Distance Sensing Robot

This Robot uses an HC-SR04 Ultrasonic distance sensor, an Espruino board with an L293D motor driver IC soldered onto the surface mount prototyping area.

Note: This is an older code example that doesn't use the HC-SR04 library.

Wiring Up

Solder the L293D motor driver, and the HC-SR04 Ultrasonic Distance sensor as described on their pages

Connect the motors as follows:

Source Code

var TRIG = A0; // ultrasonic trigger
var ECHO = A1; // ultrasonic echo signal
var MOTORS = [A3,A2,B10,B11]; // pins for the motors

var t1 = 0;
var dist = 0;
var inManouver = false;

// Get the distance from the sensor
setWatch(function(e) { t1=e.time; }, ECHO, { repeat:true, edge:'rising'  });
setWatch(function(e) { var dt=e.time-t1; dist = (dt*1000000)/57.0; },  ECHO, { repeat:true, edge:'falling' });
// 20 times a second, trigger the distance sensor
setInterval("digitalPulse(TRIG,1, 10/1000.0)",50);

// reverse, turn, and go forwards again
function backup() {
  inManouver = true;
  digitalWrite(MOTORS, 5); // back
  setTimeout(function() {
    digitalWrite(MOTORS, 6); // turn
      setTimeout(function() {
        inManouver = false;
        digitalWrite(MOTORS, 6); // forward again
      }, 500);
  }, 500);
}

function forward() {
   digitalWrite(MOTORS, 10);
}

function stop() {
   digitalWrite(MOTORS, 0);
}

function onInit() {
  forward();
}

function step() {
  // if we detect we're getting too close, turn around
  if (dist < 20 && !inManouver) 
    backup();
}

setInterval(step, 100); // check every 100ms to see if we're too close
onInit(); // start going forwards