I have a real stumper I've been stuck on for a while. I am programming a PIC16F15376 microcontroller Xpress board in C.
I initialize a volatile variable called buttonIntention to 0. When the interrupt service routine occurs, buttonSet(1) is called, effectively setting buttonIntention = 1. [Note: I have also tried just toggling the buttonIntention variable directly, with no get or set functions.] In main(), the while(1) that is constantly polling checks whether the ISR has gone off (which would set buttonIntention = 1) and if the ISR did, the TESTPIN is set high where I can view it on my o-scope.
I have determined that when I pressed a button, the ISR does indeed fire. buttonIntention is then set to 1 within the ISR, because the commented out code at the end of the ISR I tried works fine.
However, my if(buttonIntention) in my while(1) in main() never actually sees buttonIntention set to 1. I thought having this variable as volatile would fix this issue because it is shared between the ISR and main(), and I thought using a uint8_t type on my 8-bit microcontroller would fix any "atomic" issues I have read about but don't really understand... but, there's still something wrong that the if statement never sees a 1.
Any ideas?
Here is my code:
// CONFIG1
#pragma config FEXTOSC = OFF // External Oscillator mode selection bits->Oscillator not enabled
#pragma config RSTOSC = HFINT32 // Power-up default value for COSC bits->HFINTOSC with OSCFRQ= 32 MHz and CDIV = 1:1
#pragma config CLKOUTEN = OFF // Clock Out Enable bit->CLKOUT function is disabled; i/o or oscillator function on OSC2
#pragma config CSWEN = ON // Clock Switch Enable bit->Writing to NOSC and NDIV is allowed
#pragma config FCMEN = ON // Fail-Safe Clock Monitor Enable bit->FSCM timer enabled
// CONFIG2
#pragma config MCLRE = ON // Master Clear Enable bit->MCLR pin is Master Clear function
#pragma config PWRTE = OFF // Power-up Timer Enable bit->PWRT disabled
#pragma config LPBOREN = OFF // Low-Power BOR enable bit->ULPBOR disabled
#pragma config BOREN = ON // Brown-out reset enable bits->Brown-out Reset Enabled, SBOREN bit is ignored
#pragma config BORV = LO // Brown-out Reset Voltage Selection->Brown-out Reset Voltage (VBOR) set to 1.9V on LF, and 2.45V on F Devices
#pragma config ZCD = ON // Zero-cross detect disable->Zero-cross detect circuit is disabled at POR.
#pragma config PPS1WAY = ON // Peripheral Pin Select one-way control->The PPSLOCK bit can be cleared and set only once in software
#pragma config STVREN = ON // Stack Overflow/Underflow Reset Enable bit->Stack Overflow or Underflow will cause a reset
// CONFIG3
#pragma config WDTCPS = WDTCPS_31 // WDT Period Select bits->Divider ratio 1:65536; software control of WDTPS
#pragma config WDTE = OFF // WDT operating mode->WDT Disabled, SWDTEN is ignored
#pragma config WDTCWS = WDTCWS_7 // WDT Window Select bits->window always open (100%); software control; keyed access not required
#pragma config WDTCCS = SC // WDT input clock selector->Software Control
// CONFIG4
#pragma config WRTC = OFF // UserNVM self-write protection bits->Write protection off
//#pragma config SCANE = available // Scanner Enable bit->Scanner module is available for use
#pragma config LVP = ON // Low Voltage Programming Enable bit->Low Voltage programming enabled. MCLR/Vpp pin function is MCLR.
// CONFIG5
#pragma config CP = OFF // UserNVM Program memory code protection bit->UserNVM code protection disabled
//#pragma config CPD = OFF // DataNVM code protection bit->DataNVM code protection disabled
// ==========================================================================
// Import Header Files
// ==========================================================================
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <xc.h>
#include <math.h>
// ==========================================================================
// Define statements
// ==========================================================================
// Inputs from buttons
#define startButton PORTCbits.RC4
#define profileButton PORTCbits.RC5
#define incrementButton PORTCbits.RC6
#define decrementButton PORTCbits.RC7
#define TESTPIN LATCbits.LATC0
// ==========================================================================
// Global Variables
// ==========================================================================
// ISR Toggle Variables (MUST be declared volatile)
volatile uint8_t buttonIntention = 0;
// ==========================================================================
// General Configuration
// ==========================================================================
// --- --- --- --- --- --- ---
// Configure Inputs and Outputs
// --- --- --- --- --- --- ---
void config_IO(void) {
// --- Set output for 5 gate drivers and LCD rs and en: ---
TRISA = 0; // Set all Port A I/O to output
LATA = 0; // Set all Port A outputs to LOW/0
ANSELA = 0; // Turn Port A analog off (Digital only)
// --- Set output for LCD data: ---
TRISB = 0; // Set all Port B I/O to output
LATB = 0; // Set all Port B outputs to LOW/0
ANSELB = 0; // Turn Port B analog off (Digital only)
// --- Set input from buttons: ---
//TRISC = 0b11111000; // Set Port C 3-7 to input for the buttons
TRISC = 0xF8; // Set Port C 3-7 to input for the buttons
LATC = 0; // Set all Port C outputs LOW
ANSELC = 0; // Turn Port C analog off (Digital only)
}
// --- --- --- --- --- --- ---
// Configure Change Notification for Button Interrupts
// --- --- --- --- --- --- ---
void config_CN(void){
//Clear Interrupt flag
IOCIF = 0;
// Clear all of Port C 0-7 interrupt flags
IOCCF = 0x00;
// Enable interrupts on Positive Edge of the buttons RC3-RC7
IOCCP3 = 1;
IOCCP4 = 1;
IOCCP5 = 1;
IOCCP6 = 1;
IOCCP7 = 1;
IOCIE = 1; //Enable Interrupt
}
// --- --- --- --- --- --- ---
// Configure the oscillator:
// --- --- --- --- --- --- ---
void config_OSC (void) {
// Clear registers
OSCCON1 = 0x00;
OSCCON2 = 0x00;
OSCCON3 = 0x00;
// OSCCON1:
// Use High Freq. Internal Oscillator (HFINTOSC @ 1 - 32 MHz)
//OSCCON1bits.NOSC = 0b110;
OSCCON1bits.NOSC = 0x6;
// OSCFRQ:
// Configure HFINTOSC to 32 MHz
// OSCFRQbits.HFFRQ = 0b110;
OSCFRQbits.HFFRQ = 0x6;
// Divide clock by 1
//OSCCON1bits.NDIV = 0b0000;
OSCCON1bits.NDIV = 0x0;
}
// ==========================================================================
// Button Function
// ==========================================================================
void buttonSet(uint8_t setter){
buttonIntention = setter;
}
uint8_t buttonGet(void){
return buttonIntention;
}
// ==========================================================================
// Interrupt service routine
// ==========================================================================
void __interrupt() isr(void)
{
// If button is pressed...
if(IOCIF == 1 && buttonIntention == 0) {
//buttonIntention = 1; // Change state to indicate that button was somehow pressed intentionally or unintentionally
//OR
buttonSet(1);
IOCIF = 0; //Clear Interrupt flag
}
//if(buttonIntention){
//TESTPIN = 1;
//}
}
// ==========================================================================
// Main function
// ==========================================================================
int main(void) {
WDTCON0bits.SWDTEN = 0x0; // Ensure Watchdog Timer is totally disabled
// Register 10-1 INTCON
INTCONbits.PEIE = 1; // Enable peripheral interrupt
INTCONbits.GIE = 1; // Enable global interrupt
// --- Call configuration functions: ---
config_IO();
config_OSC();
config_CN();
// --- Loop forever: ---
while (1) {
if(buttonGet()){
TESTPIN = 1;
}
}
return 0;
}
I don't know this MCU but allow me two shoots in the dark.
It sounds to me strange that you can turn off the W/D with a simple assignment instruction WDTCON0bits.SWDTEN = 0;. Maybe the watchdog resets your MCU.
In spec of PIC16F15376 I read on page 155:
The IOCIF bit is the logical OR of all the IOCAF-IOCEF flags. Therefore, to clear the IOCIF flag, application firmware must clear all of the lower level IOCAF-IOCEF register bits.
I think a simple IOCIF=0 won't work as expected.