ESP32 S3 UNO - DC Motor Shield

Hardware Preparation

Or you can buy the following kits:

Motor Shield Rev3 Overview

Before you write any code, it helps to know which pin does what on the shield. Every motor channel uses four pins, and the code must point to the right GPIO numbers.

The main chip on the Motor Shield Rev3 is the L298P dual full-bridge driver. It controls two DC motors on their own. Each motor channel has a direction line, a PWM speed line, a brake line, and a current-sensing output.

Direction

This is a digital output. HIGH spins the motor one way, and LOW spins it the other way.

PWM (Speed)

This is a PWM output. The value goes from 0 (stopped) to 255 (full speed).

Brake

This is a digital output. HIGH locks the motor shaft. LOW lets the motor turn freely.

Current Sensing

This is an analog signal that goes back into the ESP32 S3 Uno. Its voltage rises when the motor draws more current.

The ESP32 S3 Uno uses the same header positions as a classic Uno, so the shield pins land on these ESP32 S3 Uno pins:

Powering the Motors

A DC motor needs more current than the USB port can give. Connect a 6-12V external supply (for example two 18650 lithium cells in series) to the power screw terminals of the shield. The ESP32 S3 Uno can still run from USB.

ESP32 S3 Uno Pinout

The image below shows the pinout of the ESP32 S3 Uno form board. Use it to see which GPIO sits under each Uno header pin that the shield uses.

Wiring Diagram

There are no jumper wires for the control signals. You just stack the shield and connect the motor and the battery to the screw terminals.

1. Push the Motor Shield Rev3 onto the ESP32 S3 Uno headers. Check that every pin goes in fully.
2. Connect the two DC motor wires to the Channel A screw terminals. The channel names are printed on the shield.
3. Connect the external battery pack to the power screw terminals.

This image is created using Fritzing. Click to enlarge image

How to Install the Library

The DIYables_DC_Motor library hides the pin details and gives you simple functions like run() and brake(). You only need to install it once.

1. Connect the ESP32 S3 Uno to your computer with a USB Type-C cable.
2. Open the Arduino IDE and select the ESP32S3 Dev Module board and the correct COM port.
3. Click the Libraries icon on the left side.
4. Type "DIYables_DC_Motor" in the search box and find the library by DIYables.
5. Click Install.

• Search for DIYables_DC_Motor created by DIYables.io and click the Install button.

The library has no other dependencies, so nothing else needs to be installed.

Minimal Sketch Structure

Every motor sketch in this tutorial follows the same small pattern. Once you know it, the longer examples are easy to read.

The call to motor.begin() sets up the direction, PWM and brake pins. Then motor.run() sets the direction, releases the brake and applies the speed you ask for. Finally, motor.brake() locks the motor and sets the PWM to zero.

Single Motor on Channel A

This first full example is the best place to check that your shield, motor and battery all work. The motor turns forward, stops, turns backward, and stops again, every two seconds.

How to Run

1. New to the ESP32 S3 Uno? Follow ESP32 S3 Uno - Getting Started first.
2. Wire it up: stack the shield and connect the motor to Channel A.
3. Connect the battery pack to the power screw terminals.
4. Connect the board to your computer with a USB Type-C cable.
5. Open Arduino IDE, choose the ESP32S3 Dev Module board and the correct COM port.
6. Copy the code above and paste it into the Arduino IDE.
7. Upload the code by clicking the Upload button.
8. Open the Serial Monitor at 9600 baud to see the direction changes.
9. Tip: if the motor only hums and does not turn, raise the speed value from 30 to 80 or more.

The motor switches between forward and backward at speed 30, with a 2-second stop between each change.

Method Quick Reference

Single Motor on Channel B

The second channel works in exactly the same way. Only the pin numbers in the constructor change.

How to Run

1. Move the motor wires to the Channel B screw terminals.
2. Upload the sketch and open the Serial Monitor.

The motor behaves just like on Channel A. The difference is only the pins: D13 (GPIO12), D11 (GPIO11), D8 (GPIO21) and A1 (GPIO1).

Two Motors - Both Channels

With two motors you can build a small robot car. This sketch shows the three basic moves: both forward, both backward, and one forward with one backward (turning on the spot).

How to Run

1. Connect one motor to Channel A and the other motor to Channel B.
2. Upload the sketch and open the Serial Monitor.

The sketch repeats the three moves with a short brake between each one.

Reading Motor Current

Reading the current tells you how hard the motor is working. A sudden jump often means the motor is stalled or blocked.

The sketch runs the motor forward at speed 100 and prints the raw current reading every 500 ms. The line analogSetAttenuation(ADC_11db) in setup() is important. By default, the ESP32 S3 Uno ADC can only measure a small voltage. The 11 dB setting lets the analog pin read the full range, from 0V up to about 3.3V. Without it, readings reach 4095 too early and the current values look wrong.

How to Run

1. Connect a motor to Channel A.
2. Upload the sketch and open the Serial Monitor.
3. Watch the value, which updates every 500 ms. Gently slow the motor shaft with your fingers and the number goes up.

About Current Sensing

Pins A0 (GPIO2) and A1 (GPIO1) carry a voltage that grows with the current of Channel A and Channel B. The shield gives about 1.65V per amp. The readCurrent() function returns the raw ADC value. On the ESP32 S3 Uno this is a 12-bit number from 0 to 4095, where 4095 is about 3.3V. To get a rough current in milliamps, use: current (mA) = raw × 3300 / 4095 / 1.65. For example, a reading of 410 is about 330mV, which is about 200mA. The ESP32 S3 Uno ADC is not perfectly linear, so treat this as an estimate.

Custom Pin Assignment

You can also give your own pin numbers to the constructor. This is useful if you use a different motor driver board, or if you want to move a signal to another pin.

How to Run

1. Change the pin numbers in the constructor to match your hardware. Always write the GPIO number (for example 13), not the header label (D12).
2. Upload the code and check that the motor runs as expected.

Quick Motor Checks

These are the first things to check when the motor does not behave as you expect. The full Troubleshooting table at the end of the page covers more cases.

Motor does not move

Check that the motor wires sit tightly in the screw terminals. Also check that the motor channel matches the pins in your code. Channel A uses 13, 17, 46, 2 and Channel B uses 12, 11, 21, 1.

Motor hums but has no torque

Raise the speed value. A very low PWM value may not be enough to start the motor.

External supply is dead

Charge or replace the batteries, and check the polarity at the power terminals.

Direction is reversed

Swap the two motor wires at the screw terminal, or swap MOTOR_FORWARD and MOTOR_BACKWARD in the code.

Current reading is always zero

Use the 4-pin constructor that includes the current-sensing pin, such as motor(13, 17, 46, 2). The 3-pin constructor has no current-sensing pin.

ESP32 S3 Uno DC Motor Shield - Full Demo

Watch the video below to see this ESP32 S3 Uno project step by step.

Platform Support

The library uses only standard Arduino functions (pinMode, digitalWrite, analogWrite, analogRead), so it runs on the ESP32 S3 Uno with the esp32 by Espressif Systems core. The only thing you must change is the constructor: pass the GPIO numbers instead of MOTOR_CH_A or MOTOR_CH_B, because those shortcuts hold classic Uno pin numbers.

FAQ

Can I use the Motor Shield Rev3 on the ESP32 S3 Uno?

Yes. The ESP32 S3 Uno has the Uno header layout, so the shield plugs in directly. The board sends 3.3V control signals to the shield, which the L298P driver reads as HIGH. The only signals coming back are the current-sensing voltages, and they stay under 3.3V.

Why can't I use MOTOR_CH_A and MOTOR_CH_B on the ESP32 S3 Uno?

These shortcuts store classic Uno pin numbers such as 12, 3 and 9. On the ESP32 S3 Uno, code uses GPIO numbers, and GPIO12, GPIO3 and GPIO9 are not under D12, D3 and D9. Use motor(13, 17, 46, 2) for Channel A and motor(12, 11, 21, 1) for Channel B instead.

Why does the current sensing code call analogSetAttenuation(ADC_11db)?

It sets the ESP32 S3 Uno ADC input range to about 0-3.3V, so the full current-sensing signal maps to 0-4095. Without it the range is smaller and readings saturate early. The UNO R4 does not need this line, because it is ESP32-only. The shield output stays at 3.3V or less up to 2A per channel.

Is D9 (GPIO46) safe to use for the brake pin?

It works in most cases. GPIO46 is a boot strapping pin, so the board checks it at power-up. If the board will not boot or upload with the shield on, take the shield off, upload, then put it back. You could also cut the brake trace and use a free pin, but then the brake would need a jumper wire.

Can I power the motors from the ESP32 S3 Uno 5V pin?

It is not a good idea. Motors draw high current and create electrical noise, which can reset the board. Use an external 6-12V supply on the shield's power terminals, and keep the board on USB.

What if my robot needs more pins than the Uno headers give?

The ESP32 S3 Uno has two extra rows of holes with more GPIOs: GPIO15 and GPIO16 (I/O, PWM, analog), GPIO45 and GPIO35 to GPIO42 (I/O, PWM), and GPIO47/GPIO48 (output only, PWM). Solder pin headers to use them and write the GPIO number in code. With the motor shield on, they are handy for extra parts: GPIO15/GPIO16 for analog sensors, and GPIO35 to GPIO42 for buttons or ultrasonic sensors. Do not use GPIO47/GPIO48 for inputs. Be careful with two things. First, GPIO47/GPIO48 may run at 1.8V instead of 3.3V on some modules (especially ones with "V" in the name, like R8V or R16V), so 3.3V devices can be damaged or act strangely. Second, GPIO0, GPIO3 (D6), GPIO45 and GPIO46 (D9) are boot strapping pins, and a wrong connection can stop the board from booting or uploading code. Use the other extra pins first.

Troubleshooting

Learn More

• ESP32 S3 UNO - Servo Motor