Receive Two Characteristics with BLE
Posted: Sun Mar 21, 2021 7:19 am
Hello, I have am trying to receive two characteristics on an ESP32. I have an Arduino that is sending a random integer between 1 and 100 and the ESP32 is reading it. I am using the BLE_client example and everything works fine when reading one characteristic. I've been trying to edit the example to do the same thing for a second characteristic, but I feel like I'm getting way off. I've attached my code that sends data. I've also attached the modified BLE client example, but its pretty messy because I don't understand this well. With this modified client example, it won't even connect to the arduino. Does anyone happen to have any tips for how to structure code to receive a second characteristics or have example of an ESP32 reading two characteristics? Thank you.
Code: Select all
//this arduino sends two numbers
#include <ArduinoBLE.h>
#include <Arduino_LSM6DS3.h>
BLEService IMUservice("1101");
BLEUnsignedCharCharacteristic pitchChar("2101", BLERead | BLENotify);
BLEUnsignedCharCharacteristic rollChar("3101", BLERead | BLENotify);
void setup() {
Serial.begin(9600);
pinMode(LED_BUILTIN, OUTPUT);
if (!BLE.begin())
{
while (1);
}
BLE.setLocalName("IMU");
BLE.setAdvertisedService(IMUservice);
IMUservice.addCharacteristic(pitchChar);
IMUservice.addCharacteristic(rollChar);
BLE.addService(IMUservice);
BLE.advertise();
}
void loop()
{
BLEDevice central = BLE.central();
if (central)
{
digitalWrite(LED_BUILTIN, HIGH);
while (central.connected()) {
// //pitch+=1;
// //roll-=1;
int Pitch=random(99);
int Roll=random(99);
pitchChar.writeValue(Pitch);
Serial.print(Pitch);
rollChar.writeValue(Roll);
Serial.print(Roll);
delay(100);
}
}
digitalWrite(LED_BUILTIN, LOW);
}
Code: Select all
/**
* A BLE client example that is rich in capabilities.
* There is a lot new capabilities implemented.
* author unknown
* updated by chegewara
*/
#include <M5Core2.h>
#include "BLEDevice.h"
//#include "BLEScan.h"
// The remote service we wish to connect to.
static BLEUUID serviceUUID("1101");
// The characteristic of the remote service we are interested in.
static BLEUUID charUUID("2101");
static BLEUUID charUUID1("3101");
static boolean doConnect = false;
static boolean connected = false;
static boolean doScan = false;
static BLERemoteCharacteristic* pRemoteCharacteristic;
static BLERemoteCharacteristic* pRemoteCharacteristic1;
static BLEAdvertisedDevice* myDevice;
int carmpitch;
char cp[10];
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.printf("%d\n", pData[0]);
//int pitch = pData[0] - '0';
carmpitch = (int)pData[0];
if(carmpitch >= 10){
sprintf(cp,"%02d", carmpitch); // XXX.XX
} else {
sprintf(cp, "%2d \n", carmpitch);
}
M5.Lcd.setCursor(100, 100);
M5.Lcd.print(cp); //cp or carmpitch
//Serial.println(carmpitch);
}
static void notifyCallback1(
BLERemoteCharacteristic* pBLERemoteCharacteristic1,
uint8_t* pData1,
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.printf("%d\n", pData1[0]);
Serial.print("\n");
}
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.
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;
}
// Obtain a reference to the characteristic in the service of the remote BLE server.
pRemoteCharacteristic1 = pRemoteService->getCharacteristic(charUUID1);
if (pRemoteCharacteristic1 == nullptr) {
Serial.print("Failed to find our characteristic UUID: ");
Serial.println(charUUID1.toString().c_str());
pClient->disconnect();
return false;
}
Serial.println(" - Found our characteristics");
// 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());
}
// Read the value of the characteristic.
if(pRemoteCharacteristic1->canRead()) {
std::string value1 = pRemoteCharacteristic1->readValue();
Serial.print("The characteristic value was: ");
Serial.println(value1.c_str());
}
if(pRemoteCharacteristic->canNotify())
pRemoteCharacteristic->registerForNotify(notifyCallback);
if(pRemoteCharacteristic1->canNotify())
pRemoteCharacteristic1->registerForNotify(notifyCallback1);
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() {
M5.begin();
M5.Lcd.fillScreen(BLACK);
M5.Lcd.setTextColor(GREEN , BLACK);
M5.Lcd.setTextSize(2);
delay(2000);
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(connected==false && doScan==true){
BLEDevice::getScan()->start(0); // this is just eample to start scan after disconnect, most likely there is better way to do it in arduino
}
// 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());
// }else if(doScan){
// BLEDevice::getScan()->start(0); // this is just eample 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