Implement tmc2208 step+dir+step filter #2565
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The queue_append system predates the iterative solver - it was useful when many different kinematic functions directly added steps to the step compression queues. With the iterative solver being the only source of step generation, it is simpler to directly add steps from the iterative solver code. Signed-off-by: Kevin O'Connor <[email protected]>
Reorder the loop to try and make the code flow a little simpler. Signed-off-by: Kevin O'Connor <[email protected]>
If the stepper changes direction then the average velocity since the last step pulse isn't a good indicator of the next step pulse. Instead, reset the bounds checking to use a low starting guess. Signed-off-by: Kevin O'Connor <[email protected]>
Some stepper motor drivers do not respond well to rapid "step + direction change + step" events. In particular, it is believed this can cause "over current" events on the tmc2208 drivers when they are in "stealthchop" mode. Detect these events and remove them from the generated step times. Signed-off-by: Kevin O'Connor <[email protected]>
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This was referenced Mar 5, 2020
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Unfortunately, it looks like this PR could lead to timing errors due to the filter not flushing steps correctly. I've reverted it for now (as of commit e872290). -Kevin |
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It is not currently valid to run the tmc2208 drivers in "standalone mode" with Klipper due to what appears to be an issue in how the tmc2208 handles direction changes. It is believed that a step followed by a direction change followed by a step in the opposite direction can cause it to experience an "over current" event if the two step pulses occur in a small time period. This is described in the FAQ at https://www.klipper3d.org/FAQ.html#my-tmc-motor-driver-turns-off-in-the-middle-of-a-print .
This PR adds code to filter out rapid step+dir+step sequences. This should, ideally, prevent issues with the tmc2208 - both when they are in standalone mode and in a "stealthchop" mode configured via the uart interface. Some other stepper drivers have been observed to not handle rapid direction changes particularly well and there should be no harm in filtering these events, so this support is enabled for all steppers.
-Kevin