It has been quite some time since moteus gained the ability to be controlled or monitored over a different communication channel. In fact, the last time was with the permanent switch from RS-485 to CAN-FD way back in 2019 with the first moteus-r4. So, I’m happy to share that as of firmware 1.1.2 moteus now has a second supported communication transport out of the box, logic level UART!

Why UART?

Often it is useful to deploy moteus in a system where it is controlled and monitored by a microcontroller, there is only a single moteus controller, and the total distance between the microcontroller and the moteus is short and without significant electromagnetic interference (EMI). In those cases, using a logic level UART on the microcontroller can save the additional complexity and cost of integrating a CAN-FD controller and transceiver into the host system.

Sometimes a bug report comes in that is simple. Sometimes a bug report comes in that is complex. This is the story of a bug report that looked very simple, but in the end was actually much more complex than I had initially expected. Further, it likely contributed to electrical damage on many deployed moteus boards, which is definitely not something I aim to do! Read on to learn more.