This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

[FAQ] HDC2080/HDC2010/HDC1080/HDC1010 - Why am I having issues with I2C?

Why am I having issues with I2C? 

  • Common initial I2C issues arise from several directions, from installing correct I2C pullups to correct addressing of devices on the bus, to point out two common initial issues seen with I2C communications.

    I2C is an open drain bus, therefore there must be pullup resistors installed. These resistors must be chosen or changed based on the bus capacitance. If the bus capacitance is high (towards 400pF) and the pullup resistor value is not low enough then the signal will be more rounded and may cause issues with edge detection. Texas Instruments provides a short application note on this topic with example of how to calculate the pullup resistor values here: http://www.ti.com/lit/an/slva689/slva689.pdf

    The correct addressing of the intended slaves on the I2C bus, from the master to the slave is critical to success, too. The slave will Not ACKknowledge (NACK) any command not addressed specifically for it by remaining silent on the bus. The HDC family of devices has a default 7-bit address of 0x40, which translates to 0x80 and 0x81 for writes and reads, respectively, when completing the full 8 bits of the hexadecimal byte sent over the I2C bus.