TMC2209 V1.2 VS TMC2208, more of these functions:1. Blocking rotation detection. Stallguard–TMC2209 provides a load and loss of speed detection technology
2. Current dynamic adjustment. Coolstep–TMC2209 provides a current dynamic regulation technology that saves up to 75% of electrical energy.
The hardware of the modes UART,DIR/STEP is the same. If you need to use UART mode, just need to modify the firmware.