port pin. All pins are outputs. The problem is that LEDs connected to RA4/TOKI and RB4,5,6,7 don't blink. During the simulation everything seems to work. I have MPLAB V3,40.

In fact this is a test program for 16F84 and i am using 220Ω resistors to interface the LEDs.

As Matt said "RA4 is an open drain output only- it has no way of sourcing current. If you want to use it to drive an LED- you have to attach one end of the LED (through a resistor) to +5 and connect the other end to RA4. Setting RA4 will turn LED off, clearing RA4 will turn the LED on." I tried it and it didn't work. I also tried to drive a 4 to 16 decoder (less current consumption) and that didn't work either.

As far as RB4,5,6,7 are concerned they still don't work.

I had some replies but only Matt helped me. I dont want you to send me delay routines. I want to find out whats wrong and it doesn't work. Maybe there is a mistake in the program (it is working during simulation) or i haven't configured a register corectly or even not at all. I have to say that i dont know much about PICs but i am trying.

I thank you in advance AHILLEAS.

list p=16f84
#include "p16f84.inc"

porta equ 05
portb equ 06
status equ 03
trisa equ 85
trisb equ 86

del equ 20
del1 equ 21

     org 0
start
     clrf porta
     clrf portb
     bsf status,5
     clrf trisa
     clrf trisb
     bcf status,5

start1
     incf porta
     incf portb
     movlw h'ff'
     movwf del1

delay1
     movlw h'ff'
     movwf del
delay
     decfsz del
     goto delay
     decfsz del1
     goto delay1

     goto start1

     end