Stepper UNO v1.0

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StepperUNO - Stepper Motor Manual Control


The StepperUNO is a stepper motor manual control board for standalone system.

It can control up to two stepper motors and read sensors at the same time. It is suitable for small application requiring manual control and automation.

Based on the pattern of the Arduino UNO it is designed to host a LCD keypad shield. This combination makes the stepperUNO an excellent board for application control.

This is programmed using Arduino IDE. Sketch can be uploaded directly from USB port.

Link to the shop


- 2 Motor control output (Generic or embedded A4988 drivers)
- 4 Digital Input/Output
- 2 Analog Input (can be used as digital I/O)
- 1 USB port
- 1 Power port (2.1mm Jack)
- 1 Potentiometer control
- 6 push buttons.
- 16x2 LCD screen

Motor Driver options

The stepperUNO was designed to communicate with any stepper driver.

The product offers two variants.

  • A embedded A4988 driver option and
  • A generic screw terminal connector for interfacing with an external driver.

Both options are available at purchase time.

Generic connector

Generic Driver

With this configuration it is possible to connect any external driver to the stepperUNO. The connector is a screw terminal block for V+ Ground Step Direction and Enable. For example units that can be interfaced this way might be Geckodrive / Sanyo Denki 3 / TB6600 / TB6560 etc.

The connections are as follow

Gnd V+ Gnd EN 2 Step 2 Dir 2 Gnd V+ Gnd EN 1 Step 1 Dir 1

Note Gnd's are connected together. So as the V+'s. V+ can serve as input to power up the StepperUNO from an external PSU.

A4988 driver

A4988 driver

The A4988 driver can be fitted on the StepperUNO itself. The motor is then connected directly to the StepperUNO using the 4 pin connector.

Microstepping. The A4988 can be microstepped by soldering together the jumper pads at the back of the circuit board. A4988 driver

Instead of the A4988 other driver such as the DRV8825 and TMC S2225 can also be used.

Motor Control

The step forward with the StepperUNO is the addition of dedicated Attiny85 microcontroller for each motor. Thus allowing the main microcontroller (arduino UNO) to perform other tasks while the motor are in action. Motor control operation will not interfere with other programmed task (e.g. LCD / sensor reading / compuation/ etc...). This also allows for smooth operation of the motors (e.g. preventing the motor rattle while the mcu is sending data to print on the screen).

The ATtiny85 communicates with the main Atmega328 MCU via i2c. All controls can be easily used using the StepperUNO library.

See also Update attiny firmware on StepperUNO

User Control / Manual Control

The well known LCD keypad shield is used. It uses the usual LiquidCrystal library to display informations.

From the LCD keypad six push buttons are available. We have rerouted the reset button as a normal function button. The StepperUNO library contains functions to program them easily.

The potentiometer is available for linear controls such as speed.


All digital and analog ports are available with screw terminal connectors. On each port there are three pins. Data/Ground and +5V. Ground and +5v are here for powering the sensor.

The Digital Input/Outputs available are:

The analog Inputs available are
The analog input can be used a s Digital I/O. Making 6 DIO available. These would be


To connect a microswitch to one of the DIO the pin out should be as such
Vcc -> NO
Gnd -> NC
In -> Common

Power supply

The stepper UNO can be powered using a conventional 12V PSU with 2.1mm jack connector.

With A4988 driver the power to the motor is provided directly by the 12V power supply.

With the generic driver is it recommended to use a separate power supply for the motor. This later must be connected directly to the external driver. Using the power from the stepperUNO (Gnd and V+) to feed the motors can used for small motors only.


The full combo StepperUNO/keypad shield can sit in a basket enclosure. This can be mounted on aluminium profile or other support.


The stepperUNO library is available in the section Files below.

The library is described in more details in

StepperUNO Library 1.4
StepperUNO Library 1.5

For older version (1.3 and below) see StepperUNO Library 1.1.

A simple usage example is shown below.

// simpledrive v1.3
// Example usage of stepperUNO library
// drive a single motor with left/right button

// library: stepperUNO_v1.4

#define Pot 3 // Potentiometer is on pin 3

#include <LiquidCrystal.h>
#include <stepperUNO.h>

LiquidCrystal lcd(8, 9, 4, 5, 6, 7);
keypad Keypad;
stepMOTOR motor1;

const int Nstep = 200; // Enter here the number of step/rev for your motor

void setup() {

  motor1.begin(0x4, Nstep); // Motor 1 is at address 0x5. Motor 2 on 0x4

  lcd.begin(16, 2); // LCD initialisation


void loop() {

  int POTval = analogRead(Pot);
  int rpm = map(POTval, 0, 1023, 5, 500); // Speed range from 5 to 500rpm


  if (Keypad.state == PRESSED_RIGHT) {
    lcd.setCursor(0, 0);
    Keypad.closeEvent(); // Must be here to indicate we are done with the event 
  else if (Keypad.state == PRESSED_LEFT) {
    lcd.setCursor(0, 0);
    lcd.print("LEFT ");

  else if ( Keypad.state == RELEASED_RIGHT ) {
    lcd.setCursor(0, 0);
  else if ( Keypad.state == RELEASED_LEFT ) {
    lcd.setCursor(0, 0);

}//end loop


StepperUNO Library v1.2
StepperUNO Library v1.3
StepperUNO Library v1.4
StepperUNO Library v1.4.1
StepperUNO Library v1.5.0

To install the library download the above zip file. In Arduino IDE go to Sketch | Include Library | Add .ZIP Library. Then select the downloaded zip file.

Version 1.4 -> If you have acquired the stepperUNO before 1st March 2021 you will need to reflash the 2 attiny85 to use this version.

Application Examples

The library is provided with several examples in the Example directory.