Pinout
A4988 stepper driver (StepStick) pinout
Pins
- ENABLE (active low — pulled low on the carrier, so the outputs are live when left unconnected)
- MS1 / MS2 / MS3 (microstep select, pulled low: 000 full, 100 half, 010 1/4, 110 1/8, 111 1/16)
- RESET and SLEEP (active low — tie them together if unused, RESET floats otherwise)
- STEP (one rising edge = one microstep)
- DIR (direction, sampled on each STEP edge)
- VMOT + GND (8–35V motor supply — 100µF capacitor close to the pins!)
- 2B / 2A (coil 2) and 1A / 1B (coil 1) — one motor winding per pair
- VDD + GND (3–5.5V logic)
Specifications
| Motor supply (VMOT) | 8–35 V |
|---|---|
| Logic supply (VDD) | 3–5.5 V |
| Output current | ≈1 A per phase without heatsink; 2 A max with cooling |
| Microstepping | Full, 1/2, 1/4, 1/8, 1/16 |
| Current limit | I = Vref / (8 × Rsense) |
| Sense resistor | 0.068 Ω (Pololu) or 0.1 Ω (many clones) |
| STEP pulse | ≥ 1 µs HIGH and LOW |
| Protection | Over-temperature, under-voltage lockout, crossover-current |
| Capacitor | 100 µF across VMOT/GND |
| Size | 15.2 × 20.3 mm |
Notes
- Set the current-limit pot before connecting a motor: I_max = Vref / (8 × Rsense) on most boards (0.1Ω sense → Vref 0.8V for 1A); measure Vref between the pot screw and GND.
- The DRV8825 uses the same footprint and pin order except pin 10, which is VDD here and FAULT on the DRV8825.
