TMC Stepsticks

Our FluidBoard is outfitted with 4 slots for either TMC steppers or external drivers. We do not recommend using any other type of driver. Most CNC machines need the power that only external stepper drivers can deliver. However, in certain cases, it's useful to add a few small stepper motors for various tasks.

TMC Stepsticks can serve this purpose. We support SPI TMC stepsticks, which implies that you should either use TMC2130 or TMC5160 (normal or pro). The TMC5160 is the more powerful of the two, and should be fine for NEMA-23 motors or smaller ones.

Selecting stepstick voltage

There are two switches for selecting the voltage of the stepsticks. When using TMC stepsticks, select the 3.3v position.

The 5v position is only for external drivers and can destroy your FluidBoard when used with TMC stepsticks.

Each switch is used for 2 stepsticks. You cannot select different voltages for individual stepsticks.

Wiring

The wiring depends on the stepstick you are using. Not all TMC stepsticks use the same layout for A and B coils, and the coils are routed to the screw terminals. Even different versions of the same stepstick might use a different layout. Check your vendor for the correct pinout!

From the stepper end, you can easily determine which coil is A and B by using a multimeter and measuring the resistance. If the resistance is almost zero, the two wires are connected to the same coil. If the resistance is higher, the wires are connected to different coils. Wire two wires of the same coil to A and two wires to B.

Configuration

The YAML configuration for TMC stepsticks is as follows:

tmc_5160: # or tmc_2130:
	step_pin: i2so.16
	direction_pin: i2so.17
	disable_pin: i2so.19
	cs_pin: i2so.18
	r_sense_ohms: 0.050
	run_amps: 1.8
	hold_amps: 1.0
	microsteps: 8
	run_mode: CoolStep
	homing_mode: CoolStep

Pinout

The pinout for the 4 stepsticks is as follows: