Add clear errors

[kenconnor]

Taking over #14
The former PR broke file structure and I made a brand new PR.

I tested it on S1. I called /request_axis_state with wrong state, called /clear_errors and then called /request_axis_state with correct state. I confirmed that procedure_result is changed to 0.

[samuelsadok]

I tested it on S1. I called /request_axis_state with wrong state, called /clear_errors and then called /request_axis_state with correct state. I confirmed that procedure_result is changed to 0.

To be clear, an explicit clear_errors call should not be considered a requirement for entering CLOSED_LOOP_CONTROL. On a high level, an explicit call to clear_errors should only be used to make the LED not be red. See explanation here. If entering CLOSED_LOOP_CONTROL is the goal, clearing errors should be handled transparently by (future) ODrive firmware, or, for compatibiliy with older firmware, transparently in request_state_callback().

If clearing the LED color is the goal of this PR, then the approach looks mostly good. The git history is still a bit convoluted and the PR contains unrelated formatting changes. Please use git rebase / cherry-pick / amend so that the PR consists of a single commit and doesn't contain unrelated formatting changes. Please also add a note in README about the new service call.

[kenconnor]

I think S1 needs to call clear_errors() to re-enable the brake resistor, but under what circumstances is the brake resistor disarmed? Since I use S1, I would like to enable and use the brake resistor if it is disabled.

I made the following edits:

• Removed whitespace unrelated to the PR from the commit
• Added to the README

I was concerned that the contribution of liborw in #14 might disappear, so I decided not to consolidate the commits to preserve the commit history. Should we consolidate all changes, including the additions to the README, into a single commit (add service to clear errors)?

[samuelsadok]

Yes that's true, if you need the brake resistor in your system to be running even if the motor is off (e.g. to sink power from another ODrive), then that's another reason to call clear_errors(). The brake resistor disarms on conditions that specifically restrict the brake resistor's ability to run safely: overvoltage, undervoltage, configuration error and low level system error. We're considering to change this in future firmware versions to re-enable it automatically when the conditions allow it.

Formatting looks good now.

If you wish to preserve authorship, there are multiple ways to do it. E.g. you can still squash the original commits into one, and put additional changes in a separate one, or mention co-authorship in the commit message.

[kenconnor]

@samuelsadok
I have made the following changes:

• Squashed original commits
• Left Libor as a co-author
• Changed the sentence in README

[samuelsadok]

looks good, thanks!