This post show how to implement BLE UART communication between NodeMCU
ESP-S3-12K-Kit (in Arduino framework usiing arduino-esp32) and HC-42 BLE
Module.
For HC-42 BLE Module, refer to last post "HC-42 BLE 5 Serial Port Communication Module".
For
ESP-S3-12K-Kit (arduino-esp32 2.0.3)
side, basically it is modified from "ESP32 BLE Arduino" > "BLE_client"
example.
Note that in HC-42:
- Search UUID: FFF0
-
Service UUID: FFE0
- Transparent data transmission UUID: FFE1
We
have to follow it in arduino code in ESP-S3-12K-Kit.
ESP32S3_BLE_client_HC42.ino, modified from "ESP32 BLE Arduino" > "BLE_client" example, for HC-42.
/**
* 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"
#define SEARCH_UUID "FFF0"
#define SERVICE_UUID "FFE0"
#define TRAN_UUID "FFE1"
// The remote service we wish to connect to.
static BLEUUID searchUUID(SEARCH_UUID);
static BLEUUID serviceUUID(SERVICE_UUID);
// The characteristic of the remote service we are interested in.
static BLEUUID charUUID(TRAN_UUID);
static boolean doConnect = false;
static boolean connected = false;
static boolean doScan = false;
static BLERemoteCharacteristic* pRemoteCharacteristic;
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");
// 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(searchUUID)) {
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 + "\"");
// Set the characteristic's value to be the array of bytes
// that is actually a string.
pRemoteCharacteristic->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(1000); // Delay a second between loops.
} // End of loop
ESP32S3_BLE_uart_client_HC42.ino, bi-directional BLE UART communication.
/**
* A BLE UART client example run on ESP32-S3,
* act as client, connect to HC-42, to establish
* BLE UART communication.
*
* Modified from "ESP32 BLE Arduino" > "BLE_client"
*/
#include "BLEDevice.h"
//#include "BLEScan.h"
#define SEARCH_UUID "FFF0"
#define SERVICE_UUID "FFE0"
#define TRANS_UUID "FFE1"
// The remote service we wish to connect to.
static BLEUUID searchUUID(SEARCH_UUID);
static BLEUUID serviceUUID(SERVICE_UUID);
// The characteristic of the remote service we are interested in.
static BLEUUID charUUID(TRANS_UUID);
static boolean doConnect = false;
static boolean connected = false;
static boolean doScan = false;
static BLERemoteCharacteristic* pRemoteCharacteristic;
static BLEAdvertisedDevice* myDevice;
static void notifyCallback(
BLERemoteCharacteristic* pBLERemoteCharacteristic,
uint8_t* pData,
size_t length,
bool isNotify) {
if (length > 0){
Serial.printf("%i :\t", length);
for (int i=0; i<length; i++)
Serial.print((char) pData[i]);
Serial.println();
}
}
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");
// 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(searchUUID)) {
BLEDevice::getScan()->stop();
myDevice = new BLEAdvertisedDevice(advertisedDevice);
doConnect = true;
doScan = true;
} // Found our server
} // onResult
}; // MyAdvertisedDeviceCallbacks
void setup() {
Serial.begin(115200);
delay(1000); //it's seem that adding delay here make it more stable
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) {
if (Serial.available()) {
String newValue = "";
while(Serial.available()){
char c = Serial.read();
newValue += c;
}
newValue += "\n";
Serial.println(newValue);
pRemoteCharacteristic->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(1000); // Delay a second between loops.
} // End of loop
