Stepper Motor Vref Calculator

Calculate the correct reference voltage for A4988, DRV8825, TMC2208, TMC2209, and other stepper drivers.

Driver Settings

Stepper Driver

Sense Resistor (Ω) Check your driver board — common values: 0.1Ω (A4988), 0.11Ω (TMC2208/2209)

Motor Settings

Motor Rated Current (A) Check your stepper motor datasheet for rated current per phase.

Run Current (% of rated) Recommended: 70-90% of rated current.

Vref Voltage

0.600 V

Set your driver's potentiometer to this voltage

1.20 A

Run Current

—

Formula Used

What is Vref?

Vref (voltage reference) is the voltage on the stepper driver's potentiometer that sets the maximum current delivered to the stepper motor. Setting it correctly prevents overheating and ensures proper motor performance.

Driver Formulas

A4988: Vref = Current × 8 × Rsense
DRV8825: Vref = Current × 5 × Rsense
TMC2208/2209: Vref = Current × 1.41 × Rsense × 1000 / 1000 (simplified: Vref ≈ Current × √2 × Rsense)
TMC2130/5160: Similar to TMC2208 for standalone mode

How to Measure & Adjust

Power off the printer and disconnect motors
Power on the electronics only (USB or 12/24V)
Set multimeter to DC voltage
Place the negative probe on a ground pin
Touch the positive probe to the potentiometer
Adjust with a small screwdriver to match the calculated Vref

Common Motor Currents

Creality 42-34 (Ender 3 X/Y): 0.8A rated
Creality 42-40 (Ender 3 Z/E): 1.5A rated
Nema 17 (generic): 1.0-2.0A rated
LDO motors (Voron): 0.8-2.0A rated

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