1.67 clock offset

Hi All,

I have two espruino's both with:

http://www.espruino.com/Clocks

The 32Khz Watch Crystal soldered onto it. I tried the clock example from that page as well as my own implementation and there is quite a big drift: depending on which espruino I use, 1 - 3 seconds on the minute.

Did anyone else notice this?

The program I want to use this for is a simple light switch. On in the morning, off in the afternoon.

var hours = 21;
var minutes = 58;
var seconds = 0;

var port = {pin:C6, brightness:0};
var fadeInterval = 5;

function timestep() {
  seconds += 1;
  if (seconds == 60) {
    seconds = 0;
    minutes += 1;
  }
  if (minutes == 60) {
    minutes = 0;
    hours += 1;
  }
  if (hours == 24) {
    hours = 0;
  }
  updateBehaviourFade();
}

/**
 * This fades in the lights on the port.pin
 * @param {Number} fadeInterval | time in seconds to fade in
 */
function fadeIn(fadeInterval) {
  if (port.brightness == 0) {
    analogWrite(port.pin,1/255);


    var fadeInID = setInterval(function () {
        port.brightness += 1/255;
        if (port.brightness > 1) {
          analogWrite(port.pin,1);
          port.brightness = 1;
          clearInterval(fadeInID);
        }
        else {
          analogWrite(port.pin,port.brightness);
        }
      },
      fadeInterval*1000/255
    );
  }
}

/**
 * This fades out the lights on the port.pin
 * @param {Number} fadeInterval | time in seconds to fade out
 */
function fadeOut(fadeInterval) {
  if (port.brightness == 1) {
    analogWrite(port.pin,1 - 1/255);
    var fadeOutID = setInterval(function () {
        port.brightness -= 1/255;
        if (port.brightness < 0) {
          port.brightness = 0;
          analogWrite(port.pin,0);
          clearInterval(fadeOutID);
        }
        else {
          analogWrite(port.pin,port.brightness);
        }
      },
      fadeInterval*1000/255
    );
  }
}

function updateBehaviourFade() {
  if (hours >= 8 && port.brightness == 0) {
    fadeIn(fadeInterval);
  }
  if (hours >= 23 && port.brightness == 1) {
    fadeOut(fadeInterval);
  }
 }

function onInit() {
  analogWrite(C6,0);
  setInterval(timestep,1000);
}

Would the fading interfere with the clock?

Regards,

Alex

PS. also the fading isn't linear.. it seems to be faster and slower during the fading cycle.