Easy Basics: Project 034a Arduino motor shield R3, one or two DC motors 3V/6V/9V

of Acoptex.com in UNO

Basics: Project 034a

Project name: Arduino motor shield R3, one or two DC motors

Tags: Arduino motor shield R3, DC motor, 3V, 6V, 9V, Arduino Uno

Attachments: oneDCmotorsketch1, twoDCmotorssketch2

Tags: Arduino, Arduino motor shield R3, DC motor

In this project, you needed these parts :

1.Aruduino Uno R3 1 pc (you can also use the other version of Arduino)

2.Arduino motor shield R3  1pc

3.Arduino IDE ( you can download it from here  )

4.Jumper cables

5. DC motor 3V/6V/9V 2 pcs

6. External motor DC power supply  1 pc


We will learn how to connect Arduino motor shield R3 to Arduino board and use it with DC motors 3V/6V/9V. 

Understanding the Arduino motor shield R3

The Arduino Motor Shield allows your Arduino board to drive DC and stepper motors, relays and solenoids.

The Arduino Motor Shield is based on the L298, which is a dual full-bridge driver designed to drive inductive loads such as relays, solenoids, DC and stepping motors. It lets you drive two DC motors with your Arduino board, controlling the speed and direction of each one independently. You can also measure the motor current absorption of each motor, among other features. The shield is TinkerKit compatible (6 headers for the attachment of Tinkerkit inputs, outputs, and communication lines), which means you can quickly create projects by plugging TinkerKit modules to the board.

By allowing you to simply address Arduino pins, the Arduino Motor Shield makes it very simple to incorporate a motor into your project. It also allows you to be able to power a motor with a separate power supply of up to 12v. 

The Motor Shield must be powered only by an external power supply. Because the L298 IC mounted on the shield has two separate power connections, one for the logic and one for the motor supply driver. The required motor current often exceeds the maximum USB current rating. External (non-USB) power can come either from an AC-to-DC adapter (wall-wart) or battery. The adapter can be connected by plugging a 2.1mm center-positive plug into the Arduino's board power jack on which the motor shield is mounted or by connecting the wires that lead the power supply to the Vin and GND screw terminals, taking care to respect the polarities. To avoid possible damage to the Arduino board on which the shield is mounted, we recommend using an external power supply that provides a voltage between 7 and 12V. If your motor require more than 9V we recommend that you separate the power lines of the shield and the Arduino board on which the shield is mounted. This is possible by cutting the "Vin Connect" jumper placed on the back side of the shield. The absolute limit for the Vin at the screw terminals is 18V.


  • Operating Voltage 5V to 12V
  • Motor controller L298P, 2 channels - drives 2 DC motors or 1 stepper motor
  • Max current 2A per channel or 4A max total (with external power supply)
  • Current sensing 1.65V/A
  • Free running stop and brake function

Understanding the DC motor

What is a stepper motor?
A digital electric motor that moves one step at a time and each step is defined by a step angle. The stepper motor moves is distinct steps during its rotation. Each steps is defined by a step angle. In the example below you may notice that there are 4 distinct steps for the rotor to make a complete 360 degree rotation. As defines in step angle at 90 degrees. Since the stepper motor does move in discreet movement, we can say that a stepper motor is actually a digital motor. This characteristic makes it very suitable for digital interfaces integrates with a microcontroller. if you want to learn more about Stepper Motor download the reference below.

Read more about it here.

Signals and connections of DC motor

To connect a motor, simply solder two wires to the MOTOR terminals and then connect them to either the Channel A (+ (red wire) and - (black wire) terminals), Channel B (+ (red wire) and - (black wire) terminals) of the Arduino motor shield R3. 

Signals and connections of Arduino motor shield R3

The power pins:

The shield can supply 2 amperes per channel, for a total of 4 amperes maximum.

Vin on the screw terminal block, is the input voltage to the motor connected to the shield. An external power supply connected to this pin also provide power to the Arduino board on which is mounted. By cutting the "Vin Connect" jumper you make this a dedicated power line for the motor.

GND Ground on the screw terminal block.

Input and output pins:

This shield has two separate channels, called A and B,

that each use 4 of the Arduino pins to drive or sense

the motor. In total there are 8 pins in use on this shield.

You can use each channel separately to drive two DC

motors or combine them to drive one unipolar stepper


The shield's pins, divided by channel are shown in the table below:

If you don't need the Brake and the Current Sensing and you also need more pins for your application you can disable this features by cutting the respective jumpers on the back side of the shield.

The additional sockets on the shield are described as follow:

  • Screw terminal to connect the motors and their power supply.
  • 2 TinkerKit connectors for two Analog Inputs (in white), connected to A2 and A3.
  • 2 TinkerKit connectors for two Aanlog Outputs (in orange in the middle), connected to PWM outputs on pins D5 and D6.
  • 2 TinkerKit connectors for the TWI interface (in white with 4 pins), one for input and the other one for output.

You can drive two DC motors by connecting the two wires of each one in the (+) and (-) screw terminals for each channel A and B. In this way you can control its direction by setting HIGH or LOW the Direction (DIR A and DIR B) pins, you can control the speed by varying the PWM A and PWM B duty cycle values. The Brake A and Brake B pins, if set HIGH, will effectively brake the DC motors rather than let them slow down by cutting the power. You can measure the current going through the DC motor by reading the Current Sensing (SNS0 and SNS1) pins. On each channel will be a voltage proportional to the measured current, which can be read as a normal analog input, through the function analogRead() on the analog input A0 and A1. For your convenience it is calibrated to be 3.3V when the channel is delivering its maximum possible current, that is 2A.


The pins of the official Arduino motor shield will only align with Arduino Uno Rev. 3. In order to make it work with older versions of the Arduino, you will need to trim a few pins off the motor shield. However, this is not, at all, recommended. Insert the motor shield pins into the socket of the Arduino Uno.

The following picture shows the needed connections with the Arduino Uno:

1. One DC motor. To control a motor using the Arduino Motor Shield R3, first plug the motor's positive (red) wire into Channel A's + terminal on the motor shield, and the motor's ground (black) wire into Channel A's - terminal on the motor shield. To connect your external power supply, connect the positive (red) wire from the power supply to the "Vin" terminal, and the ground (black) wire to the "GND" terminal.

2. Two DC motors. To control motors using the Arduino Motor Shield R3, first plug each motor's positive (red) wire into Channel A's and Channel B's + terminals on the motor shield, and each motor's ground (black) wire into Channel A's and Channel B's - terminals on the motor shield. To connect your external power supply, connect the positive (red) wire from the power supply to the "Vin" terminal, and the ground (black) wire to the "GND" terminal.

Step by Step instruction

  1. Place Arduino motor shield R3 on top of the Arduino Uno board.
  2. Do wiring.
  3. Open Arduino IDE.
  4. Plug your Adruino Uno board into your PC and select the correct board and com port
  5. Open up serial monitor and set your baud to 9600 baud
  6. Verify and upload the the sketch to your Adruino Uno


We have learnt how to connect Arduino motor shield R3 to Arduino board and use it with DC motors. 


  • No libraries required for this project.


  • See attachments on the begining of this project description.

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Published at 29-09-2017
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