It's a BLE UART Client exercise run on ESP2-DevKitC using arduino-esp32 framework. Connect to cpyPico_ESP32_BLE.py in Raspberry Pi Pico/CircuitPython + ESP32/adafruit nina-fw (act as WiFi/BLE Co-Processor).
It search BLE device with specified service UUID, and characteristics for TX and RX. Then sending something every 5 seconds. In the Pico/CircuitPython +ESP32/nina-fw server side, receive and echo back every bytes. This client then print the received byte on Terminal.
ESP32_BLE_client.ino/*
Modify from Arduino Examples for ESP32 Dev Module:
> ESP32 BLE Arduino > BLE_client
*/
#include "BLEDevice.h"
//#include "BLEScan.h"
#define SERVICE_UUID "6E400001-B5A3-F393-E0A9-E50E24DCCA9E" // UART service UUID
#define CHARACTERISTIC_UUID_RX "6E400002-B5A3-F393-E0A9-E50E24DCCA9E" // RX Characteristic
#define CHARACTERISTIC_UUID_TX "6E400003-B5A3-F393-E0A9-E50E24DCCA9E" // TX Characteristic
static BLEUUID serviceUUID(SERVICE_UUID);
static BLEUUID charUUID_RX(CHARACTERISTIC_UUID_RX);
static BLEUUID charUUID_TX(CHARACTERISTIC_UUID_TX);
static boolean doConnect = false;
static boolean connected = false;
static boolean doScan = false;
static BLERemoteCharacteristic* pTXCharacteristic;
static BLERemoteCharacteristic* pRXCharacteristic;
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);
*/
Serial.print((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");
// 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.
// charUUID_TX
pTXCharacteristic = pRemoteService->getCharacteristic(charUUID_TX);
if (pTXCharacteristic == nullptr) {
Serial.print("Failed to find our characteristic UUID: ");
Serial.println(charUUID_TX.toString().c_str());
pClient->disconnect();
return false;
}
Serial.println(" - Found charUUID_TX characteristic");
// Read the value of the characteristic.
if(pTXCharacteristic->canRead()) {
std::string value = pTXCharacteristic->readValue();
Serial.print("The characteristic value was: ");
Serial.println(value.c_str());
}
if(pTXCharacteristic->canNotify())
pTXCharacteristic->registerForNotify(notifyCallback);
// =================================================================================
// Obtain a reference to the characteristic in the service of the remote BLE server.
// charUUID_RX
pRXCharacteristic = pRemoteService->getCharacteristic(charUUID_RX);
if (pRXCharacteristic == nullptr) {
Serial.print("Failed to find our characteristic UUID: ");
Serial.println(charUUID_RX.toString().c_str());
pClient->disconnect();
return false;
}
Serial.println(" - Found charUUID_RX characteristic");
String helloValue = "Hello Remote Server";
pRXCharacteristic->writeValue(helloValue.c_str(), helloValue.length());
// =================================================================================
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 + "\n");
//Serial.println("Setting new characteristic value to \"" + newValue + "\"");
String newValue = " " + String(millis()/1000);
// Set the characteristic's value to be the array of bytes that is actually a string.
pRXCharacteristic->writeValue(newValue.c_str(), newValue.length());
}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
}
delay(5000); // Delay a second between loops.
} // End of loop
