Interrupt on digital pin does not work on Nano RP2040 Connect

Official Hardware Nano Family Nano RP2040 Connect
1

I tried to configure an interrupt on digital input 7 (= GPIO19).
Digital input 7 is configured as INPUT_PULLUP, with a push button I connected digital input 7 several times to GND but the interrupt service routine ( onInterrupt() ) was never called. I tried other pins and other modes (e.g. CHANGE, RISING, FALLING ...).

const int interruptPin = 7;       // Input D7 (= GPIO19)

void setup() {
  Serial.begin(9600);      // initialize serial communication
  pinMode(interruptPin, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(interruptPin), onInterrupt, CHANGE);
  Serial.println("started ");
}

void onInterrupt() {
  Serial.println("onInterrupt  ");
}



void loop() {
  // put your main code here, to run repeatedly:

}
2

I tested on Nano_RP2040_Connect using ArduinoCore-mbed core and attachInterrupt() is working OK as expected.

Be sure to use good enough PULL_UP resistor (4.7K-10K) from the pin to +3.3V

Use this test program with debounce

/*
 * Pin_Interrupt_Test.ino
 * Written by Khoi Hoang (https://github.com/khoih-prog/)
 */

#if !( defined(ARDUINO_NANO_RP2040_CONNECT) && defined(ARDUINO_ARCH_MBED) )
  #error This code is intended to run on ARDUINO_NANO_RP2040_CONNECT uaing the mbed_nano platform! Please check your Tools->Board setting.
#endif

#include <Arduino.h>
#include "pinDefinitions.h"

const int interruptPin = 7;    //7;       // Input D7 (= GPIO19)

volatile bool buttonPressed = false;

void onInterruptRising();

void onInterruptFalling()
{
  if (!buttonPressed && digitalRead(interruptPin) == 0)
  {
    buttonPressed = true;
  }
}

void onInterruptRising()
{
  if (buttonPressed && digitalRead(interruptPin) == 1)
  {
    buttonPressed = false;
  }
}

void heartBeatPrint()
{
  static int num = 1;

  Serial.print(F("H"));        // H means Heartbeat

  if (num == 80)
  {
    Serial.println();
    num = 1;
  }
  else if (num++ % 10 == 0)
  {
    Serial.print(F(" "));
  }
}

void check_status()
{
  static uint32_t checkstatus_timeout  = 0;
  static uint32_t checkbutton_timeout  = 0;

  static uint32_t current_millis;
  
  static bool pressedAck  = false;
  static bool releasedAck = false;
  
#define HEARTBEAT_INTERVAL      5000L

// Debouncing time
#define DEBOUNCE_INTERVAL       100L

  current_millis = millis();

  // Debounce
  if ((current_millis > checkbutton_timeout) || (checkbutton_timeout == 0))
  {  
    if (buttonPressed)
    {      
      digitalWrite(LED_BUILTIN, 1);

      if (!pressedAck)
      {
        Serial.println("\nPin_Interrupt Pressed");
        pressedAck  = true;
        releasedAck = false;
      }

      attachInterrupt(interruptPin, onInterruptRising, RISING);
    }
    else
    {
      digitalWrite(LED_BUILTIN, 0);

      if (!releasedAck)
      {
        Serial.println("\nPin_Interrupt Released");
        releasedAck = true;
        pressedAck  = false;
      }
      
      attachInterrupt(interruptPin, onInterruptFalling, FALLING);
    }
    
    checkbutton_timeout = current_millis + DEBOUNCE_INTERVAL;
  }

  // Print hearbeat every HEARTBEAT_INTERVAL (10) seconds.
  if ((current_millis > checkstatus_timeout) || (checkstatus_timeout == 0))
  {
    heartBeatPrint();
    checkstatus_timeout = current_millis + HEARTBEAT_INTERVAL;
  }
}

void setup()
{
  pinMode(LED_BUILTIN, OUTPUT);

  // Don't need pinMode(). Must use PULL_UP resistor, from 4.7K to 10K from interruptPin to +3.3V 
  //pinMode(interruptPin, INPUT_PULLUP);

  Serial.begin(115200);      // initialize serial communication
  while (!Serial);

  delay(2000);

  Serial.println("\nStart Pin_Interrupt_Test");

  Serial.print("Started interrupt for digitalPinToInterrupt(pin) = "); Serial.println(digitalPinToInterrupt(interruptPin));
  Serial.print("Started interrupt for digitalPinToPinName(pin) = GPIO"); Serial.println(digitalPinToPinName(interruptPin));
  Serial.print("Started interrupt for PinNameToIndex(pin) = D"); Serial.println(PinNameToIndex(digitalPinToPinName(interruptPin)));

  // CHANGE, RISING, FALLING
  attachInterrupt(interruptPin, onInterruptFalling, FALLING);
}

void loop()
{
  check_status();
}

and the debug terminal

Start Pin_Interrupt_Test
Started interrupt for digitalPinToInterrupt(pin) = 7
Started interrupt for digitalPinToPinName(pin) = GPIO19
Started interrupt for PinNameToIndex(pin) = D7

Pin_Interrupt Released
H
Pin_Interrupt Pressed
H
Pin_Interrupt Released

Pin_Interrupt Pressed
HHHHHHHH HHHHHHHHHH HHHHHHHHHH
3

Thanks a lot khoih-prog for the fast response and the Pin_Interrupt_Test.ino, it works perfectly on my Nano_RP2040_Connect.

Why do I have to use an external pull up resistor and can not use the internal one ???

pinMode(interruptPin, INPUT_PULLUP);

1 Like
4

Because there is some unknown bug in Nano_RP2040_Connect core that the INPUT_PULLUP doesn't work as expected. Without the resistor, the voltage is fluctuating like crazy and triggers billions of interrupts per seconds, and crashes the board (orange blinking LED of dead)

5

Thanks a lot.

6

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