Dirty SPI signal with AS5048A magnetic encoder

hardware support
1

Hi all,

I am trying to read the angle data from a AS5048A magnetic sensor with SPI protocol. The readout value is reasonable and would change as the motor rotate, but the raw signal shows some spikes whose frequency seems to be twice the clock frequency (please see the image below, which is the measurement from the MISO pin).

I am troubleshooting because my angle reading suffered from random jittering when two AS5048A are connected to the same SPI bus.

Could anyone perhaps give me some advise on this issue? Thank you :slight_smile:

vlcsnap-2022-09-12-23h28m05s693
vlcsnap-2022-09-12-23h28m05s6931920×1080 120 KB

2

Hey, there is definitely something wrong here…

What speed is the SPI set to? Does this noise change when you change the SPI speed, or does the noise stay at the same frequency?
It’s so regular I would say it has to be due to the SPI clock itself or another clock or PWM source…
Also it looks like you have 3 voltage levels in there…

Could you post a circuit diagram for this?