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Release status: working

TMC2100 preview.jpg
Description TMC2100 stepper driver
License CC-BY-SA
Author Skimmy
Based-on unknown
Categories surface-mount electronics; stepper motor drivers; Electronics;
CAD Models watterott/SilentStepStick Eagle source files
External Link

TMC2100 are the quietest Pololu compatible stepper motor drivers currently available on the market. The size corresponds to the popular Pololu drivers: the pinout is compatible, but not identical. The driver can be used on all major electronics, eg 8-bit electronics as RAMPS, Rumba, GT2560 or 32-bit electronics as RADDS or AZSMZ and all other Pololu compatible RepRap electronics.



  • Driver-IC: TMC2100, noiseless operation (in certain modes)
  • Hardware compatible with Step Stick and Pololu A4988
  • 1.25A RMS continuous current (equivalent to about 1,77A Imax)
  • short-time peak current 2.5A per motor coil
  • Step/Dir interface with micro-step function (interpolation of up to 256 micro-steps)
  • Motor voltage: 5...45V
  • stealthChop mode - for a noiseless operation
  • spreadCycle mode - for a high dynamic and torque

Special features in comparison to other stepper motor drivers

The TMC2100 stepper motor drivers a few peculiarities must be observed.

  • The driver board is "upside down" mounted, with the chip and the potentiometer down. To allow this, the pinout is mirrored too.
  • The heat sink is mounted on the circuit board on the back. This is much better, because the heat is much better guided by the heat pipes of the board, than the thick plastic layer of the chip itself.
  • The potentiometer is mounted upside down and adjustable via a hole through the board.
  • The "spreadCycle" operating mode is recommended for use in 3D printers. This guarantees sufficient torque for 3D printers; also, this is a very quiet mode.
  • The "stealthChop" operating mode is noiseless, but it can often lead to step losses since the torque is considerably reduced.

Pin Configuration

Since many different electronic boards available such as RAMPS, RADDS, RUMBA, etc, the wiring of config pins (CFG1, CFG2 and CFG3) is solved differently, so it's recommended not to connect config pins. This prevents that change of the electronics implies adjusting the driver. Be joined, that the "spreadCycle" mode also needs the pin CFG1 connected to GND. This can be realized by a small wire bridge (see photo).

Some Chinese boards have been seen in the wild that have CFG1-3 printed out of order on the bottom of the PCB. So CFG3 is connected to MS1 and is actually CFG1 (see photo). Because the configuration pins ship open, you must close them by bridging with solder as shown in the photo in addition to connecting MS1 to GND.

The pins and DIAG1 DIAG2 have no function and may also be omitted.

Various operating modes to provide a through connection of the 3 config pins that green highlighted line is the recommended operation mode:

CFG1 CFG2 Schrittteilung Interpolation Mode
GND GND 1 (full step) none spreadCycle
VCC GND 2 (half-step) none spreadCycle
open GND 2 (half-step) 256 µ-Schritte spreadCycle
GND VCC 4 (quarter-step) none spreadCycle
VCC VCC 16 µ-steps none spreadCycle
open VCC 4 (quarter-step) 256 µ-steps spreadCycle
GND open 16 µ-steps 256 µ-steps spreadCycle
VCC open 4 (quarter-step) 256 µ-steps stealthChop
open open 16 µ-steps 256 µ-steps stealthChop


circuit diagram
wiring diagram
CFG Pins
pin assignment
top view (spreadcycle)
bottom view (spreadcycle)
Vref pins
bottom view (spreadcycle, mislabeled chinese pcb solder bridge)
top view (spreadcycle, mislabeled chinese pcb)

Setting the reference voltage / motor current

The best way to adjust the motor current, the voltage at Vref-Pin (0 - 2,5V)to measure and then adjust the potentiometer. The maximum continuous current is 1,25A (Irms) or 1,77A (Imax) and is determined by the 0,11Ω-sense resistor.

Chinese PCB's have been reported with a 6.8k Ohm potentiometer instead of 20k. This limits the maximum current significantly.

These steppers require active cooling over Vref voltages of around 0.55.

Formulas for calculating the values:

Irms = (Vref * 1.77A) / 2.5V

Irms = Vref * 0.71

Imax = 1.41 * Irms

Vref = (Irms * 2.5V) / 1.77A

Vref = Irms * 1.41

Vref = Imax

Example: A voltage of 1.0V at the VREF pin sets the motor current to 0,71A Irms / 1A Imax.

Vref = (Irms * 2.5V) / 1.77A

1V = (0,71A * 2.5V) / 1.77A

Please note: In some stepper motor drivers, such as the A4988, it represents the maximum current (Imax) with other the RMS current (Irms), such as the TMC2100.

Further information

Github: SilentStepStick

Summary PDF: File:SilentStepStick v1.0 summary.pdf

Sources and where to get it:

RobotDigg (will charge lots for shipping, theres a reason they don't list shipping rates) PL; if need in English, ask by contact form.