Step-/Direction to SPI converter for TMC23X/24X stepper driver family

The TMC-401 converts step/direction signals into SPI datagrams that can be used to drive a TMC236, TMC239, TMC246 or TMC249 stepper motor driver chip directly. It provides five different microstep resolutions (from 1/32 to 1/2) as well as two full step resolution modes. The StallGuard? bits of a TMC246 or TMC249 motor driver are output on three pins, in order to allow an easy usage of the StallGuard feature. Also the overtemperature pre-warning bit is output on one extra pin (and can be used to shut off the driver when there is an overtemperature pre-warning condition). The TMC-401 also provides a feature that reduces the motor current to 25% when there have not been any step pulses for at least one second. This features can be enabled or disabled. Mixed Decay can also be enabled or disabled using a dedicated pin.