Controller Library for Arduino Uno R4 WiFi

A beginner-friendly wireless robot controller library for the Arduino Uno R4 WiFi.

This library allows you to control a robot from a phone or computer using a built-in web interface with:

• 🕹️ Joystick control
• 🎚️ Throttle slider
• 🔘 Custom buttons
• 🛑 Built-in failsafe safety
• 💡 Status LED indicators
• 🔧 Optional L298N motor driver support

The goal is to replace fragile hardware joystick controllers with a reliable wireless interface.

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Requirements

• Arduino Uno R4 WiFi
• L298N motor driver (if using motors)
• DC motors
• Robot battery
• Phone or computer with WiFi

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Installation

Arduino IDE

1. Download the Controller zipped-library from the releases section.
2. Save the zip file to your computer.
3. Open Arduino IDE.
4. Go to:

Sketch > Include Library > Add .ZIP Library

5. Select the zip file.

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Include the Library

Add this at the top of your sketch:

#include <Controller.h>

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Basic Usage

Create the Controller

The constructor requires:

Controller controller("SSID", "password");

Example:

Controller controller("RobotAP", "12345678");

This creates a WiFi network named RobotAP.

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Start the Access Point

In setup():

void setup() {
  Serial.begin(115200);
  controller.beginAP(true);   // true = enable debug
}

• true → enables debug printing
• false → disables debug mode

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Run the Controller Loop

In loop():

void loop() {
  controller.update();
}

This is mandatory.
It handles:

• Web requests
• Joystick input
• Motor smoothing
• Failsafe safety

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Connecting to the Robot

1. Power the robot.
2. Connect your phone/laptop to the WiFi network you defined.
3. Open a browser.
4. Go to:

http://10.0.0.2

⚠️ Use http, NOT https.

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Using the L298N Motor Driver

Configure the Pins

controller.configureL298N(
  9, 7, 6,    // ENA, IN1, IN2
  10, 5, 4    // ENB, IN3, IN4
);

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Set Minimum PWM (Important)

Many motors need a minimum power level to overcome static friction.

controller.setMotorMinPWM(90);

Typical values:

Robot Type	Recommended Value
Small robot	70–90
Medium robot	90–110
Heavy robot	110–130

If motors buzz but do not move → increase this value.

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Full Motor Example

#include <Controller.h>

Controller controller("RobotAP", "12345678");

void setup() {
  Serial.begin(115200);

  controller.configureL298N(9,7,6, 10,5,4);
  controller.setMotorMinPWM(90);
  controller.setFailsafeTimeoutMs(1000);

  controller.beginAP(true);
}

void loop() {
  controller.update();
}

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Failsafe System (Safety Feature)

The failsafe ensures the robot stops if:

• The joystick is released
• The connection drops
• The browser closes
• No drive command is received within a timeout

Set timeout:

controller.setFailsafeTimeoutMs(1200);

Recommended Range

• 800–1500 ms

Smaller value → more responsive but can feel jerky
Larger value → smoother but robot continues longer if connection is lost

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Adding Buttons

You can register custom buttons in the web interface.

void onPress() {
  Serial.println("Button pressed!");
}

void setup() {
  controller.registerButton("Press Me", onPress);
}

Buttons are momentary (trigger once per press).

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Custom Drive Callback (Without L298N)

If you want to handle motor logic yourself:

void onDrive(int8_t left, int8_t right) {
  Serial.print("Left: ");
  Serial.print(left);
  Serial.print(" Right: ");
  Serial.println(right);
}

void setup() {
  controller.registerDriveCallback(onDrive);
  controller.beginAP(true);
}

left and right range from -100 to 100.

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Status LED

The onboard LED can show system states.

Enable it:

controller.enableStatusLED(LED_BUILTIN);

LED States

Pattern	Meaning
Fast blink	Booting
Slow blink	AP ready
Solid ON	Client connected
Rapid blink	Error
Double blink	Failsafe active

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Debug Mode

Enable debug:

controller.beginAP(true);

Debug prints:

• WiFi scan results
• Drive commands
• Motor values

Disable:

controller.beginAP(false);

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Important Power Note

If the robot is powered by battery and you connect USB to your computer:

⚠️ Turn the battery OFF first.

Otherwise, the board may soft-reboot or behave unexpectedly.

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Troubleshooting

Website not loading

• Make sure you're using http://
• Confirm you are connected to the robot WiFi
• Try http://10.0.0.2

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Robot stops after 1 second

Increase failsafe timeout:

controller.setFailsafeTimeoutMs(1500);

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Motors buzz but do not move

Increase minimum PWM:

controller.setMotorMinPWM(110);

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Movement feels jerky

• Increase failsafe timeout slightly
• Reduce minimum PWM
• Check battery voltage
• Ensure good WiFi signal

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PlatformIO Usage

Compile:

pio run

Upload:

platformio run -t upload

Run tests:

pio test -e uno_r4_wifi

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WiFi Status Codes (Reference)

WL_IDLE_STATUS       = 0
WL_NO_SSID_AVAIL     = 1
WL_SCAN_COMPLETED    = 2
WL_CONNECTED         = 3
WL_CONNECT_FAILED    = 4
WL_CONNECTION_LOST   = 5
WL_DISCONNECTED      = 6
WL_AP_LISTENING      = 7
WL_AP_CONNECTED      = 8

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Design Goals

This library was built to:

• Replace fragile hardware joystick controllers
• Provide a customizable wireless interface
• Ensure safety through built-in failsafe
• Allow teams to easily extend functionality
• Use the Uno R4 WiFi’s ESP32-S3 module

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Enjoy building 🚀