FOC NEMA17 Stepper Motor Driver

KiCad STM32F103CBTx DRV8844 FOC CAN bus Magnetic encoder 4-layer PCB

Front side 3D render of the stepper driver PCB, showing the STM32 MCU, driver IC, USB-C micro connector, and boot/reset buttons

Rear side 3D render of the stepper driver PCB, showing the CAN transceiver, current-sense amplifiers, and crystal

Board revision

V1.0

Input

24 V, 2 A rated

MCU

STM32F103CBTx (Arm Cortex-M3)

Motor driver

TI DRV8844PWPR dual H-bridge, HTSSOP-16 PowerPAD

Control scheme

Field-oriented control (FOC), closed loop

Position feedback

External magnetic encoder, 4-pin differential header (J5)

Current sensing

Dual TI INA181 shunt amplifiers, one per motor phase

Bus interface

NXP TJA1051T-3 CAN transceiver

Power stage

TPS54202DDC buck converter + AMS1117 LDO for logic rails

Protection

PRTR5V0U2X ESD array, SMBJ26A TVS, PMEG6020AELR Schottky, resettable polyfuse

Programming

USB Micro-B, BOOT1 / RESET1 buttons for DFU entry

Layout

4-layer, mounted via 4x corner holes for direct NEMA17 fitment

This board is a compact closed-loop driver for a NEMA17 stepper motor, built for a robotic arm project. It runs field-oriented control on an STM32F103, reading phase current through two INA181 amplifiers and rotor position from an external magnetic encoder, so the motor can be commanded smoothly instead of driven open loop.

DRV8844 H-bridge drives both motor phases directly from the 24V rail.
Per-phase current sensing feeds the FOC control loop running on the STM32.
CAN transceiver lets the board sit on a shared bus with other joints in a multi-axis arm.
On-board buck and LDO regulators generate the 5V and 3.3V logic rails from the 24V input.
ESD and TVS protection on the CAN and USB lines for robustness outside a bench setting.
USB Micro-B plus BOOT1/RESET1 buttons for firmware flashing without a separate programmer.

FOC NEMA17 Stepper Motor Driver

Overview

Schematic & PCB

Downloads