Can't get interrupts to work

[gizmo71]

Using the Arduino IDE 1.8.15, arduino-pico 1.9.3 as the board, on a Raspberry Pi Pico (bought this week!). My first sketch, which uses a toggle switch with each side connect to digital pins 14 and 15 (physically 19 and 20) and a potentiometer attached to ADC 0 (physical pin 31). The first version used simple polling to read the input values, which it writes out via the serial port, but I thought I would try and get the two digital inputs to use interrupts instead, with no success.

const uint POT_PIN = A0;
const uint SWITCH1_PIN = D14;
const uint SWITCH2_PIN = D15;

volatile int s1, s2, pot;

#define USE_INTERRUPTS 0

#if USE_INTERRUPTS
void switch1() {
  s1 = digitalRead(SWITCH1_PIN) == LOW;
}

void switch2() {
  s2 = digitalRead(SWITCH2_PIN) == LOW;
}
#endif

void setup() {
  pinMode(SWITCH1_PIN, INPUT_PULLUP);
  pinMode(SWITCH2_PIN, INPUT_PULLUP);
#if USE_INTERRUPTS
  switch1();
  attachInterrupt(digitalPinToInterrupt(SWITCH1_PIN), switch1, CHANGE);
  switch2();
  attachInterrupt(digitalPinToInterrupt(SWITCH2_PIN), switch2, CHANGE);
#endif
}

void loop() {
  pot = analogRead(POT_PIN);
#if !USE_INTERRUPTS
  s1 = digitalRead(SWITCH1_PIN) == LOW;
  s2 = digitalRead(SWITCH2_PIN) == LOW;
#endif
  sleep_ms(5);
}

void setup1() {
  Serial.begin(115200);
}

void loop1() {
  sleep_ms(500);
  Serial.print(pot);
  Serial.print(", ");
  Serial.print(s1);
  Serial.print("/");
  Serial.println(s2);
}

(There's no fundamental reason why the serial stuff is in the second core. I've tried doing everything in the first core, with no change in outcome.)

With USE_INTERRUPTS set to 0, it all works swimmingly. But with it set to 1, s1/s2 never get set; the potentiometer still gets read, as you would expect.

Looking at #25/#26, I would expect interrupts to work; I'm probably doing something really stupid, but can't for the life of me see what.

Any ideas?

[grandaspanna]

I've definitely had interrupts working, both with the Arduino attachInterrupt() and the native gpio_set_irq_enabled_with_callback(). I settled on the latter so I could have one interrupt handler that worked out which pin triggered the interrupt.

However, that doesn't explain your issue. Can't see an obvious problem, but in my code, I simply use the GPIO number in the digitalPinToInterrupt macro. Otherwise, I'd start by putting some LED toggling in the interrupt handler, to avoid any issues with variables. That way, you can see if the interrupt is getting called at all.

Having said all of that, I tried your code on my Pico and it works (core: 1.9.1)

[grandaspanna]

It's odd, because your code works for me, so it's possibly something in your environment. I do have a slightly older release, maybe something broke recently?

[gizmo71]

The gpio_set_irq_enabled_with_callback call works so there's obviously something borked somewhere in the Arduino wrapper; thanks for your help.

[grandaspanna]

Good news/bad news. I updated to 1.9.3 and it breaks. It works in 1.9.2 though

[earlephilhower]

Can you help pinpoint the change in 1.9.3 that caused the issue?

If you could go to 1.9.3 and edit platform.txt and change

compiler.libstdcpp="{runtime.platform.path}/lib/libstdc++.a"

to

compiler.libstdcpp="-lstdc++"

and re-try? I have a suspicion that something in the ARM binary support got busted when disabling C++ exceptions, and the above change will use the standard library instead of the no-exceptions version.

[gizmo71]

I have a suspicion that something in the ARM binary support got busted when disabling C++ exceptions, and the above change will use the standard library instead of the no-exceptions version.

Bingo! That edit got it working with 1.9.3. 🥇