Watermark Interrupt does not work with attachInterrupt()

[sheikhumar93]

Hi, I have been trying to run the FIFO example provided by this library along with the attachInterrupt() function provided by Arduino. The Fifo code on its own runs very well, but it doesn't actually change the state of the pin INT1 on the ADXL345 -> D3 on the Arduino Pro Mini. It always remains HIGH.

Here's my code:

#include <Wire.h>
#include <ADXL345.h>
#include <LowPower.h>

ADXL345 adxl;

const byte interruptPin = 3;

void setup() {
  Serial.begin(115200);
  // put your setup code here, to run once:
  adxl.powerOn();
  adxl.setLowPower(1);

  //look of activity movement on this axes - 1 == on; 0 == off
  adxl.setActivityX(1);
  adxl.setActivityY(1);
  adxl.setActivityZ(1);

  //setting all interrupts to take place on int pin 1
  adxl.setInterruptMapping(ADXL345_INT_WATERMARK_BIT,     ADXL345_INT1_PIN);

  //register interrupt actions - 1 == on; 0 == off
  adxl.setInterrupt( ADXL345_INT_DATA_READY_BIT, 0 );
  adxl.setInterrupt( ADXL345_INT_SINGLE_TAP_BIT, 0);
  adxl.setInterrupt( ADXL345_INT_DOUBLE_TAP_BIT, 0);
  adxl.setInterrupt( ADXL345_INT_FREE_FALL_BIT,  0);
  adxl.setInterrupt( ADXL345_INT_ACTIVITY_BIT,   0);
  adxl.setInterrupt( ADXL345_INT_INACTIVITY_BIT, 0);
  adxl.setInterrupt( ADXL345_INT_WATERMARK_BIT, 1);

  //setting lowest sampling rate
  adxl.setRate(12.5);
  //setting device into FIFO mode
  adxl.setMode(ADXL345_MODE_FIFO);
  //set watermark for Watermark interrupt
  adxl.setWatermark(25);
}

void wakeUp()
{
  Serial.println("I just woke up...");
}

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

  adxl.getInterruptSource();  // reading interrupt status flags
  Serial.println("Going to sleep...");
  attachInterrupt(digitalPinToInterrupt(interruptPin), wakeUp, CHANGE);
  LowPower.powerDown(SLEEP_FOREVER, ADC_OFF, BOD_OFF);
  detachInterrupt(digitalPinToInterrupt(interruptPin));

  int x[25], y[25], z[25];
  byte fifoentries, intEvent;
  fifoentries = adxl.getFifoEntries();
  intEvent = adxl.getInterruptSource();  // reading interrupt status flags
  if (adxl.triggered(intEvent, ADXL345_WATERMARK) )  // if watermark interrupt occured
  {
    Serial.println("Watermark interrupt triggered. Fetching data now." );

    if (fifoentries != 0) {
      // burst read will cause the fifo to empty
      adxl.burstReadXYZ(&x[0], &y[0], &z[0], fifoentries); // reading all samples of FIFO
      for (int i = 0; i < fifoentries; i = i + 5) //Printing only every 5th sample to prevent spam on console
      {
        Serial.print("FIFO data sample: ");
        Serial.print(i);
        Serial.print(", x: ");
        Serial.print(x[i]);
        Serial.print(", y: ");
        Serial.print(y[i]);
        Serial.print(", z: ");
        Serial.println(z[i]);
      }

    }
  }
}

I have tried to read the value of D3 using digitalRead(3) at various points in the loop and it always returns HIGH, shouldn't it be LOW when the program starts and then switch to HIGH once the watermark interrupt is set, then go back to LOW when the FIFO buffer is cleared?