我需要一个划船机蓝牙作为从机，连接手机app和手柄这两个主机的蓝牙配置例程

以下是一个简单的划船机蓝牙从机连接手机app和手柄主机的配置例程：

#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>

BLEServer* pServer = NULL;
BLECharacteristic* pCharacteristic = NULL;

// 定义手柄和手机app主机的UUID
#define HANDSET_UUID "0000fff0-0000-1000-8000-00805f9b34fb"
#define APP_UUID "0000fff1-0000-1000-8000-00805f9b34fb"

// 定义手柄和手机app主机的特征值
uint8_t handsetValue[20] = {0};
uint8_t appValue[20] = {0};

// 划船机蓝牙从机的回调函数
class MyServerCallbacks: public BLEServerCallbacks {
    void onConnect(BLEServer* pServer) {
      // 连接成功后初始化特征值
      pCharacteristic->setValue(handsetValue, 20);
      pCharacteristic->notify();
    }

    void onDisconnect(BLEServer* pServer) {
      // 断开连接后清空特征值
      memset(handsetValue, 0, 20);
    }
};

// 手柄主机的回调函数
class HandsetCallbacks: public BLECharacteristicCallbacks {
    void onWrite(BLECharacteristic *pCharacteristic) {
      // 接收手柄主机的数据并更新特征值
      std::string value = pCharacteristic->getValue();
      memcpy(handsetValue, value.c_str(), value.length());
    }
};

// 手机app主机的回调函数
class AppCallbacks: public BLECharacteristicCallbacks {
    void onWrite(BLECharacteristic *pCharacteristic) {
      // 接收手机app主机的数据并更新特征值
      std::string value = pCharacteristic->getValue();
      memcpy(appValue, value.c_str(), value.length());
    }
};

void setup() {
  BLEDevice::init("RowingMachine");
  pServer = BLEDevice::createServer();
  pServer->setCallbacks(new MyServerCallbacks());

  // 添加手柄主机的特征值
  BLEService* pHandsetService = pServer->createService(BLEUUID(HANDSET_UUID));
  pCharacteristic = pHandsetService->createCharacteristic(
                      BLEUUID(HANDSET_UUID),
                      BLECharacteristic::PROPERTY_READ |
                      BLECharacteristic::PROPERTY_WRITE |
                      BLECharacteristic::PROPERTY_NOTIFY
                    );
  pCharacteristic->setCallbacks(new HandsetCallbacks());

  // 添加手机app主机的特征值
  BLEService* pAppService = pServer->createService(BLEUUID(APP_UUID));
  pCharacteristic = pAppService->createCharacteristic(
                      BLEUUID(APP_UUID),
                      BLECharacteristic::PROPERTY_READ |
                      BLECharacteristic::PROPERTY_WRITE |
                      BLECharacteristic::PROPERTY_NOTIFY
                    );
  pCharacteristic->setCallbacks(new AppCallbacks());

  // 开始广播
  pHandsetService->start();
  pAppService->start();
  BLEAdvertising* pAdvertising = pServer->getAdvertising();
  pAdvertising->start();
}

void loop() {
  // 定时更新特征值
  pCharacteristic->setValue(handsetValue, 20);
  pCharacteristic->notify();
  delay(10);
}

在上述代码中，我们使用了ESP32 BLE库来实现划船机蓝牙从机的功能。首先，在`setup()`函数中初始化BLE设备并创建BLE server，然后添加手柄主机和手机app主机的服务和特征值，并设置回调函数。在`loop()`函数中定时更新特征值。在手柄主机和手机app主机连接到从机时，会触发`onConnect()`回调函数，我们可以在该函数中初始化特征值。当手柄主机或手机app主机发送数据到从机时，会触发相应的回调函数，我们可以在回调函数中接收数据并更新特征值。当手柄主机或手机app主机断开连接时，会触发`onDisconnect()`回调函数，我们可以在该函数中清空特征值。