Hello, I'm using Arduino Mega 2560 with I2C sensor ADXL345. And I'm using delay(1) to control the sampling interval at 1 millisecond, neamly I should have 1000 sampling points per second. However, the output is far less than 1000, it is only around 80 points per second. The output data rate of the sensor is 800 Hz and the excitation frequency is 1000 Hz. I also tried millis() to control the sampling rate, no developing.
#include <Wire.h>
#include <ADXL345.h>
ADXL345 adxl; //variable adxl is an instance of the ADXL345 library
void setup() {
Serial.begin(9600);
adxl.powerOn();
//set activity/ inactivity thresholds (0-255)
adxl.setActivityThreshold(75); //62.5mg per increment
adxl.setInactivityThreshold(75); //62.5mg per increment
adxl.setTimeInactivity(10); // how many seconds of no activity is inactive?
//look of activity movement on this axes - 1 == on; 0 == off
adxl.setActivityX(1);
adxl.setActivityY(1);
adxl.setActivityZ(1);
//look of inactivity movement on this axes - 1 == on; 0 == off
adxl.setInactivityX(1);
adxl.setInactivityY(1);
adxl.setInactivityZ(1);
//look of tap movement on this axes - 1 == on; 0 == off
adxl.setTapDetectionOnX(0);
adxl.setTapDetectionOnY(0);
adxl.setTapDetectionOnZ(1);
//set values for what is a tap, and what is a double tap (0-255)
adxl.setTapThreshold(50); //62.5mg per increment
adxl.setTapDuration(15); //625us per increment
adxl.setDoubleTapLatency(80); //1.25ms per increment
adxl.setDoubleTapWindow(200); //1.25ms per increment
//set values for what is considered freefall (0-255)
adxl.setFreeFallThreshold(7); //(5 - 9) recommended - 62.5mg per increment
adxl.setFreeFallDuration(45); //(20 - 70) recommended - 5ms per increment
//setting all interrupts to take place on int pin 1
//I had issues with int pin 2, was unable to reset it
adxl.setInterruptMapping(ADXL345_INT_SINGLE_TAP_BIT, ADXL345_INT1_PIN);
adxl.setInterruptMapping(ADXL345_INT_DOUBLE_TAP_BIT, ADXL345_INT1_PIN);
adxl.setInterruptMapping(ADXL345_INT_FREE_FALL_BIT, ADXL345_INT1_PIN);
adxl.setInterruptMapping(ADXL345_INT_ACTIVITY_BIT, ADXL345_INT1_PIN);
adxl.setInterruptMapping(ADXL345_INT_INACTIVITY_BIT, ADXL345_INT1_PIN);
//register interrupt actions - 1 == on; 0 == off
adxl.setInterrupt(ADXL345_INT_SINGLE_TAP_BIT, 1);
adxl.setInterrupt(ADXL345_INT_DOUBLE_TAP_BIT, 1);
adxl.setInterrupt(ADXL345_INT_FREE_FALL_BIT, 1);
adxl.setInterrupt(ADXL345_INT_ACTIVITY_BIT, 1);
adxl.setInterrupt(ADXL345_INT_INACTIVITY_BIT, 1);
}
void loop() {
//Boring accelerometer stuff
int x, y, z;
adxl.readXYZ(&x, &y, &z); //read the accelerometer values and store them in variables x,y,z
// Output x,y,z values
Serial.print("values of X , Y , Z: ");
Serial.print(x);
Serial.print(" , ");
Serial.print(y);
Serial.print(" , ");
Serial.println(z);
double xyz[3];
double ax, ay, az;
adxl.getAcceleration(xyz);
ax = xyz[0];
ay = xyz[1];
az = xyz[2];
Serial.print("X=");
Serial.print(ax);
Serial.println(" g");
Serial.print("Y=");
Serial.print(ay);
Serial.println(" g");
Serial.print("Z=");
Serial.print(az);
Serial.println(" g");
Serial.println("**********************");
delay(1);
}
, I'm still not familiar with Arduino.