Driver Mode Mismatch: UART vs. Standalone Configuration Conflict

A common wiring-related failure occurs when the TMC2209 driver is physically configured for UART mode via jumpers or solder bridges on the mainboard, while the user intends to operate it in standalone (Step/Dir/En) mode. In this state, the driver's internal logic expects configuration and movement commands exclusively through the serial (PDN_UART) pin. Consequently, the driver ignores the physical Step, Direction, and Enable signals sent by the MCU, rendering the motor unresponsive despite correct wiring to the standard pins.