HTU21D problem with I2C

First, Run it on Arduino. If it is ok, then convert that code according your MCU.

@legoguy has already done that and reported success further up in this thread

@johnyrobot5 has already mentioned that it works on Arduino.

That’s the whole puzzle:

  • It’s not the hardware (HTU21D breakout board, Particle device)
  • It’s not the software (system firmware, application code)
  • What can it be? The wiring? The combination with the power shield (I guess this was checked already)?