关于esp32蓝牙模块的使用——esp32学习笔记

关于esp32蓝牙模块的使用——esp32学习笔记

关于esp32蓝牙模块的使用——esp32学习笔记

  • 关于esp32蓝牙模块的使用——esp32学习笔记
    • 零、前言
    • 一、经典蓝牙BT
    • 二、低功耗蓝牙BLE()
      • 0.前言
      • 1.首先我们来做一些准备工作
      • 2.创建一个BLE设备
      • 3.创建一个BLE服务
      • 4.创建一个BLE特征
      • 5.开始服务和广播
      • 6.接下来呢在loop函数中我们的蓝牙连接会对应三种状态:

零、前言

esp32自带蓝牙模块可以让我们进行蓝牙连接并进行数据交换

一、经典蓝牙BT

首先来编写代码,经典蓝牙的使用非常简单,首先声明使用了BluetoothSerial这个库,然后使用SerialBT.begin函数设置蓝牙的名字,再然后就是设置配对码,由于这里没有用到配对码,所以我将注释掉。当配对成功我们就使用printf函数打印出蓝牙配对成功。

#include 
#include 

BluetoothSerial SerialBT;

void setup()
{
    Serial.begin(115200);
    SerialBT.begin("BAKUMAN"); // 如果没有参数传入则默认是蓝牙名称是: "ESP32"
    // SerialBT.setPin("1234");   // 蓝牙连接的配对码
    Serial.printf("BT initial ok and ready to pair. \r\n");
}

void loop()
{
    if (Serial.available())
    {
        SerialBT.write(Serial.read());
    }
    if (SerialBT.available())
    {
        Serial.write(SerialBT.read());
    }
    delay(1);
}

再然后就是loop函数中:

Serial.available()是串口中(演示中为电脑端)收到的信息,如果串口中有数据,就使用蓝牙发送出去。

SerialBT.available()是蓝牙中(演示中为手机端)收到的信息,如果蓝牙中有数据,就发送给串口,串口就会打印出来。

接下来就是演示的截图:

串口发送信息:

串口发送数据image-20211009160839765

蓝牙发送数据:

image-20211009160118260Screenshot_20211009_155717

二、低功耗蓝牙BLE()

0.前言

UUID:ble的服务和characteristic是通过UUID来进行识别的。创建uuid可以使用这么一个网站:Online UUID Generator Tool

notify:如果这个主机的一个特征值characteristic发生改变,就可以通过notify来告诉我们

pCharacteristic = pService->createCharacteristic(CHARACTERISTIC_UUID_TX, BLECharacteristic::PROPERTY_NOTIFY); 
//创建一个(读)特征值, 它是通知下发类型的特征值

write:我们可以把特征值定为写入类型, 这样客户端可以给我们写入, 触发写入回调函数

BLECharacteristic *pCharacteristic = pService->createCharacteristic(CHARACTERISTIC_UUID_RX, BLECharacteristic::PROPERTY_WRITE);
//创建一个(写)特征, 它是写入类型的特征值
  pCharacteristic->setCallbacks(new MyCallbacks());  
//为特征添加一个回调

使用这个低功耗蓝牙有这么几个步骤:

\1. 创建一个 BLE Server

\2. 创建一个 BLE Service

\3. 创建一个 BLE Characteristic

\4. 创建一个 BLE Descriptor

\5. 开始服务

\6. 开始广播

并且我们还需要使用BLEDevice,BLEServer,BLEUtils,BLE2902,common这几个库

1.首先我们来做一些准备工作

/*
    Video: https://www.youtube.com/watch?v=oCMOYS71NIU
    Based on Neil Kolban example for IDF: https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleNotify.cpp
    Ported to Arduino ESP32 by Evandro Copercini

   Create a BLE server that, once we receive a connection, will send periodic notifications.
   创建一个BLE服务器,一旦我们收到连接,将会周期性发送通知

   T使用步骤:
   1. 创建一个 BLE Server
   2. 创建一个 BLE Service
   3. 创建一个 BLE Characteristic
   4. 创建一个 BLE Descriptor
   5. 开始服务
   6. 开始广播


*/
#include 
#include 
#include 
#include 
#include 
#include "common.h"

uint8_t txValue = 0;                         //后面需要发送的值
BLEServer *pServer = NULL;                   //BLEServer指针 pServer
BLECharacteristic *pTxCharacteristic = NULL; //BLECharacteristic指针 pTxCharacteristic
bool deviceConnected = false;                //本次连接状态
bool oldDeviceConnected = false;             //上次连接状态

// See the following for generating UUIDs: https://www.uuidgenerator.net/
#define SERVICE_UUID "12a59900-17cc-11ec-9621-0242ac130002" // UART service UUID
#define CHARACTERISTIC_UUID_RX "12a59e0a-17cc-11ec-9621-0242ac130002"
#define CHARACTERISTIC_UUID_TX "12a5a148-17cc-11ec-9621-0242ac130002"//注意这里面是用

class MyServerCallbacks : public BLEServerCallbacks
{
    void onConnect(BLEServer *pServer)
    {
        deviceConnected = true;
    };

    void onDisconnect(BLEServer *pServer)
    {
        deviceConnected = false;
    }
};

class MyCallbacks : public BLECharacteristicCallbacks
{
    void onWrite(BLECharacteristic *pCharacteristic)
    {
        std::string rxValue = pCharacteristic->getValue(); //接收信息

        if (rxValue.length() > 0)
        { //向串口输出收到的值
            Serial.print("RX: ");
            for (int i = 0; i < rxValue.length(); i++)
                Serial.print(rxValue[i]);
            Serial.println();
        }
    }
};

2.创建一个BLE设备

	BLEDevice::init(ble_name);

3.创建一个BLE服务

    pServer = BLEDevice::createServer();
    pServer->setCallbacks(new MyServerCallbacks()); //设置回调
    BLEService *pService = pServer->createService(SERVICE_UUID);

在这里面的回调函数就是上面代码串中的MyServerCallbacks

4.创建一个BLE特征

pTxCharacteristic = pService->createCharacteristic(CHARACTERISTIC_UUID_TX, BLECharacteristic::PROPERTY_NOTIFY);
pTxCharacteristic->addDescriptor(new BLE2902());
BLECharacteristic *pRxCharacteristic = pService->createCharacteristic(CHARACTERISTIC_UUID_RX, BLECharacteristic::PROPERTY_WRITE);
pRxCharacteristic->setCallbacks(new MyCallbacks()); //设置回调

这里创建了一个特征值,类型是通知。

在后面使用createCharacteristic(CHARACTERISTIC_UUID_RX, BLECharacteristic::PROPERTY_WRITE)将rx收集到的信息写入,通过MyCallbacks再打印出来

为了实现"串口",我们在这个服务下添加了两个特征值, 一个是TX. 一个是RX.另外还需注意三个uuid因该是相对应的值。

5.开始服务和广播

    pService->start();                  // 开始服务
    pServer->getAdvertising()->start(); // 开始广播
    Serial.println(" 等待一个客户端连接,且发送通知... ");

6.接下来呢在loop函数中我们的蓝牙连接会对应三种状态:

(1)设备已经连接:

if (deviceConnected){
        pTxCharacteristic->setValue(&txValue, 1); // 设置要发送的值为1
        pTxCharacteristic->notify();              // 广播
        txValue++;                                // 指针数值自加1
        delay(2000);                              // 如果有太多包要发送,蓝牙会堵塞
    }

这里面测试的是不停发送数据,每发一次数值加一。

此时

class MyServerCallbacks : public BLEServerCallbacks
{
    void onConnect(BLEServer *pServer)
    {
        deviceConnected = true;
    };

    void onDisconnect(BLEServer *pServer)
    {
        deviceConnected = false;
    }
};

通过这个回调可以说清楚这个蓝牙到底有没有连接,如果连接了通过

pServer->setCallbacks(new MyServerCallbacks());

这个MyServerCallbacks回调就可以返回连接状态。

调式结果如图:

ble串口:

ble串口接收image-20211009210430190

ble开始广播

ble开始广播

最后附上整段代码:

/*
    Video: https://www.youtube.com/watch?v=oCMOYS71NIU
    Based on Neil Kolban example for IDF: https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleNotify.cpp
    Ported to Arduino ESP32 by Evandro Copercini

   Create a BLE server that, once we receive a connection, will send periodic notifications.
   创建一个BLE服务器,一旦我们收到连接,将会周期性发送通知

   T使用步骤:
   1. 创建一个 BLE Server
   2. 创建一个 BLE Service
   3. 创建一个 BLE Characteristic
   4. 创建一个 BLE Descriptor
   5. 开始服务
   6. 开始广播


*/
#include 
#include 
#include 
#include 
#include 
#include "common.h"

uint8_t txValue = 0;                         //后面需要发送的值
BLEServer *pServer = NULL;                   //BLEServer指针 pServer
BLECharacteristic *pTxCharacteristic = NULL; //BLECharacteristic指针 pTxCharacteristic
bool deviceConnected = false;                //本次连接状态
bool oldDeviceConnected = false;             //上次连接状态d
// See the following for generating UUIDs: https://www.uuidgenerator.net/
#define SERVICE_UUID "12a59900-17cc-11ec-9621-0242ac130002" // UART service UUID
#define CHARACTERISTIC_UUID_RX "12a59e0a-17cc-11ec-9621-0242ac130002"
#define CHARACTERISTIC_UUID_TX "12a5a148-17cc-11ec-9621-0242ac130002"

class MyServerCallbacks : public BLEServerCallbacks
{
    void onConnect(BLEServer *pServer)
    {
        deviceConnected = true;
    };

    void onDisconnect(BLEServer *pServer)
    {
        deviceConnected = false;
    }
};

class MyCallbacks : public BLECharacteristicCallbacks
{
    void onWrite(BLECharacteristic *pCharacteristic)
    {
        std::string rxValue = pCharacteristic->getValue(); //接收信息

        if (rxValue.length() > 0)
        { //向串口输出收到的值
            Serial.print("RX: ");
            for (int i = 0; i < rxValue.length(); i++)
                Serial.print(rxValue[i]);
            Serial.println();
        }
    }
};

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

    // 创建一个 BLE 设备
    BLEDevice::init("BAKUMAN");//在这里面是ble的名称

    // 创建一个 BLE 服务
    pServer = BLEDevice::createServer();
    pServer->setCallbacks(new MyServerCallbacks()); //设置回调
    BLEService *pService = pServer->createService(SERVICE_UUID);

    // 创建一个 BLE 特征
    pTxCharacteristic = pService->createCharacteristic(CHARACTERISTIC_UUID_TX, BLECharacteristic::PROPERTY_NOTIFY);
    pTxCharacteristic->addDescriptor(new BLE2902());
    BLECharacteristic *pRxCharacteristic = pService->createCharacteristic(CHARACTERISTIC_UUID_RX, BLECharacteristic::PROPERTY_WRITE);
    pRxCharacteristic->setCallbacks(new MyCallbacks()); //设置回调

    pService->start();                  // 开始服务
    pServer->getAdvertising()->start(); // 开始广播
    Serial.println(" 等待一个客户端连接,且发送通知... ");
}

void loop()
{
    // deviceConnected 已连接
    if (deviceConnected)
    {
        pTxCharacteristic->setValue(&txValue, 1); // 设置要发送的值为1
        pTxCharacteristic->notify();              // 广播
        txValue++;                                // 指针数值自加1
        delay(2000);                              // 如果有太多包要发送,蓝牙会堵塞
    }

    // disconnecting  断开连接
    if (!deviceConnected && oldDeviceConnected)
    {
        delay(500);                  // 留时间给蓝牙缓冲
        pServer->startAdvertising(); // 重新广播
        Serial.println(" 开始广播 ");
        oldDeviceConnected = deviceConnected;
    }

    // connecting  正在连接
    if (deviceConnected && !oldDeviceConnected)
    {
        // do stuff here on connecting
        oldDeviceConnected = deviceConnected;
    }
}

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