The idea of the slouch detector is simple. If the current angle sensed by the Circuit Playground (currentAngle) exceeds a preset value (SLOUCH_ANGLE), then we are slouching and should sound an alarm. We can achieve this with a simple modification of our previous sketch. Here's the code.
///////////////////////////////////////////////////////////////////////////////
// Circuit Playground Slouch Detector v1
//
// Compute current angle using accelerometer and compare
// to preset slouch angle. Sound alarm if slouching.
//
// Author: Carter Nelson
// MIT License (https://opensource.org/licenses/MIT)
#include <Adafruit_CircuitPlayground.h>
#define SLOUCH_ANGLE 10.0 // allowable slouch angle (deg)
#define GRAVITY 9.80665 // standard gravity (m/s^s)
#define RAD2DEG 52.29578 // convert radians to degrees
float currentAngle;
///////////////////////////////////////////////////////////////////////////////
void setup() {
// Initialize Circuit Playground
CircuitPlayground.begin();
}
///////////////////////////////////////////////////////////////////////////////
void loop() {
// Compute current angle
currentAngle = RAD2DEG * asin(-CircuitPlayground.motionZ() / GRAVITY);
// Check if slouching
if (currentAngle > SLOUCH_ANGLE) {
// Sound alarm
CircuitPlayground.playTone(800, 500);
}
}
The preset angle is defined globally at the top of the sketch.
#define SLOUCH_ANGLE 10.0 // allowable slouch angle (deg)
And then a simple if statement is used to check for slouching.
// Check if slouching
if (currentAngle > SLOUCH_ANGLE) {
// Sound alarm
CircuitPlayground.playTone(800, 500);
}
With the above sketch loaded and running on the Circuit Playground, you should hear the alarm sound if the tilt (slouch) angle is greater than 10 degrees.
