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4th bit of PIC16F84 PORTA no working electrically

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I'm using SimulIDE-0.4.15-SR10.appimage in ubuntu 18.
I have assembled the code bellow using gpasm 1.4.0.
      list      P=PIC16F84, R=D
      include   "p16f84.inc"

temp1      equ      0Ch
temp2      equ      0Dh
count      equ      0Eh

      org      0000h   
      goto      start

      org      0008h

start      bsf      STATUS,RP0

      movlw      b'00000'
      movwf      TRISA
      movlw      b'11111111'
      movwf      TRISB

      bcf      STATUS,RP0   

main      movf      PORTB   ,W
      movwf      PORTA   
      goto   main

The code was successfully assembled.
It's supposed to copy the content from inputs in pins B0 to B4 from PORTB and copy to outputs in pins A0 to A4 from PORTA.

The MCU Monitor shows that the code is executing okay.
The TRISA and TRISB is correctly configured (setting every pin in PORTA as output and every pin in PORTB as input).
The value recorded in register PORTB corresponds to the electrical levels driven to the pins and is correctly copied to PORTA.
Thus, I'm able to change the value of the A4 bit in PORTA register by changing B4.

Nevertheless, A4 electrical voltage keep stuck in 0V, no matter the value in the register PORTA.




I think PORTA4 is open drain, so you need a pull up resistor.


arcachofo wrote:Hi.

I think PORTA4 is open drain, so you need a pull up resistor.

You're correct. It worked with a pull-up. So, it's not a bug.



Glad to know that you could solve it.

Anyway thanks for reporting.

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