Hangs when connecting to multiple odrives using find_any()

[Patrick-Thomas]

I'm trying to control two ODrives inside a Python3 script. Both ODrives (v3.6-56V) are running the latest firmware version (fw-v0.5.2), and both appear when I open odrivetool (v0.5.2.post0). In Python I can instantiate either ODrive using find_any(serial_number="xxx"), however when I try to instantiate them sequentially I get a couple of warnings ([LEGACY_PROTOCOL] received unexpected ACK: 129) and the script hangs.

I am running Ubuntu 18.04, and the ODrives are not connected via a USB hub. I've tried each of the usb_cdc_protocol settings for each ODrive but none of them work.

[Fallstop]

This also affects me, on Ubuntu 21.04, fw-v0.5.2, ODrives v3.5-24V.
Example code to trigger the bug:

odrv_0 = odrive.find_any(serial_number="XXX")
odrv_1 = odrive.find_any(serial_number="XXX")

This appears to be a regression in Odrivetool v0.5.2.dev0, as this version does connect to both odrives.

[samuelsadok]

This is because find_any() starts a fibre.Domain internally which remains open for the lifetime of the ODrive objects. Since Fibre currently doesn't support multiple concurrent domains, the second find_any() will run into problems.

I rewrote find_any() now so that only one single Domain is started that remains open until the program is terminated. All subsequent find_any() calls make use of this first Domain.

I pushed the fix to fw-0.5.3.