Setup: I have an Adafruit ADXL345 attached to an Adafruit feather 32u4 (LoRa), via I2C lines and an interrupt line.
Goal: The microcontroller should be in a sleep condition when acceleration values are below a certain value (threshold), and stay awake in all other cases. Interrupts make the microcontroller wake up.
Problem: Everything works perfectly most of the time. However when I start tapping a lot on the setup, it seems to get stuck after some time (sometimes after a few seconds, other times after a few minutes of intense tapping). Usually it gets stuck in the state where the LED is off. My suspicion is a race condition.
I have consulted stderr, Nick Gammon Notes.
Any help much appreciated. N.B. I reduced the code to the bare minimum which still reproduces the error, so the whole LoRa part is taken out of the code.
#include <Arduino.h>
#include <avr/sleep.h>
#include <SparkFun_ADXL345.h> // SparkFun ADXL345 Library
#include <pins_arduino.h>
#define LED_BUILTIN 13
#define VBATPIN A9
#define ADXL345_MG2G_MULTIPLIER (0.004) // 4mg per lsb
#define SENSORS_GRAVITY_STANDARD (9.80665F)
volatile bool is_asleep = false;
volatile int isr_counter;
ADXL345 adxl = ADXL345(); // USE FOR I2C COMMUNICATION
/// INTERRUPT
int interruptPin = 1; // Setup pin X to be the interrupt pin
float ab_accY;
// Offset due to gravity/sensor
float gYoffset;
/* Declare functions */
void sleepNow();
void wake();
int digPinToInterrupt();
void setup()
{
pinMode(LED_BUILTIN, OUTPUT);
digitalWrite(LED_BUILTIN, HIGH);
delay(2000);
Serial.begin(9600);
// ***************** SETUP ADXL 345 ****************************
adxl.powerOn(); // Power on the ADXL345
adxl.setRangeSetting(16); // Give the range settings
// Accepted values are 2g, 4g, 8g or 16g
// Higher Values = Wider Measurement Range
// Lower Values = Greater Sensitivity
adxl.setRate(100); // Sampling rate to 100 Hz
adxl.setActivityXYZ(0, 1, 0); // Set to activate movement detection in the axes "adxl.setActivityXYZ(X, Y, Z);" (1 == ON, 0 == OFF)
adxl.setActivityThreshold(20); // 62.5mg per increment // Set activity // Inactivity thresholds (0-255)// (default 75)
adxl.setInactivityXYZ(0, 0, 0); // Set to detect inactivity in all the axes "adxl.setInactivityXYZ(X, Y, Z);" (1 == ON, 0 == OFF)
adxl.setTapDetectionOnXYZ(0, 0, 0); // Detect taps in the directions turned ON "adxl.setTapDetectionOnX(X, Y, Z);" (1 == ON, 0 == OFF)
adxl.setInterruptMapping(ADXL345_INT_ACTIVITY_BIT,ADXL345_INT2_PIN);
adxl.InactivityINT(0);
adxl.ActivityINT(1);
adxl.FreeFallINT(0);
adxl.doubleTapINT(0);
adxl.singleTapINT(0);
float offYsum = 0;
// 10 seconds worth of measurements (assuming 100 Hz)
for (int j = 0; j <= 1000; j++)
{
// Accelerometer Readings
int x,y,z;
adxl.readAccel(&x, &y, &z); // Read the accelerometer values and store them in variables declared above x,y,z
float accY = 0.3065 * y;
offYsum += accY;
}
gYoffset = offYsum/1000;
pinMode(interruptPin,INPUT_PULLUP);//Set pin d2 to input using the builtin pullup resistor
Serial.println("End of setup");
}
void loop()
{
int x,y,z;
adxl.getInterruptSource();
adxl.readAccel(&x, &y, &z); // Read the accelerometer values and store them in variables declared above x,y,z
float accY = 0.3065 * y;
ab_accY = abs(abs(accY) - abs(gYoffset));
float measThresh = 3;
if ( ab_accY <= measThresh)
{
sleepNow();
}
else
{
/* Continue */
}
}
/* --------------------------HELPER FUNCTION----------------------------- */
int digPinToInterrupt(int digPin) {
int intPin;
if (digPin == 1){
intPin = 3;
// return intPin;
}
else if (digPin == 0)
{
intPin = 2;
// return intPin;
}
else {
}
return intPin;
}
// ------------------------ INTERRUPT ROUTINES -------------------- //
void wakeUp(){
if (is_asleep)
{
sleep_disable();
detachInterrupt(digPinToInterrupt(interruptPin));
digitalWrite(LED_BUILTIN, HIGH);
isr_counter++;
is_asleep = false;
}
}
void sleepNow()
{
delay(10);
if (!is_asleep)
{
set_sleep_mode(SLEEP_MODE_PWR_DOWN);
noInterrupts();
sleep_enable();
digitalWrite(LED_BUILTIN, LOW);
is_asleep = true;
attachInterrupt(digPinToInterrupt(interruptPin),wakeUp,HIGH);
interrupts();
sleep_cpu();
}
}
The UART suggestion is a good one thanks, I am not familiar with it. I will look into it.