Hey all,
I'm having trouble with a variable modified in the ISR but not being updated in the main code. A couple comments:
- My variable is volatile
- My ISR is being called (in the code below, if the LED toggling is moved to the ISR it works just fine)
- I don't think I have any other interrupts enabled, so I don't think the whole unit is resetting as I saw suggested in another thread
- I've actually got the code working on an ATmega328p, but "translated" for an ATtiny1616 it doesn't work
Here's the code I'm having trouble with. I've got a button that connects ground to PC1 that triggers the ISR and an LED wired to PC0 that I am trying to toggle by modifying the global volatile x.
#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>
volatile char x;
const uint8_t led_pin = 0; // PORT C
const uint8_t btn_pin = 1; // PORT C
int main() {
// LED setup
PORTC.DIR |= (1 << led_pin); // Set LED pin to output
// Button setup
PORTC.DIR &= ~(1 << btn_pin); // Set button as input
PORTC.PIN1CTRL |= (1 << 3); // Enable pull-up resistor
// Set interrupt on falling edges
PORTC.PIN1CTRL |= (1 << 0);
PORTC.PIN1CTRL |= (1 << 1);
sei(); // Set global interrupts
while(1){
if (x == 1){
PORTC.OUT ^= (1 << led_pin); // toggle led
_delay_ms(500); // debounce
x = 0; // unset x
}
}
}
ISR(PORTC_PORT_vect) {
x = 1; // set x
PORTC.INTFLAGS |= (1 << 1); // Clear interrupt flag
}For comparison, here's my working code for the ATmega328p that does the same thing:
#include <avr/io.h> // for pin and address functions
#include <avr/interrupt.h> // for interrupt related commands
#include <util/delay.h>
volatile char x;
const uint8_t led_pin = PD5; // This is digital pin 5
const uint8_t btn_pin = PD2; // This is the INT0 external interrupt pin
int main() {
// LED setup
DDRD |= (1 << led_pin); // Set LED pin to output
// Button setup
DDRD &= ~(1 << btn_pin); // Set button as input
PORTD |= (1 << btn_pin); // Enable pull-up resistor
// Set INT0 interrupt behaviour: Interrupt on falling edges
EICRA |= (1 << ISC01);
EICRA &= ~(1 << ISC00);
sei(); // Set global interrupts
EIMSK |= (1 << INT0); // Set INT0 interrupts
while(1){
if (x == 1){
PORTD ^= (1 << led_pin); // Set LED pin to high
_delay_ms(500);
x = 0;
}
}
}
ISR(INT0_vect){
x = 1; // set x
}Any ideas guys? I'm using El Tangas' jtag2updi programmer, avr-gcc 8.2.0, and avrdude 6.3. Thanks for taking the time to read this!
Cheers,
S
