TMC223 - clearing stall detection bit

[fritz194]

Somehow, we spent a lot of time with "intermediate effects" due to incomplete TMC223 spec.

1.) If the device somehow ended up in stalled mode (getstatus2 never read out) - these bits survive
the "proper" init sequence.
So its obligatory for using stall detection to read status 2 at init time - otherwise these bits will be set/cleared at first readout.
In our case we used stall detection for referencing - with the effect that the first reading of status 2 during referencing had this bit set
if stall occured "pre-reset".
A state diagram concerning that would be nice to have in the docs + extra init suggestions.

2.) In our application - I set the stalling parameters at init time - expecting that the thing will stop in any situation further on.
This is not the case.
On some movements I just readout status 1 looking at the "moving" bit.
In this situations - the controller doesn´t stop if stalled (!!!!!)
The controller only stops on "stall" if status 2 is read out frequently.
It even looks that the controller checks stalled condition during status 2 readout _ O N L Y _
This means there is some latency on detecting the stall - depending on the polling interval of status 2...

I haven´t checked the newest datasheets so far - but - these fundamental issues should even be documented in a preliminary datasheet.

rgds.

[fritz194]

To clarify 2)
It seems that stall is detected(stall bits set) without polling getstatus2 - but stopping the motor only happens on readout of status2.
If status 2 stall bits set but not read out - and further commands are issued (setpos, ...) - the next reading of getstatus2 wont stop the motor - but will show the set stall flag.

So 1) and 2) is the same thing.

"if stall detection used - clear stall bits by reading status 2"
"automatic stopping on detected stall happens during readout of status 2"
This sounds more like a bug than a feature but my findings go into this direction

[Dr.LarsLarsson (TRINAMIC)]

Thanks for your hints - this will be included into the next version of the datasheet.