SDO from BMI323 sends weak signal level

[Smartin]

Hello community,

I'm trying to hook up a BMI323 with my CC1311 eval board from TI.
The devices are connected via SPI.
When I read out the Chip ID by sending two bytes (0x80 and 0x00) I get 0x00 (without external pull-ups) or 0xFF (with external pull-ups) as response which is wrong.

After connecting my Oscilloscope I realised that the MISO signal from the BMI323 barely changes the voltage levels. I tried with and without external 10kOhms pull up resistors but that didn't help.

Here are the measured signals:

The blue signal is MOSI, the yellow signal is MISO. MOSI looks like expected while MISO is bouncing around the high level (pull-ups in place). The signal is too weak to be processed by my µC.

Is my sensor defect or do I have to send something via SPI upfront to make MISO work properly?

Thanks a lot in advance for your help.

Best regards,
Martin

[BSTRobin]

Hi Smartin,

I run BMI323 example code on github(https://github.com/boschsensortec/BMI323-Sensor-API/tree/main/examples) under COINES environment and capture SPI waveform which record how to read chip ID for your reference.

Your waveform does not contain clock information and cannot see the complete time sequence. It is recommended that you use a logic analyzer to capture the SPI waveform for easy analysis.