ShiftStick

Description

ShiftStick: External Stepper Driver Interface

Designed by Howard Dutton | The Professional Link for OnStep & CNC

The ShiftStick is a specialized interface module designed to replace standard “Pololu-style” stepper drivers. Rather than driving a motor directly, it acts as a high-speed buffer, converting low-voltage microcontroller signals into robust 5V TTL outputs. This allows your OnStep or CNC controller to command large, external industrial stepper or servo drivers with rock-solid reliability.

The OnStep Standard

Developed by Howard Dutton (the creator of OnStep), the ShiftStick is the gold standard for moving beyond integrated drivers. It uses a 74HCT245 buffer to provide the current necessary to drive the optocouplers found in most industrial “Common Cathode” drivers.

Project Source: You can find the original open-source design and documentation at Howard Dutton’s OSHWLab Project Page.

Key Features:

• Plug-and-Play Integration: Designed to fit standard driver sockets on OnStep and CNC shield-style boards.

• Optimized Startup: Custom pull-up/down configurations prevent “motor jump” during controller boot-up, specifically tested for ESP32 and other modern hardware.

• Fault Monitoring: Includes a dedicated FLT (Fault) input to monitor driver health and an M2 output for digital gearing or micro-step switching.

Power & Voltage Specs:

The ShiftStick offers two flexible power configurations:

1. Regulated Mode: Use the onboard AMS1117-5V regulator to power the module directly from your motor rail. Maximum $V_{mot}$ is 15V for this configuration.

2. External Mode: For high-voltage systems (24V+), the regulator can be bypassed to use a 5V source from your mainboard or an external buck converter.

Take your DIY telescope mount or CNC project to the industrial level with the ShiftStick.