DS18S20 instead of DS18B20 gives the wrong value. How I can manage It?

[espruino-discuss3]

Posted at 2014-01-11 by Andrey

Hi,
I know that is because the B20 differs from S20, but could u recomend, how I can get correct temp? Now I have 3,25 °C when real temp is ~25. Will It be correct to just multiple to some koef. and\or shift the value?
Sorry for possible offtop.
Thanks.

[gfwilliams]

Posted at 2014-01-12 by @gfwilliams

Hi, I think there is a thread on this here: http://forum.espruino.com/conversations/317/#comment3172

Please let me know how you get on - it'd be nice to improve the DS18B20 library so it works with both

[espruino-discuss3]

Posted at 2014-01-12 by JumJum

Hello Andrey,
for me it works this way. Type of sensor can be recognized in device info of sensor
regards
Juergen

function OneWireTemp(pin){
  var me = this;
  me.ow = new OneWire(pin);
  me.device = me.ow.search()[0];
  me.deviceType = me.device - ((me.device >> 8) << 8);
  me.readRegister = function(callback,n){
    if(!n)n = 8;
    var reg = [];
    me.ow.reset();me.ow.select(me.device);me.ow.write(0x44,true);
    me.ow.reset();me.ow.select(me.device);me.ow.write(0xBE);
    for(var i = 0; i < n; i++){reg.push(me.ow.read());}
    return reg;
  };
  me.getTemp = function(callback){
    var t,reg = me.readRegister(2);
    t = reg[0] + (reg[1] << 8); if(t > 32767) t -= 65536;
    switch(me.deviceType){
      case 40: t = t / 16; break;//ds18B20
      case 16: t = t / 2; break;//ds18S20
    }
    return t;
  };
}

[gfwilliams]

Posted at 2014-01-13 by @gfwilliams

Hi JumJum,

Thanks! By the way, when you post code in the forum please could you surround it with 3 backticks? See https://help.github.com/articles/github-flavored-markdown#fenced-code-blocks

I've just updated your post above, and it makes it syntax highlight correctly :)