Getting Started with RoboLink

Welcome to RoboLink

RoboLink lets you wirelessly control any ESP32 (or Arduino) robot from your Android phone. Tap a joystick, button, or slider on the app — values arrive at your board in milliseconds. You can also send sensor readings back to the app for live display.

This tutorial walks you from zero to a working connection in about 20 minutes.

Step 1: Install the App

Download RoboLink from the Google Play Store. The app is free and requires no account.

Step 2: Install the Arduino Library

First, grab the library ZIP:

• GitHub Repository — browse source, report issues
• Download ZIP directly

Then add it to Arduino IDE:

1. Open Arduino IDE and go to Sketch → Include Library → Add .ZIP Library…

2. Select the downloaded ZIP file and click Open.

3. Restart the IDE.

You should now see RoboLink under Sketch → Include Library.

Step 3: Upload the "Print All Data" Sketch

Before driving any motors, verify the connection works by printing every key-value pair the app sends.

#include <RoboLink.h>

RoboLinkWiFi robolink;

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

    // ESP32 creates a WiFi hotspot called "MyRobot"
    // Password must be at least 8 characters
    robolink.beginAP("MyRobot", "12345678");

    Serial.println("Access point started. Connect your phone to 'MyRobot'.");
}

void loop() {
    robolink.update();   // always call first — reads incoming packets

    // Print every key:value the app is sending, once per packet
    robolink.printAll(Serial);
}

Upload this to your ESP32, then open the Serial Monitor at 115200 baud.

Step 4: Connect the App

1. On your phone, go to Settings → Wi-Fi and connect to the MyRobot network (password: 12345678).
2. Open the RoboLink app.
3. Tap the connection icon and choose Wi-Fi / UDP.
4. The default port is 4210 — leave it as-is and tap Connect.

Once connected, the Serial Monitor will start printing lines like:

throttle:0,steer:0,speed:128,horn:0
throttle:45,steer:-30,speed:128,horn:0

Each line is one packet from the app at ~20 Hz.

Step 5: Read Specific Values

Once you know the key names, read individual values with get():

#include <RoboLink.h>

RoboLinkWiFi robolink;

void setup() {
    Serial.begin(115200);
    robolink.beginAP("MyRobot", "12345678");
    robolink.setTimeoutMs(500);   // safety: detect if phone disconnects
}

void loop() {
    robolink.update();

    // isTimedOut() becomes true if no packet arrives for 500 ms
    if (robolink.isTimedOut()) {
        Serial.println("No signal — stopping!");
        return;
    }

    int throttle = robolink.get("throttle");   // -100 to +100
    int steer    = robolink.get("steer");      // -100 to +100
    int speed    = robolink.get("speed");      //  0 to 255
    int horn     = robolink.get("horn");       //  0 or 1

    Serial.print("throttle="); Serial.print(throttle);
    Serial.print("  steer=");  Serial.print(steer);
    Serial.print("  speed=");  Serial.print(speed);
    Serial.print("  horn=");   Serial.println(horn);
}

Step 6: Configure the App Interface

Load a preset layout

The app ships with built-in layouts for common robot types. Tap the layout / preset button in the app menu and choose one:

After loading a preset, open the Serial Monitor running the printAll sketch — you will immediately see the correct key names arrive.

Edit a widget's key name

Every widget has a data key setting. To match your code, long-press (or tap the edit icon on) a widget:

• Joystick → set the X key and Y key fields (e.g. steer and throttle)
• Button / Toggle → set the data key field (e.g. horn)
• Slider → set the data key and the min / max range

Verify key-value pairs live

Use the built-in Serial print approach while adjusting widgets:

void loop() {
    robolink.update();
    robolink.printAll(Serial);   // prints one line per packet — watch it change as you move controls
    delay(100);                  // slow it down so the monitor stays readable
}

Move a joystick, drag a slider, or press a button — the Serial Monitor shows the value changing in real time. This makes it easy to confirm each widget is wired to the right key.

Next Steps

• WiFi Setup in depth — Station mode, credential storage, serial setup wizard
• ESP32-CAM RC Car — Add a live video stream to your robot
• Sensor data — Call robolink.setSensor("battery", 87) and robolink.setSendInterval(200) to push values back to the app's Gauge widgets