5 Replies Latest reply on Jan 8, 2015 5:49 PM by CMata_Intel

    connect a MCP9701?

    dottedquad

      Nodejs Code:

      var m = require('mraa');
      var a0 = new m.Aio(0);
      a0.setBit(10);
      
      console.log("reading analog input>>>");
      
      /*setInterval(function() {
        readAnalog()
      }, 1000);*/
      
      function readAnalog() {
        var v_out;
        var temp;
      
        v_out = a0.read();
        v_out*=.0048;
        v_out*=1000;
        temp=0.0512 * v_out -20.5128;
        var tempinf = temp * (9 / 5) + 32;
        console.log("c: " + temp.toFixed(1) + " f: " + tempinf.toFixed(1));
      }
      
      readAnalog();
      

       

      I am using a MCP9701.  The MCP9701 is hooked to my Edison Arduino breakout board pin A0, 5v and ground.

       

      The output temp is:

      c: 25.4 f: 77.8

       

      My room temp thermometer say 71.8 and the Edison is calculating my room temp as 77.8.  The temperature is definitely NOT 77.8 in my room.  What am I doing wrong and how do I get the proper temperature calculation using NodeJS?