3 Replies Latest reply on Mar 24, 2017 3:40 PM by SergeyK

    BATMON pin and Pull-Up Resistor value.

    WaterproofBoy

      Hi, its a pleasure to be here.

       

      I have looked into a lot of 3rd party schematic and they all have a pull-up resistor on pin 32 (a.k.a. F1, GPIO1 [by default], SPI_M_SS1, AI1). I am not sure why everyone use BATMON (probably batery monitor) name for this pin even if they not use any battery. So...

       

      • Is that pull-up resistor on pin 32 necesary for running the code or programming the chip?
        2.PNG
      • Why all use 562K pull-up value? Is not that value to high for IO 3.3V or 1.8V?
        1.PNG


      Thanks.

        • 1. Re: BATMON pin and Pull-Up Resistor value.
          SergeyK

          Hi,

           

          It appears that you're looking at my schematic :-)

           

          I think there is an error there, and the F1/AI1 pin of Quark D2000 MCU should be actually connected to DVDD, the voltage produced by the Quark D2000 internal 1.8V regulator, instead of the PVDD/VCC, which is the battery voltage.

          If connected that way, it is possible to measure the battery voltage using the ADC: The ADC reference voltage is internally connected to AVDD (the battery voltage), so that reading the ADC input AI1 will give the ratio of 1.8V to AVDD/battery voltage.

           

          The value of the pull-up resistor is not really important. The ADC input sinks a negligibly low current, so the voltage on F1 will be equal to PVDD.

           

          Thanks,

          Sergey

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          • 2. Re: BATMON pin and Pull-Up Resistor value.
            WaterproofBoy

            Thank you so much for the useful and quick response. So theoretically..

             

            • What should happen if I let that pin floating?
            • It has a firmware or SoC specific functionality?
            • 3. Re: BATMON pin and Pull-Up Resistor value.
              SergeyK

              If you don't need the battery voltage measurement functionality, you can leave pin F1 floating, or use it for some other function. Of course if it is not connected and you'll try to read it - you'll get some random values.

              The firmware (QMSI or Zephyr RTOS) don't assume anything particular about this pin, and as far as I know they don't implement the battery monitoring functionality.

              From the Quark D2000 MCU perspective pin F1 can be used for the following functions:

              1. GPIO (function 0)

              2. Analog input  (function 1)

              3. SPI slave select #1  output (function 2)

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