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 <Arduino.h>
#include <BluetoothSerial.h>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：

蓝牙发送数据：

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=oCMOYS71NIUBased on Neil Kolban example for IDF: https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleNotify.cppPorted to Arduino ESP32 by Evandro CoperciniCreate 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 Server2. 创建一个 BLE Service3. 创建一个 BLE Characteristic4. 创建一个 BLE Descriptor5. 开始服务6. 开始广播*/
#include <Arduino.h>
#include <BLEDevice.h>
#include <BLEServer.h>
#include <BLEUtils.h>
#include <BLE2902.h>
#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1pTxCharacteristic->notify();              // 广播txValue++;                                // 指针数值自加1delay(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开始广播

最后附上整段代码：

/*Video: https://www.youtube.com/watch?v=oCMOYS71NIUBased on Neil Kolban example for IDF: https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleNotify.cppPorted to Arduino ESP32 by Evandro CoperciniCreate 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 Server2. 创建一个 BLE Service3. 创建一个 BLE Characteristic4. 创建一个 BLE Descriptor5. 开始服务6. 开始广播*/
#include <Arduino.h>
#include <BLEDevice.h>
#include <BLEServer.h>
#include <BLEUtils.h>
#include <BLE2902.h>
#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1pTxCharacteristic->notify();              // 广播txValue++;                                // 指针数值自加1delay(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 connectingoldDeviceConnected = deviceConnected;}
}