There’s an updated release out for the mjbots pi3hat which features a useful bug fix and a minor feature.

First, the configuration of automatic retransmission was broken in several ways. The symptoms for previous versions would be that any attempt to change the CAN configuration for a bus would result in all channels attached to that controller having auto-retransmit turned off. Since it was by default on, that would typically result in a decrease in transmission reliability, and in some particular cases with arbitration conflicts, could result in frequent packet loss. Fixing this requires updating both the firmware on the device and the C++ and python libraries. Fortunately, this would only come up if you were communicating with non-moteus devices using the pi3hat, which likely isn’t that common.

The moteus brushless controller can drive many motors out of the box, but until now it has been challenging to use with gimbal style brushless motors. They are wound with thin wire so that they have a very high winding resistance, and thus can be driven by inexpensive low current controllers. Using something like moteus with a gimbal motor isn’t absolutely necessary, but does give benefits in terms of high performance trajectory tracking and torque control.

The initial implementation of auxiliary encoders for moteus supported exactly one encoder, the AS5048B. The hardware can support any I2C based encoder, so supporting additional encoders has always been on the TODO list.

I’m excited to announce, that as of firmware release 2021-12-03, AS5600 encoders are now supported as well. They are a lot cheaper than the AS5048 as they have a much lower update rate and resolution, but that isn’t necessarily a problem if it is only used to disambiguate a modest gear reduction.