Lesson 17

App Remote Control (Hiwonder 6.10)

🤖 Second Semester Begins - Remote Control to Vision

🎯 Learning Objectives

• Connect miniAuto to a phone/tablet using the official app remote control workflow
• Understand the difference between the app (UI) and the robot firmware (what actually drives motors)
• Practice safe remote driving (speed limiting, emergency stop, connection-loss behavior)
• Learn a clean “command protocol” pattern (single-character commands like F/B/L/R/S)
• Verify and troubleshoot common connection problems (pairing, serial conflicts, power)

📱 Section 1: What “App Control” Really Means

The phone app is just a remote “controller UI”. The robot still needs firmware on the Arduino to: (1) read incoming commands (Bluetooth/WiFi serial data), and (2) translate those commands into motor actions.

A Simple Command Protocol

// Example command set (keep it small and reliable)
// F = forward
// B = backward
// L = left
// R = right
// S = stop (always supported)
// 0-9 = optional speed presets
//

// The app sends commands.
// Arduino reads them from Serial (or SoftwareSerial).
// Arduino controls motors based on the command.

🔗 Section 2: Connection + Pairing Checklist

Before You Start

• Power: Robot battery is charged and switch is ON
• Bluetooth module: Installed firmly (correct orientation)
• Upload safety: Remove Bluetooth module when uploading sketches (prevents serial conflicts)
• Phone Bluetooth: Enabled, and robot is discoverable/pairable

What You Should See

• Bluetooth LED: Usually blinks fast when not connected, slower/steady when connected
• App status: Shows connected device (or a connect button)

📲 Section 2.5: Install the Hiwonder Control App

In the Google Play Store, search for Hiwonder. Install the app named Wonderbot (Publisher: Hiwonder).

1. Open the Google Play Store
2. Search Hiwonder
3. Install Wonderbot (Hiwonder • Tools)
4. Turn on Bluetooth on your phone/tablet
5. Power on the robot and connect inside the app

🧯 Section 3: Arduino Side - Reading Commands Safely

App control is only as safe as your firmware. Your robot should always: (1) have a STOP command, (2) stop when no commands are received for a timeout, and (3) clamp speed.

Command Handling Pattern

// Pseudocode structure
unsigned long lastCommandMs = 0;
const unsigned long COMMAND_TIMEOUT_MS = 500; // stop if no command for 0.5s

void loop() {
  if (Serial.available()) {
    char cmd = (char)Serial.read();
    lastCommandMs = millis();
    handleCommand(cmd);
  }

  if (millis() - lastCommandMs > COMMAND_TIMEOUT_MS) {
    stopMotors();
  }
}

void handleCommand(char cmd) {
  switch (cmd) {
    case 'F': moveForward(); break;
    case 'B': moveBackward(); break;
    case 'L': turnLeft(); break;
    case 'R': turnRight(); break;
    case 'S': stopMotors(); break;
  }
}