# BigTreeTech S42C V1.0 Closed Loop Stepper Driver

> NEMA 17 (42mm) stepper motor closed-loop driver board with OLED display. Uses encoder feedback to eliminate missed steps and improve high-speed 3D printer and CNC motor performance.

## Quick Facts

- **Brand:** BigTreeTech
- **Board Type:** motor-driver
- **Price:** ~$19.86
- **Product Readiness:** consumer
- **CPU:** STM32F103C8T6
- **CPU Architecture:** ARM Cortex-M3 32-bit
- **CPU Cores:** 1
- **RAM:** 20KB
- **Flash:** 64KB
- **USB:** No
- **Power:** DC 12-24V via motor supply
- **Operating Voltage:** 3.3V
- **SD Card:** No

## Open Source

- **Firmware:** Yes
- **Schematics:** Yes
- **PCB Layout:** Yes

## Compatible Firmware

Marlin, Klipper, RepRapFirmware

## Use Cases

- 3d-printer
- cnc
- closed-loop-motion
- stepper-control

## Components

- **OLED Display** (display): Small OLED display for real-time motor status, encoder feedback, and configuration — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fcdn-shop.adafruit.com%2Fdatasheets%2FSSD1306.pdf&ref=openhardware.directory&product=bigtreetech-s42c-v1-0-closed-loop-stepper-driver&source=md-export)
- **Magnetic Rotary Encoder** (encoder): High-speed magnetic rotary position sensor for closed-loop motor feedback — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fams.com%2Fdocuments%2F20143%2F36005%2FAS5047P_DS000324_3-00.pdf&ref=openhardware.directory&product=bigtreetech-s42c-v1-0-closed-loop-stepper-driver&source=md-export)

## Protocols

- **STEP/DIR/EN**
- **UART**
- **I2C**

## Description

The BigTreeTech S42C V1.0 is a closed-loop stepper motor driver board designed for NEMA 17 (42mm) stepper motors. Unlike traditional open-loop stepper drivers, the S42C uses an encoder to continuously monitor the motor's actual position, comparing it against the commanded position and compensating for any error in real time.

This closed-loop control eliminates the root cause of print failures from missed steps — a common problem at high speeds or when the motor is under heavy load. The board includes an integrated OLED display that shows real-time motor status, encoder feedback data, and configuration parameters.

The S42C connects inline between a standard stepper driver output and the motor, making it compatible with virtually any 3D printer mainboard. It supports STEP/DIR/EN interface, meaning no firmware changes are needed on the host controller. The board is fully open source with firmware and hardware files available on GitHub.

## Where to Buy

- [BIQU Equipment](https://openhardware.directory/r?to=https%3A%2F%2Fbiqu.equipment%2Fproducts%2Fbigtreetech-s42c-v1-0-42-stepper-motor-closed-loop-driver-board-with-oled-display&ref=openhardware.directory&product=bigtreetech-s42c-v1-0-closed-loop-stepper-driver&source=md-export) — $19.86

## Resources

- [github](https://openhardware.directory/r?to=https%3A%2F%2Fgithub.com%2Fbigtreetech%2FBIGTREETECH-S42B-V1.0&ref=openhardware.directory&product=bigtreetech-s42c-v1-0-closed-loop-stepper-driver&source=md-export)
- [product](https://openhardware.directory/r?to=https%3A%2F%2Fbiqu.equipment%2Fproducts%2Fbigtreetech-s42c-v1-0-42-stepper-motor-closed-loop-driver-board-with-oled-display&ref=openhardware.directory&product=bigtreetech-s42c-v1-0-closed-loop-stepper-driver&source=md-export)

## Tags

`stepper-driver`, `closed-loop`, `nema17`, `oled`, `3d-printer`, `cnc`, `bigtreetech`, `open-source`, `encoder`

## Images

![BigTreeTech S42C V1.0 Closed Loop Stepper Driver](https://nbg1.your-objectstorage.com/openhardware-directory/entities/bigtreetech-s42c-v1-0-closed-loop-stepper-driver/d0340e1bcee2.jpg)
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![BigTreeTech S42C V1.0 Closed Loop Stepper Driver](https://nbg1.your-objectstorage.com/openhardware-directory/entities/bigtreetech-s42c-v1-0-closed-loop-stepper-driver/0a6c0af25c07.jpg)

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