Reading pins of a pic12f1840

Question

I'm using a pic12f1840 width a pickit3 and mplab x ide (and x8 c compiler). It is probably really easy, but I can't figure out how to read the value of a pin!

void main(void) {

    //setting up TESA
    TRISA = 0b111111;
    TRISA5 = 0; //pin 5 is output
    TRISA1 = 1; //pin 1 in input

    for (;;) {
        RA5 = RA1;
    }
}

This is my code at the moment (I left out the configs and include). I have a led connected to pin 5, and a button (with a pulldown resistor) connected to pin 1. I'm running the whole thing on 3.3 volts.

Answer 1

When dealing with Microchip controllers like the PIC it a real good idea to post a complete code that builds. From my experience the real issue is almost always in the stuff the Original Poster left out.

This code works for me in the simulator:

    /*
     * File:   main.c
     * Author: dan1138
     * Compiler: XC8 v2.20
     * IDE: MPLABX v5.40
     *
     * Created on September 29, 2020, 1:24 PM
     */

    // PIC12F1840 Configuration Bit Settings

    // 'C' source line config statements

    // CONFIG1
    #pragma config FOSC = INTOSC    // Oscillator Selection (INTOSC oscillator: I/O function on CLKIN pin)
    #pragma config WDTE = OFF       // Watchdog Timer Enable (WDT disabled)
    #pragma config PWRTE = OFF      // Power-up Timer Enable (PWRT disabled)
    #pragma config MCLRE = ON       // MCLR Pin Function Select (MCLR/VPP pin function is MCLR)
    #pragma config CP = OFF         // Flash Program Memory Code Protection (Program memory code protection is disabled)
    #pragma config CPD = OFF        // Data Memory Code Protection (Data memory code protection is disabled)
    #pragma config BOREN = OFF      // Brown-out Reset Enable (Brown-out Reset disabled)
    #pragma config CLKOUTEN = OFF   // Clock Out Enable (CLKOUT function is disabled. I/O or oscillator function on the CLKOUT pin)
    #pragma config IESO = ON        // Internal/External Switchover (Internal/External Switchover mode is enabled)
    #pragma config FCMEN = ON       // Fail-Safe Clock Monitor Enable (Fail-Safe Clock Monitor is enabled)

    // CONFIG2
    #pragma config WRT = OFF        // Flash Memory Self-Write Protection (Write protection off)
    #pragma config PLLEN = ON       // PLL Enable (4x PLL enabled)
    #pragma config STVREN = ON      // Stack Overflow/Underflow Reset Enable (Stack Overflow or Underflow will cause a Reset)
    #pragma config BORV = LO        // Brown-out Reset Voltage Selection (Brown-out Reset Voltage (Vbor), low trip point selected.)
    #pragma config LVP = ON         // Low-Voltage Programming Enable (Low-voltage programming enabled)

    // #pragma config statements should precede project file includes.
    // Use project enums instead of #define for ON and OFF.

    #include <xc.h>

    void main(void) {
        //setting up TESA
        TRISA = 0b111111;
        ANSELA = 0; /* make all of PORTA digital I/O */
        TRISAbits.TRISA5 = 0; //pin 5 is output /* use Microchip suggested syntax */
        TRISAbits.TRISA1 = 1; //pin 1 in input  /* use Microchip suggested syntax */

        for (;;) {
            LATAbits.LATA5 = PORTAbits.RA1;  /* use Microchip suggested syntax */
        }
    }

In your case it seems to be two things:

1. Not knowing you need to configure GPIO pins for digital operations.
2. Simple syntax errors.

My example code uses the syntax that's been typically supported by almost all versions of the XC8 compilers for about 10 years now.

The shorter forms you have used may not always available for every controller you could target.