Pin interrupts on Rpi pico with arduno-pico code

Projects Programming
1

I'm using the Arduino IDE with the arduino-pico core and I'm trying to get pin interrupts working for a rotary encoder application. Here is the code:

#define ROTA       6    // GPIO6    rotary encoder A
#define ROTB       7    // GPIO7    rotary encoder B

// rotary encoder pin change interrupt handler
void readEncoder() {
  encoder_state = (encoder_state << 4) | (digitalRead(ROTB) << 1) | digitalRead(ROTA);

  Serial2.println(encoder_state);

  switch (encoder_state) {
    case 0x23:  encoder_val++; break;
    case 0x32:  encoder_val--; break;
    default: break;
  }
}

// rotary encoder init
void encoder_init() {
  attachInterrupt(ROTA, readEncoder, RISING);
  attachInterrupt(ROTB, readEncoder, RISING);
  encoder_state = (digitalRead(ROTB) << 1) | digitalRead(ROTA);
  interrupts();
}

The print statement never executes when I turn the encoder.

2

Hi
There is neither setup nor loop in this code... Please show your full sketch.

3 
// ============================================================================
//  encoder ::  rotary ecoder interrupt test
//
//  Arduino IDE settings:
//  board: Raspberry Pi Pico (Arduino-Pico)
//  programmer: none
//
// ============================================================================

#define TXD1       8    // GPIO8   PIN11  UART1 Tx
#define RXD1       9    // GPIO9   PIN12  UART1 Rx
#define ROTA       6    // GPIO6   PIN8   rotary encoder A
#define ROTB       7    // GPIO7   PIN9   rotary encoder B

int8_t  encoder_val = 0;
uint8_t encoder_state;

// rotary encoder pin change interrupt handler
void readEncoder() {
  encoder_state = (encoder_state << 4) | (digitalRead(ROTB) << 1) | digitalRead(ROTA);
  Serial2.println(encoder_state);
  switch (encoder_state) {
    case 0x23:  encoder_val++; break;
    case 0x32:  encoder_val--; break;
    default: break;
  }
}

// rotary encoder init
void encoder_init() {
  // enable pin change interrupts
  attachInterrupt(digitalPinToInterrupt(ROTA), readEncoder, RISING);
  attachInterrupt(digitalPinToInterrupt(ROTB), readEncoder, RISING);
  encoder_state = (digitalRead(ROTB) << 1) | digitalRead(ROTA);
  interrupts();
}

// startup initialization
void setup() {
  pinMode(ROTA, INPUT_PULLUP);
  pinMode(ROTB, INPUT_PULLUP);
  #define BAUD  115200
  Serial2.setRX(RXD1);
  Serial2.setTX(TXD1);
  Serial2.begin(BAUD);
  delay(100);
}

// main program loop
void loop() {
  delay(10);
}
1 Like
4

???
There is no print statement in the code.

How did you know the encoder was not working?

5

Serial2.println(encoder_state);

6

where?

7

I had such high hopes.

8

Help others help you providing full and complete info.

You shouldnt use Serial.print() in the irq routine.

9

Serial2.println() may not work if called from an ISR.
(Iirc, it’s been made to work on AVRs, but Pico/MBed might be different.)
Try toggling an led or something instead…

(Btw: actual Pico, or nano rp2040? Arduino rp2040 mBed core, or Philhower rp2040 core?)

10

I found the problem: encoder_init() was not being called from setup()
It works fine now :slight_smile:

11

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