crank_tracker_mini2.ino

/*
 * It is an inexpensive device to motivate children to exercise on a stationary bike; when the children pedal a bike, a movie or song they have chosen plays.
 * It uses a magnet sensor to measure the speed of the pedal or crank of an exercise machine, and has a knob for changing what threshold is fast enough.
 * The microcontroller emulates a keyboard and sends a space key press to start or stop any video or music playing on a computer.
 * Use with a Digispark http://digistump.com/products/1, knob, and magnet sensor.
 * by Joshua, 2015
 */
#include "DigiKeyboard.h"
boolean paused = true;
unsigned long timeSinceCrank = 10000000;
int speedShow = 1;
boolean magt;
boolean magtLas;
  void setup() {   
  pinMode(2, INPUT);//knob
  pinMode(0, INPUT);//sensor
  pinMode(1,OUTPUT);//light-built in
  digitalWrite(1,HIGH);//light
  DigiKeyboard.delay(1400);
  digitalWrite(1,LOW);//light
  DigiKeyboard.delay(300); 
}           
void loop() {
  analogWrite(1,speedShow);//light
  magt = !digitalRead(0);
  if (magt == true && magtLas == true) {
     timeSinceCrank = 1;
    magtLas = false;
  }
  if (magt == false) {
    magtLas = true;
  }
  if (timeSinceCrank < 1000000) {
    timeSinceCrank=timeSinceCrank+map(analogRead(1/*knob*/),0,1023,900,60);
  }
  speedShow = constrain(map(constrain(timeSinceCrank,0,1100000),0,1000000,255,0),0,255);
  if (speedShow > 3 && paused == true) { 
    paused = false;
    DigiKeyboard.write(" ");
  }
  if (speedShow < 2 && paused == false) {
    paused = true;
    DigiKeyboard.write(" ");
  }
}