Sending Sensor Data via Bluetooth

/*
Based on Neil Kolban example for IDF: https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleServer.cpp
Ported to Arduino ESP32 by Evandro Copercini
updates by chegewara
*/

#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>
#include <Wire.h>                 // Must include Wire library for I2C
    #include <SparkFun_KX13X.h> // Click here to get the library: http://librarymanager/All#SparkFun_KX13X

SparkFun_KX132 kxAccel;
outputData myData; // Struct for the accelerometer's data
// 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"
#define CHARACTERISTIC_ACCX_UUID "fb6cf981-31cc-4f36-af06-1f2f3e919840"
#define CHARACTERISTIC_ACCY_UUID "35b17f66-73d1-4c92-92f6-9032ef1987d3"
#define CHARACTERISTIC_ACCZ_UUID "3cab9341-e65b-46e9-83ed-c8a7f2f841c2"
// makes the chracteristic globlal
static BLECharacteristic *pCharacteristicAccX;
static BLECharacteristic *pCharacteristicAccY;
static BLECharacteristic *pCharacteristicAccZ;
void setup() {

  Serial.begin(115200);
  Serial.println("Starting BLE work!");
  Wire.begin();
  //connect the accelerometer to the board using qwiic cables
  if (!kxAccel.begin())
  {
    Serial.println("Could not communicate with the the KX13X.");
    while (1)
      ;
  }
   if (kxAccel.softwareReset())
    Serial.println("Reset.");

  // Give some time for the accelerometer to reset.
  // It needs two, but give it five for good measure.
  delay(5);

  // Many settings for KX13X can only be
  // applied when the accelerometer is powered down.
  // However there are many that can be changed "on-the-fly"
  // check datasheet for more info, or the comments in the
  // "...regs.h" file which specify which can be changed when.
  kxAccel.enableAccel(false);

  kxAccel.setRange(SFE_KX132_RANGE16G); // 16g Range
  // kxAccel.setRange(SFE_KX134_RANGE16G);         // 16g for the KX134

  kxAccel.enableDataEngine(); // Enables the bit that indicates data is ready.
  // kxAccel.setOutputDataRate(); // Default is 50Hz
  kxAccel.enableAccel();
  BLEDevice::init("Long name works now");
  BLEServer *pServer = BLEDevice::createServer();
  BLEService *pService = pServer->createService(SERVICE_UUID);
  BLECharacteristic *pCharacteristic = pService->createCharacteristic(
                                         CHARACTERISTIC_UUID,
                                         BLECharacteristic::PROPERTY_READ |
                                         BLECharacteristic::PROPERTY_WRITE
                                       );
  pCharacteristicAccX = pService->createCharacteristic(
                                         CHARACTERISTIC_ACCX_UUID,
                                         BLECharacteristic::PROPERTY_READ |
                                         BLECharacteristic::PROPERTY_WRITE
                                       );
  pCharacteristicAccY = pService->createCharacteristic(
                                         CHARACTERISTIC_ACCY_UUID,
                                         BLECharacteristic::PROPERTY_READ |
                                         BLECharacteristic::PROPERTY_WRITE
                                       );
pCharacteristicAccZ = pService->createCharacteristic(
                                         CHARACTERISTIC_ACCZ_UUID,
                                         BLECharacteristic::PROPERTY_READ |
                                         BLECharacteristic::PROPERTY_WRITE
                                       );
  pCharacteristic->setValue("Hello World says Neil");
  pService->start();
  // BLEAdvertising *pAdvertising = pServer->getAdvertising();  // this still is working for backward compatibility
  BLEAdvertising *pAdvertising = BLEDevice::getAdvertising();
  pAdvertising->addServiceUUID(SERVICE_UUID);
  pAdvertising->setScanResponse(true);
  pAdvertising->setMinPreferred(0x06);  
  pAdvertising->setMinPreferred(0x12);
  BLEDevice::startAdvertising();
  Serial.println("Characteristic defined!");
}

void loop() {
  // put your main code here, to run repeatedly:
  if (kxAccel.dataReady())
  {
    float tempX = myData.xData;//gives the pCharacteristic the pointer insted of the value
    pCharacteristicAccX->setValue(tempX);//setValue takes uint8_t, uint16_t, uint32_t, int, float, double and string
    float tempY =myData.yData;
    pCharacteristicAccY->setValue(tempY);
    float tempZ = myData.zData;
    pCharacteristicAccZ->setValue(tempZ);
    kxAccel.getAccelData(&myData);
    Serial.print(tempX, 4);
    Serial.print("\t");
    Serial.print(tempY, 4);
    Serial.print("\t");
    Serial.println(tempZ, 4);
  }
  delay(100);// 100 ms
}

/**
 * A BLE client example that is rich in capabilities.
 * There is a lot new capabilities implemented.
 * author unknown
 * updated by chegewara
 */

#include "BLEDevice.h"
//#include "BLEScan.h"

// The remote service we wish to connect to.
static BLEUUID serviceUUID("4fafc201-1fb5-459e-8fcc-c5c9c331914b");
// The characteristic of the remote service we are interested in.
static BLEUUID    charUUID("beb5483e-36e1-4688-b7f5-ea07361b26a8");
static BLEUUID    charAccXUUID("fb6cf981-31cc-4f36-af06-1f2f3e919840");// use the same UUID as on the server
static BLEUUID    charAccYUUID("35b17f66-73d1-4c92-92f6-9032ef1987d3");
static BLEUUID    charAccZUUID("3cab9341-e65b-46e9-83ed-c8a7f2f841c2");
//#define CHARACTERISTIC_ACC_UUID 
static boolean doConnect = false;
static boolean connected = false;
static boolean doScan = false;
static BLERemoteCharacteristic* pRemoteCharacteristic;
static BLERemoteCharacteristic* pRemoteCharacteristicACCx;
static BLERemoteCharacteristic* pRemoteCharacteristicACCy;
static BLERemoteCharacteristic* pRemoteCharacteristicACCz;
static BLEAdvertisedDevice* myDevice;

static void notifyCallback(
  BLERemoteCharacteristic* pBLERemoteCharacteristic,
  uint8_t* pData,
  size_t length,
  bool isNotify) {
    Serial.print("Notify callback for characteristic ");
    Serial.print(pBLERemoteCharacteristic->getUUID().toString().c_str());
    Serial.print(" of data length ");
    Serial.println(length);
    Serial.print("data: ");
    Serial.println((char*)pData);
}

class MyClientCallback : public BLEClientCallbacks {
  void onConnect(BLEClient* pclient) {
  }

  void onDisconnect(BLEClient* pclient) {
    connected = false;
    Serial.println("onDisconnect");
  }
};

bool connectToServer() {
    Serial.print("Forming a connection to ");
    Serial.println(myDevice->getAddress().toString().c_str());

    BLEClient*  pClient  = BLEDevice::createClient();
    Serial.println(" - Created client");

    pClient->setClientCallbacks(new MyClientCallback());

    // Connect to the remove BLE Server.
    pClient->connect(myDevice);  // if you pass BLEAdvertisedDevice instead of address, it will be recognized type of peer device address (public or private)
    Serial.println(" - Connected to server");
    pClient->setMTU(517); //set client to request maximum MTU from server (default is 23 otherwise)

    // Obtain a reference to the service we are after in the remote BLE server.
    BLERemoteService* pRemoteService = pClient->getService(serviceUUID);
    if (pRemoteService == nullptr) {
      Serial.print("Failed to find our service UUID: ");
      Serial.println(serviceUUID.toString().c_str());
      pClient->disconnect();
      return false;
    }
    Serial.println(" - Found our service");

    // Obtain a reference to the characteristic in the service of the remote BLE server.
    pRemoteCharacteristic = pRemoteService->getCharacteristic(charUUID);
    if (pRemoteCharacteristic == nullptr) {
      Serial.print("Failed to find our characteristic UUID: ");
      Serial.println(charUUID.toString().c_str());
      pClient->disconnect();
      return false;
    }
    Serial.println(" - Found our characteristic");
    //ACC X Obtain a reference to the characteristic in the service of the remote BLE server.
    pRemoteCharacteristicACCx = pRemoteService->getCharacteristic(charAccXUUID);
    if (pRemoteCharacteristicACCx == nullptr) {
      Serial.print("Failed to find our characteristic UUID x: ");
      Serial.println(charAccXUUID.toString().c_str());
      pClient->disconnect();
      return false;
    }
    Serial.println(" - Found our characteristic");
 //ACC Y Obtain a reference to the characteristic in the service of the remote BLE server.
    pRemoteCharacteristicACCy = pRemoteService->getCharacteristic(charAccYUUID);
    if (pRemoteCharacteristicACCy == nullptr) {
      Serial.print("Failed to find our characteristic UUID y: ");
      Serial.println(charAccYUUID.toString().c_str());
      pClient->disconnect();
      return false;
    }
    Serial.println(" - Found our characteristic");
     //ACC Z Obtain a reference to the characteristic in the service of the remote BLE server.
    pRemoteCharacteristicACCz = pRemoteService->getCharacteristic(charAccZUUID);
    if (pRemoteCharacteristicACCz == nullptr) {
      Serial.print("Failed to find our characteristic UUID z: ");
      Serial.println(charAccZUUID.toString().c_str());
      pClient->disconnect();
      return false;
    }
    Serial.println(" - Found our characteristic");
    // Read the value of the characteristic.
    if(pRemoteCharacteristic->canRead()) {
      std::string value = pRemoteCharacteristic->readValue();
      Serial.print("The characteristic value was: ");
      Serial.println(value.c_str());
    }

    if(pRemoteCharacteristic->canNotify())
      pRemoteCharacteristic->registerForNotify(notifyCallback);

    connected = true;
    return true;
}
/**
 * Scan for BLE servers and find the first one that advertises the service we are looking for.
 */
class MyAdvertisedDeviceCallbacks: public BLEAdvertisedDeviceCallbacks {
 /**
   * Called for each advertising BLE server.
   */
  void onResult(BLEAdvertisedDevice advertisedDevice) {
    Serial.print("BLE Advertised Device found: ");
    Serial.println(advertisedDevice.toString().c_str());

    // We have found a device, let us now see if it contains the service we are looking for.
    if (advertisedDevice.haveServiceUUID() && advertisedDevice.isAdvertisingService(serviceUUID)) {

      BLEDevice::getScan()->stop();
      myDevice = new BLEAdvertisedDevice(advertisedDevice);
      doConnect = true;
      doScan = true;

    } // Found our server
  } // onResult
}; // MyAdvertisedDeviceCallbacks


void setup() {
  Serial.begin(115200);
  Serial.println("Starting Arduino BLE Client application...");
  BLEDevice::init("");

  // Retrieve a Scanner and set the callback we want to use to be informed when we
  // have detected a new device.  Specify that we want active scanning and start the
  // scan to run for 5 seconds.
  BLEScan* pBLEScan = BLEDevice::getScan();
  pBLEScan->setAdvertisedDeviceCallbacks(new MyAdvertisedDeviceCallbacks());
  pBLEScan->setInterval(1349);
  pBLEScan->setWindow(449);
  pBLEScan->setActiveScan(true);
  pBLEScan->start(5, false);
} // End of setup.


// This is the Arduino main loop function.
void loop() {

  // If the flag "doConnect" is true then we have scanned for and found the desired
  // BLE Server with which we wish to connect.  Now we connect to it.  Once we are 
  // connected we set the connected flag to be true.
  if (doConnect == true) {
    if (connectToServer()) {
      Serial.println("We are now connected to the BLE Server.");
    } else {
      Serial.println("We have failed to connect to the server; there is nothin more we will do.");
    }
    doConnect = false;
  }

  // If we are connected to a peer BLE Server, update the characteristic each time we are reached
  // with the current time since boot.
  if (connected) {
    String newValue = "Time since boot: " + String(millis()/1000);
    //Serial.println("Setting new characteristic value to \"" + newValue + "\"");

    // Set the characteristic's value to be the array of bytes that is actually a string.
   // pRemoteCharacteristic->writeValue(newValue.c_str(), newValue.length());//***********JKO
  }else if(doScan){
    BLEDevice::getScan()->start(0);  // this is just example to start scan after disconnect, most likely there is better way to do it in arduino
  }


// read the Characteristics and store them in a variable
// This also makes the print command do float handling
float XValue = pRemoteCharacteristicACCx->readFloat();
float YValue = pRemoteCharacteristicACCy->readFloat();
float ZValue = pRemoteCharacteristicACCz->readFloat();
Serial.print(XValue);
Serial.print("\t");
Serial.print(YValue);
Serial.print("\t");
Serial.println(ZValue);

delay(100); // Delay a 100 ms between loops. 
} // End of loop