Networking & Communications

Controlling a Servo Motor with Seeed XIAO ESP32C3, LightBlue App, and Custom PCB

Introduction

In this project, I used a Seeed XIAO ESP32C3, a servo motor, the LightBlue app, and a custom PCB board to control the servo motor wirelessly. This documentation outlines the steps I took to set up and use these components together.

Components Used

• Seeed XIAO ESP32C3
• SG90 Servo Motor
• Custom PCB Board that I designed it in Electronis design week.
• Connecting wires
• Power supply (3.3V or 5V depending on the servo motor)
• LightBlue app (available on iOS and Android)

Hardware Setup

Connecting the Servo Motor to the Seeed XIAO ESP32C3

1. Signal (control) wire of the servo to GPIO pin 2 on the Seeed XIAO ESP32C3.
2. Power (Vcc) wire of the servo to the 3.3V or 5V power supply (depending on your servo's requirements).
3. Ground (GND) wire of the servo to the ground pin (GND) on the Seeed XIAO ESP32C3.

Using the Custom PCB Board

I designed a custom PCB to neatly arrange the connections and provide a robust platform for the ESP32C3 and servo motor. The PCB included headers for the ESP32C3, power lines, and connections for the servo motor.

Software Setup

Installing Necessary Libraries

1. I opened the Arduino IDE and went to Sketch > Include Library > Manage Libraries.
2. I searched for and installed the ESP32Servo library by Kevin Harrington.
3. I ensured the ESP32 board package was installed in the Arduino IDE by adding https://dl.espressif.com/dl/package_esp32_index.json to the Additional Board Manager URLs and then installing the ESP32 board package via Tools > Board > Board Manager.

Writing the Code

Here is the code I used to control the servo motor:

cpp
Copy code
#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>
#include <ESP32Servo.h>  // Include the ESP32Servo library

#define SERVICE_UUID        "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"

Servo myServo;  // Create a Servo object to control the servo
const int servoPin = 26;  // Define the pin to which the servo is connected

class MyCallbacks: public BLECharacteristicCallbacks {
    void onWrite(BLECharacteristic *pCharacteristic) {
      std::string value = pCharacteristic->getValue();

      if (value.length() > 0) {
        Serial.println("*********");
        Serial.print("New value: ");
        for (int i = 0; i < value.length(); i++)
          Serial.print(value[i]);

        Serial.println();
        Serial.println("*********");

        // Convert the received value to an integer and set the servo angle
        int angle = atoi(value.c_str());
        if (angle >= 0 && angle <= 180) {
          myServo.write(angle);
          Serial.print("Servo angle set to: ");
          Serial.println(angle);
        } else {
          Serial.println("Invalid angle received");
        }
      }
    }
};

void setup() {
  Serial.begin(115200);
  myServo.attach(servoPin);  // Attach the servo to the specified pin

  BLEDevice::init("MyESP32");
  BLEServer *pServer = BLEDevice::createServer();

  BLEService *pService = pServer->createService(SERVICE_UUID);

  BLECharacteristic *pCharacteristic = pService->createCharacteristic(
                                         CHARACTERISTIC_UUID,
                                         BLECharacteristic::PROPERTY_READ |
                                         BLECharacteristic::PROPERTY_WRITE
                                       );

  pCharacteristic->setCallbacks(new MyCallbacks());

  pCharacteristic->setValue("Hello World");
  pService->start();

  BLEAdvertising *pAdvertising = pServer->getAdvertising();
  pAdvertising->start();
}

void loop() {
  delay(2000);
}

Programming the Seeed XIAO ESP32C3

1. I connected the Seeed XIAO ESP32C3 to my computer using a USB cable.
2. In the Arduino IDE, I selected the appropriate board and port:
   • Board: XIAO_ESP32C3
   • Port: (Select the port corresponding to your ESP32C3)
3. I uploaded the code to the ESP32C3.

Using the LightBlue App

1. Connecting to My ESP32 Device:

   • I opened the LightBlue app on my smartphone.
   • I scanned for Bluetooth devices and connected to my ESP32 device, which appeared as "MyESP32".

2. Finding the Service and Characteristic:

   • Once connected, I browsed the services and characteristics.
   • I found the service with UUID 4fafc201-1fb5-459e-8fcc-c5c9c331914b.
   • Within this service, I found the characteristic with UUID beb5483e-36e1-4688-b7f5-ea07361b26a8.

3. Writing a Value to the Characteristic:

   • I selected the characteristic and chose the option to write a value.
   • I entered a numeric value (e.g., 90) as a string. This value represented the angle I wanted the servo to move to.

Testing the Setup

1. Power Up:

   • I ensured my servo and ESP32C3 were powered appropriately.
   • The ESP32C3 started advertising as "MyESP32".

2. Controlling the Servo:

   • I used the LightBlue app to connect to "MyESP32".
   • I wrote a desired angle value to the characteristic.
   • The servo moved to the specified angle.

Troubleshooting

• Servo Not Moving:

  • I ensured the servo was connected correctly and receiving adequate power.
  • I verified that the ESP32C3 was powered and running the code correctly.
  • I checked the serial monitor for any error messages.

• Bluetooth Connection Issues:

  • I ensured the ESP32C3 was advertising as "MyESP32".
  • I restarted the LightBlue app and tried reconnecting.

By following these steps, I was able to control a servo motor using the Seeed XIAO ESP32C3, the LightBlue app, and a custom PCB. This setup allows for wireless control of the servo, enabling various applications such as robotics, remote control systems, and more.