TMC429 & TMC2660 XActual Response

[harrison181997]

When reading back xactual for a motor while its moving to a target position there are large negative numbers that do not make any sense and then finally it will reach its position and return the correct value.
What is wrong here?

[a-osb]

I am seeing the same thing on TMC5031 using linuxspidev to communicate with it. If I poll XACTUAL too frequently (>30Hz) I get numbers that are far from expected, sometimes every 1 in 10 readings. I suspect that SPI frames are getting mangled. Did you figure out the cause @harrison181997 ?

[a-osb]

I found that the root cause of my issue, despite blocking concurrent access to tmc5031_readWriteSPI , was not blocking concurrent access for the entire duration of a register read, which involves 2 SPI transactions (two calls to tmc5031_readWriteSPI - one to send the request and one to read the reply).

In my case this was not a TMC-API issue.