SparkFun's Experimental SparkX Qwiic Step Aims to Make Stepper Motor Control as Easy as Pie

Supporting headless operation, multiple interrupts including an emergency stop, and support for 2A motors, the Qwiic Step is impressive.

SparkFun has launched another experimental SparkX board design, offering stepper motor control on a Qwiic-compatible I2C bus — complete with built-in support for an emergency stop button and the ability to drive motors requiring up to 2A.

The Qwiic Step is SparkFun's latest entry in the SparkX board family, a range of experimental designs sold as fully-operational devices but without the guarantee that they'll become a regularly-produced line in the company's range, following the release of the Qwiic GPIO add-on board and BlackBoard C Arduino-compatible development board earlier this month. Like the Qwiic GPIO, the Qwiic Step is designed to bring additional functionality to a microcontroller's I2C bus: Simple control of stepper motors.

"Ever found controlling stepper motors confusing? There are a huge variety of wires to get connected right: power, motor coils, and control lines," the company explains of the reason for the board's existence. "And the tiny screwdriver to adjust the terminals is never where it should be. Qwiic Step simplifies the tangle. Just connect your motor to Qwiic Step using the ergonomic latch terminals, apply 8 - 35V to the barrel jack, and plug in Qwiic Step to your favourite RedBoard with a Qwiic cable.

"Qwiic Step comes preprogrammed to accept simple I2C commands, handling all the complex stepper motor calculations and control.This firmware leverages the AccelStepper library to fine tune each step of the motor. The speed, acceleration, position, and micro-step mode can be configured by the user. Additionally, the hold and run voltage of the motor is adjustable. This allows the user to specify maximum hold and run currents."

The Qwiic Step is based on the A4988 stepper motor driver, supporting motors up to 2A with power supplied via barrel-jack or a latching two-pin terminal. Heat is sunk through a large ground plane, with the option to add heatsinks — not supplied — if required. The design includes support for open-drain bussed limit switches and an emergency stop button, offers a range of interrupt options, and can run entirely standalone: Once programmed, the Qwiic Step can replay commands automatically at power-on.

The SparkX Qwiic Step is now available, priced at $34.95, from the SparkFun store.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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