The TMC 2209 with UART feedback has a few features:
- M122 can tell you if some things are wrong. It doesn’t always find the issue, but it has flags for over temp, open loop, or shorting to ground.
- The current gets set by the firmware. That is really nice to be able to change things and have a reliable setting. The little trim pots are a pain.
- Features like stealthchop, sensorless homing, don’t really help with CNC. We have those turned off.
- There are features like interpolating the 1/16th microstepping to 1/256th microstepping. And I have heard that the way they measure the current is better, but IDK if I buy any of that.
- The chip is mounted on the bottom, and sinks heat through the PCB. That is supposed to be better for heat dissipation.
The drv8825 was our go-to driver for many years. Before the TMC drivers were available. They work well.