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Bluetooth Usage

Seeed Studio XIAO ESP32C3 supports Bluetooth 5 (LE) connectivity. This wiki will introduce the basics of Bluetooth usage on this board.

Hardware set up‚Äč

  • Step 1. Connect the included WiFi/ Bluetooth antenna to the IPEX connector on the board
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  • Step 2. Connect XIAO ESP32C3 to your computer via a USB Type-C cable
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Scan Bluetooth devices‚Äč

In this example, we are going to use XIAO ESP32C3 to scan available Bluetooth devices around it.

  • Step 1. Copy and paste the code below into Arduino IDE
#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEScan.h>
#include <BLEAdvertisedDevice.h>

int scanTime = 5; //In seconds
BLEScan* pBLEScan;

class MyAdvertisedDeviceCallbacks: public BLEAdvertisedDeviceCallbacks {
void onResult(BLEAdvertisedDevice advertisedDevice) {
Serial.printf("Advertised Device: %s \n", advertisedDevice.toString().c_str());
}
};

void setup() {
Serial.begin(115200);
Serial.println("Scanning...");

BLEDevice::init("");
pBLEScan = BLEDevice::getScan(); //create new scan
pBLEScan->setAdvertisedDeviceCallbacks(new MyAdvertisedDeviceCallbacks());
pBLEScan->setActiveScan(true); //active scan uses more power, but get results faster
pBLEScan->setInterval(100);
pBLEScan->setWindow(99); // less or equal setInterval value
}

void loop() {
// put your main code here, to run repeatedly:
BLEScanResults foundDevices = pBLEScan->start(scanTime, false);
Serial.print("Devices found: ");
Serial.println(foundDevices.getCount());
Serial.println("Scan done!");
pBLEScan->clearResults(); // delete results fromBLEScan buffer to release memory
delay(2000);
}

Step 2. Upload the codes and open the Serial Monitor to start scanning for Bluetooth devices

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XIAO ESP32C3 as Bluetooth server‚Äč

In this example, we are going to use XIAO ESP32C3 as a Bluetooth server. Here we will search for XIAO ESP32C3 board using a smartphone and send out strings to display on the serial monitor

  • Step 1. Copy and paste the code below into Arduino IDE
#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>

// See the following for generating UUIDs:
// https://www.uuidgenerator.net/

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


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("*********");
}
}
};

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

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() {
// put your main code here, to run repeatedly:
delay(2000);
}
  • Step 2. Upload the codes and open the Serial Monitor

  • Step 3. Download and install LightBlue App on your smartphone

  • Step 4. Open Bluetooth on your phone, bring the phone close to XIAO ESP32C3, scan for devices and connect with MyESP32 device
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  • Step 5. Open the LightBlue app and click Bonded tab
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  • Step 6. Click CONNECT next to MyESP32
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  • Step 7. Click the section at the very bottom which says Readable, Writable
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  • Step 8. Under Data format drop-down menu, select UTF-8 String
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  • Step 9. Type "Hello" under WRITTEN VALUES and click WRITE
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You will see the text string "Hello" output on the serial monitor of Arduino IDE

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