I need a help.... I have Rpi Zero W + GY-PCM5102

it's wired by pins Vcc 5v, GND, PIN 12, 35,40 on RPI, and it's work fine as HifiBerry DAC on MoodeAudio or Volumio.

BUT IT's works ONLY when I touch with fingers some of PCB parts of PCM or Rpi! What can be wrong??? some more GND pins? or what? thank you...

1 Answer 1


Sounds like you may have some floating inputs, i.e. logic inputs that are not pulled or driven high or low. Some times when you touch floating inputs, it sets them at a particular logic level. You can try probing the pins individually with a 10K resistor on a wire tied to 3.3V or GND and see which exact pins are causing the problem.

  • YES, YES! VIN -> 10K -> SCK, and it's work perfect!
    – Juraj P.
    Feb 15, 2018 at 5:55
  • Actually, since the problem was fixed by adding a pullup to SCK, that might indicate a timing issue. Putting you finger on pins adds a small amount of capacitance, which slows down the signal. Adding the 10K pullup to SCK will be in parallel with the existing I2C pullup, which makes the rise time faster. It may be that touching the SDA pin slowed it down enough to be equivalent to speeding up SCK by adding an additional pullup. In any case, if it works with the 10K pullup then that is what matters most.
    – crj11
    Feb 15, 2018 at 14:04

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