LIS3DH not responding. Maybe pullup resistor strength or interrupt pin connection.

RKeit.1 · ‎2020-04-08

Hi All,

I have been using the LIS3DH for years and have always found it trouble free.

I have a very small board with an MCU, an Si7051 temperature sensor and an LIS3DH. The two sensors share the same very short I²C bus. There are 10 kΩ pullup resistors on SDA and SCL. The two interrupt pins of the LIS3DH are connected directly to two pins on the MCU. SD0/SA0 is connected directly to ground, a setup I have used before.

The LIS3DH is not responding at all. I can't get an ACK or anything else. I can communicate with the temperature sensor. I have tried bus speeds between 10 kHz and 92 kHz. I have also tried several different configurations for the two MCU pins to which the INT pins are connected. They are open drain inputs.

Could the pullup resistors be too weak? I have used LIS3DH alone with 10 k before but not shared with another device.

Would tying the two INT pins to ground, albiet via a weak pull-down cause the LIS3DH to be unresponsive? I have always found these outputs to be robust. It is just a thought. Should I put a resistor between the each INT pin and the MCU pin? It is a seriously small board and finding space would be hard.

Any clues would be appreciated.

Thanks in advance,

Rob

RKeit.1 · ‎2020-04-09

I found the problem. I am dealing with an LIS3DSH, not an LIS3DH. It is all working fine.

darla14 · ‎2020-11-04

what change you spotted which solves the issue.Can you please elaborae. It will help others.