# KS0378 Keyestudio Reprap Stepper Driver A4988 Kit (5PCS)

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## 1. Introduction

This stepper motor driver is powered by A4988, a DMOS microstep driver with converter and over-current protection.

It is available in full, half, 1/4, 1/8 and 1/16 stepping modes to operate bipolar stepper motor with output drive performance up to 35 V and ± 2A.

The A4988 includes a fixed turn-off time current regulator that operates in slow or mixed decay mode.

The converter is the key to implement the A4988. As long as the "step" input carries in a pulse, it can drive the motor to produce micro-step.

There is no need for phase sequence tables, high frequency control lines or complex interface programming.

The A4988 interface is ideal for complex microprocessors that are not available or overloaded.

## 2. Specifications

1. With only simple step and direction control interface;
2. Five different step modes: full, half, 1/4, 1/8 and 1/16;
3. Adjustable potentiometer can adjust the maximum current output, resulting in a higher step rate;
4. Automatic current decay mode detection / selection;
5. Overheat shutdown circuit, undervoltage lockout, cross current protection;
6. Ground short circuit protection and load short circuit protection.

## 3. Settings for working mode

![](media/wps2.jpg)

## 4. Connection Diagram

It needs to connect DC 8-15V between motor power VMOT and GND.

![](media/wps3.jpg)

## 5. Sample Code

Download code : [Code](./Code.7z)

```c
int dirPin = 7;
int stepperPin = 8;

void setup() 
{
    pinMode(dirPin, OUTPUT);
    pinMode(stepperPin, OUTPUT);
}

void step(boolean dir,int steps)
{
    digitalWrite(dirPin,dir);
    delay(50);
    for(int i=0;i<steps;i++)
    {
        digitalWrite(stepperPin, HIGH);
        delayMicroseconds(800);
        digitalWrite(stepperPin, LOW);
        delayMicroseconds(800);
    }
}

void loop()
{
    step(true,1600);
    delay(500);
    step(false,1600*5);
    delay(500);
}
```

## 6. Test Result

The selection end MS1, MS2, MS3 of three modes are all connected to GND, that is, full-step mode, and the motor needs 200 stepping values or a stepping 1.8° to turn a round. In the experiment, we first let the stepper motor reverse 8 circles and delay 0.5 seconds; then turn 40 circles and delay 0.5 seconds.

If it is an half-step mode, then the number of both positive and reverse circle should be halved.

## 7. Package Included

- Keyestudio Reprap Stepper Driver A4988 *5PCS

![](media/wps4.png)