Program Working on Old Device and New Device's Simulator but not on New Device

Question

I'm hitting a roadblock in porting over a program I previously wrote for the PIC10F200 (see this related SO question). Turns out another component on the board needed to be swapped out for something that needed to be communicated with through I2C, so ergo, I'm porting the program to the PIC12LF1552.

This is how the program currently works (at least on the PIC10F200)

Program starts at IDLE (no lights on)
Press the button, the T0CKI pin (in the PIC12LF1552's case, RA2) is already pulled up to VDD (~3.3V) by an external pull-up resistor, the button is connected to ground and the pin, ergo pulling T0CKI's signal to LO.
TMR0 increments (supposedly)
After a time period where PORTAbits.RA2 settles, state increments
switch block moves to turn the external LED on, in the previous version of the circuit, this would also activate the IC this pin is connected to.
Rinse repeat for the other 3 states.

I have re-verified this functionality through using MPLAB X's simulator where I fired T0CKI (again, configured as RA2, again confirmed by the simulator) to HI and then to LO to engage the TMR0 code. state increments, and everybody is happy.

When I program the device using either MPLAB X connected to my PICkit3 or the included standalone programmer MPLAB IPE, the program does not work as intended. I have re-verified all connections, the programming port is connected as it should be. The button is attached the right pin. The test LED is attached to the right pin. For the time being we are not considering any I2C communication, I just want to see my status LED (RA4) toggle.

I know that now that I've transitioned to a midrange PIC, I can use the interrupt features, but for the time being I want to get what I know has worked on a much simpler device working on the current one.

My question then is, why doesn't this program work when programmed to the PIC12LF1552, but yet works on the PIC12LF1552 simulator AND its previous incarnation worked on the PIC10F200 (both programmed and simulated)?

Thanks in advance everyone!

The following is the entire program:

#if defined(__XC)
    #include <xc.h>         /* XC8 General Include File */
#endif

#include <stdint.h>        /* For uint8_t definition */
#include <stdbool.h>       /* For true/false definition */
#include <stdio.h>
#include <stdlib.h>

/******************************************************************************/
/* Defines                                                                    */
/******************************************************************************/

//#define SYS_FREQ        16000000L
//#define FCY             SYS_FREQ/4
#define _XTAL_FREQ      500000

__CONFIG
(
    MCLRE_ON &
    CP_OFF &
    BOREN_OFF &
    WDTE_OFF &
    PWRTE_OFF &
    FOSC_INTOSC
);

void main(void)
{
    TRISA = 0b101111;
    OPTION_REG = 0b01111111;
    APFCONbits.SDSEL = 1;

    unsigned char state = 0;
    unsigned char count = 0;

    while(1)
    {
        switch (state)
        {
            case 0: // IDLE/OFF
                if (LATAbits.LATA4) LATAbits.LATA4 = 0;
                break;
            case 1: // ON
                if (!LATAbits.LATA4) LATAbits.LATA4 = 1;
                break;
            case 2: // BLINK (slow)
                LATAbits.LATA4 = !LATAbits.LATA4;
                __delay_ms(100);
                break;
            case 3: // BLINK (fast)
                LATAbits.LATA4 = !LATAbits.LATA4;
                __delay_ms(50);
                break;
            case 4: // BEAT DETECT
                LATAbits.LATA4 = LATAbits.LATA5;
                break;
            default:
                state = 0;
                break;
        }      

        if (TMR0 > 0)
        {
            while (count < 20)
            {
                if (!PORTAbits.RA2) count = 0;
                __delay_ms(10);
                count++;
            }
            TMR0 = 0;
            state++;
        }
    }
}

Ruslan Gerasimov Ruslan Gerasimov · Accepted Answer · 2014-07-17T04:49:02

Some of the pins may be configured as Analog Inputs.

From the Datasheet for this device

"The operation of pin RA4 as analog is selected by setting the ANS3 bit in the ANSEL register which is the default set-ting after a Power-on Reset".

If you do not set the ANSEL register the pin cannot be used as output as it is configured as an analog input.

This applies to all the pins that can be A/D inputs.

I do not see any configuration bit setup in your code.

Setting ANSEL and ANSELH to 0 should do the trick.

According to the this documentation , on page 93 about the ANSELA register

"The ANSELA bits default to the Analog mode after Reset. To use any pins as digital general purpose or peripheral inputs, the corresponding ANSEL bits must be initialized to ‘0’ by user software."

If you don't plan to use analog inputs, you may add something like ANSELA=0;

Program Working on Old Device and New Device's Simulator but not on New Device

1 Answers