2 Replies Latest reply on Jan 30, 2015 2:02 AM by Ruscoff

    Battery and ADC Operation

    Ruscoff

      Hi all,

        two question about ADC Module on Intel edison Arduino expansion board:

      1) Schematics show that ADC is ADS7951, datasheet says that Vref should be 2.5V and with software function it can double Vref until 5V. So why we tie REFP at Vshield (3.3 or 5) does it may break the ADC?

      2) Why +VA1 and +VA2 are connect to  5V and not to V_system? With battery supply ADC is not powered, would have been better connect it to V_sys?

       

      Thanks

       

      Marco

        • 1. Re: Battery and ADC Operation
          DiegoV_Intel

          Hi Ruscoff,

           

          The REFP input in the schematic has a voltage divider, so the input voltage reference will be divided before go to the ADC REFP pin.

           

          Regarding the second question, the Arduino Expansion Board was designed to be powered through the barrel jack or through the USB port. You could use a plug like this one if you want to power the board with a battery: https://www.google.com/search?q=battery+barrel+jack&espv=2&biw=1600&bih=772&source=lnms&tbm=isch&sa=X&ei=tXDKVJXeIJPioAT…

           

          However, I suppose you are taking about the J2 header, is that right? If so, that header is for attach a battery, but it will act as a backup power only for the Edison module when the main input power isn't present. This backup input power only prevents Edison module to shut down.

           

          Regards,

          Diego.

          • 2. Re: Battery and ADC Operation
            Ruscoff

            Thanks DiegoV.

            Good explanation, i understand all question.

             

            If someone have my same objective i'm going to explain my workaround:

            Connect the battery to J2 header, cut the 5V trace on expansion board and connect the battery + to 5V output in power header.  I'm using an external stepup (TPS60110) to gain 5V from battery.

            5V is big trace that run under POWER and ANALOG IN label of power and analog header.

             

            Regards.

            Marco