RP2040 Deep Sleep and Wake up using external interrupt

Hardware Nano Family Nano RP2040 Connect
1

Hi.
Arduino Newbie here. This is my very first Arduino project and I’m stuck with a basic thing.

I want to put my rp2040 to deep sleep mode and wake it up using an external interrupt using a GPIO pin.
My query is in 2 parts.

  1. Can we use the same pin to receive a signal and be used as an interrupt pin?
    (For example, pin 2 receives a signal from photodiode capturing light, and then this pin sends interrupt to wake the mcu up. )

  2. Does _wfi() function actually put the mcu to sleep?

I used this code and I see no difference in the behaviour. The functionality in loop() still executes.


#include <Arduino.h>

// Define the pin connected to the photodiode
const int photodiodePin = 2;

// Interrupt Service Routine (ISR)
void handleInterrupt() {
  // This function will be called when the interrupt occurs
  // Wake up the device
}

void setup() {
  // Initialize serial communication for debugging
  Serial.begin(115200);
  delay(1000); // Wait for serial to be ready

  // Initialize the photodiode pin as an input
  pinMode(photodiodePin, INPUT);

  // Attach interrupt to the photodiode pin
  // This will call the handleInterrupt function when a rising edge is detected
  attachInterrupt(digitalPinToInterrupt(photodiodePin), handleInterrupt, RISING);

  Serial.println("Setup complete. Going to sleep...");
}

void loop() {

  // Go to sleep using WFI (Wait For Interrupt)
  __wfi();

  // Code here will run after the device wakes up
  Serial.println("Woke up!");
  delay(1000); // Add a delay to avoid rapid prints
}

While doing some googling, I found out that since it is an pi based mcu, I’d need pico sdk to achieve this behaviour. But I’m kinda lost here. That is much complicated for me.

I would appreciate if experts here can point me to any potential solutions/ resources I can follow.
Also, please be kind if my explanation wasn’t so good. I just started learning arduino so I have a very limited technical vocabulary regarding arduino. :slight_smile:

Thanks in advance for any help.

2

I don't see any call to a sleep function. Find a working sample and modify it for your use case.