Home Page Forums Raspberry Pi Shields Cellular IoT HAT/Shield + other I2C slaves

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    I’m trying to move from using the Cellular IoT HAT to the Cellular IoT Shield thanks to its additional features.

    When I was using the HAT, I had a working I2C slave connected through the GPIOs. Now with the Shield though the I2C slave cannot initialize.

    My question is therefore: Is there some additional setup required other than the usual raspi-config settings?

    I’ve tried connecting the I2C slave between the RPi and the Shield using a perfboard, as well as using the Shield’s external I2C header. Alas, neither methods worked.

    Also, before trying all this, I make sure the Shield is correctly powered on via your python library and my I2C slave is detected by the RPi.

    (To be a bit more specific, HW-wise I’m using Sparkfun’s Sensor Stick, which is a 9-DOF IMU communicating via I2C and SW-wise I’m using RTIMULib)

    Thanks a lot for your help!! 🙂

    • This topic was modified 6 months, 2 weeks ago by Marc. Reason: Added the fact that I check that the I2C slave is detected by the RPi


    Could you please run this script with Cellular IoT Application Shield.

    Any error log will help us to understand the error.



    Thank you for your reply. My previous message wasn’t using the correct full name of the product. When I was saying IoT HAT, it was the Cellular IoT HAT (on the black PCB), whereas when I was saying IoT Shield, it was the Cellular IoT Application Shield (on the blue PCB).

    Both were working independently, and the issue arose only when trying to use both with the RPi simultaneously. However, I found out this morning what my issue was: albeit the Sensor Stick’s magnetometer’s I2C address can be either 0x1C or 0x1E (I was obviously using the latter to prevent collision with the Cellular IoT Application Shield’s accelerometer), the library I was using was probing the 0x1C address first, so the MMA8452Q was replying, but not what the RTIMULib library expected.

    Therefore my issues were SW-related, but not due to your product nor library ^^’

    I fixed it by rearranging the address priorities in my copy of RTIMULib.

    Thanks for your help anyway!

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