Hello friends,
I'll write in this topic about BLE on ESP32, send and receive text, with clock and without clock. Notify. I'll use the codes of Neil Kolban.
0.- Board D1 R32 ESP32.
This is a cheap card ($ 5) with the dimensions and shape of the Arduino UNO, but with the ESP32.
Search images: D1 R32 ESP32
This card has classic Bluetooth, BLE, WiFi, ADC, DAC, and more feature.
This card can be programmed with the Arduino IDE.
There is another smaller ESP32 model.
Search images: D1 Mini ESP32
1.- Software.
---- Connection. Bare minimum.
p110i_esp32_ble_conexion.aia (199.5 KB)
// http://kio4.com/arduino/160_Wemos_ESP32_BLE.htm
#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>
#define SERVICE_UUID "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"
void setup() {
BLEDevice::init("Here_ESP32");
BLEServer *pServer = BLEDevice::createServer();
BLEService *pService = pServer->createService(SERVICE_UUID);
BLECharacteristic *pCharacteristic = pService->createCharacteristic(
CHARACTERISTIC_UUID,
BLECharacteristic::PROPERTY_READ |
BLECharacteristic::PROPERTY_WRITE
);
pCharacteristic->setValue("Connected.");
pService->start();
BLEAdvertising *pAdvertising = pServer->getAdvertising();
pAdvertising->start();
}
void loop() {
// put your main code here, to run repeatedly:
}
2.- App send text to ESP32. Show on the Serial Monitor.
p110i_esp32_ble_enviar.aia (220.5 KB)
/*
Based on Neil Kolban example for IDF:
https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleWrite.cpp
Ported to Arduino ESP32 by Evandro Copercini
*/
// Modificado por Juan Antonio Villalpando.
// http://kio4.com/arduino/160i_Wemos_ESP32_BLE.htm
#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>
String valor;
#define SERVICE_UUID "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"
class MyCallbacks: public BLECharacteristicCallbacks {
void onWrite(BLECharacteristic *pCharacteristic) {
std::string value = pCharacteristic->getValue();
if (value.length() > 0) {
valor = "";
for (int i = 0; i < value.length(); i++){
// Serial.print(value[i]); // Presenta value.
valor = valor + value[i];
}
Serial.println("*********");
Serial.print("valor = ");
Serial.println(valor); // Presenta valor.
}
}
};
void setup() {
Serial.begin(115200);
BLEDevice::init("MyESP32");
BLEServer *pServer = BLEDevice::createServer();
BLEService *pService = pServer->createService(SERVICE_UUID);
BLECharacteristic *pCharacteristic = pService->createCharacteristic(
CHARACTERISTIC_UUID,
BLECharacteristic::PROPERTY_READ |
BLECharacteristic::PROPERTY_WRITE
);
pCharacteristic->setCallbacks(new MyCallbacks());
pCharacteristic->setValue("Hello World");
pService->start();
BLEAdvertising *pAdvertising = pServer->getAdvertising();
pAdvertising->start();
}
void loop() {
// put your main code here, to run repeatedly:
delay(2000);
// Serial.println("valor en el loop = ");
// Serial.println(valor); // Presenta valor.
}
3.- App sends text and receives random number. With Clock.
p110i_esp32_ble_recibir.aia (221.0 KB)
/*
Based on Neil Kolban example for IDF:
https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleWrite.cpp
Ported to Arduino ESP32 by Evandro Copercini
*/
// Modificado por Juan Antonio Villalpando.
// http://kio4.com/arduino/160i_Wemos_ESP32_BLE.htm
#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>
String valor;
int aleatorio;
String alea = "2";
#define SERVICE_UUID "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"
class MyCallbacks: public BLECharacteristicCallbacks {
void onWrite(BLECharacteristic *pCharacteristic) {
std::string value = pCharacteristic->getValue();
pCharacteristic->setValue(alea.c_str()); // Pone el numero aleatorio
if (value.length() > 0) {
valor = "";
for (int i = 0; i < value.length(); i++){
// Serial.print(value[i]); // Presenta value.
valor = valor + value[i];
}
Serial.println("*********");
Serial.print("valor = ");
Serial.println(valor); // Presenta valor.
}
}
};
void setup() {
Serial.begin(115200);
BLEDevice::init("MyESP32");
BLEServer *pServer = BLEDevice::createServer();
BLEService *pService = pServer->createService(SERVICE_UUID);
BLECharacteristic *pCharacteristic = pService->createCharacteristic(
CHARACTERISTIC_UUID,
BLECharacteristic::PROPERTY_READ |
BLECharacteristic::PROPERTY_WRITE
);
pCharacteristic->setCallbacks(new MyCallbacks());
pCharacteristic->setValue("Iniciado.");
pService->start();
BLEAdvertising *pAdvertising = pServer->getAdvertising();
pAdvertising->start();
}
void loop() {
// put your main code here, to run repeatedly:
delay(2000);
//Serial.println("valor en el loop = ");
//Serial.println(valor); // Presenta valor.
aleatorio = random(1,100); // Crea el numero aleatorio.
alea = (String) aleatorio; // Lo convierte en String.
}
4.- App sends text and receives random number. Without Clock.
p110i_esp32_ble_enviar_recibir.aia (220.9 KB)
// Modificado por Juan Antonio Villalpando.
// http://kio4.com/arduino/160i_Wemos_ESP32_BLE.htm
#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>
String valor;
int aleatorio;
String alea;
#define SERVICE_UUID "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"
class MyCallbacks: public BLECharacteristicCallbacks {
void onWrite(BLECharacteristic *pCharacteristic) {
std::string value = pCharacteristic->getValue();
pCharacteristic->setValue(alea.c_str()); // Pone el numero aleatorio
if (value.length() > 0) {
valor = "";
for (int i = 0; i < value.length(); i++){
// Serial.print(value[i]); // Presenta value.
valor = valor + value[i];
}
Serial.println("*********");
Serial.print("valor = ");
Serial.println(valor); // Presenta valor.
}
}
};
void setup() {
Serial.begin(115200);
BLEDevice::init("MyESP32");
BLEServer *pServer = BLEDevice::createServer();
BLEService *pService = pServer->createService(SERVICE_UUID);
BLECharacteristic *pCharacteristic = pService->createCharacteristic(
CHARACTERISTIC_UUID,
BLECharacteristic::PROPERTY_READ |
BLECharacteristic::PROPERTY_WRITE
);
pCharacteristic->setCallbacks(new MyCallbacks());
pCharacteristic->setValue("Iniciado.");
pService->start();
BLEAdvertising *pAdvertising = pServer->getAdvertising();
pAdvertising->start();
}
void loop() {
delay(1000);
aleatorio = random(1,100); // Crea el numero aleatorio.
alea = (String) aleatorio; // Lo convierte en String.aleatorio
}
5.- App sends text and receives according to the text sent a random number. Without Clock.
The same application as the previous example: p110i_esp32_ble_enviar_recibir.aia (220.9 KB)
If send text: uno, receive a random number: 1…50
If send text: dos, receive a random number: 100…200
Ir send text: tres, receive two random numbers: (1…50,100…200)
// Modificado por Juan Antonio Villalpando.
// http://kio4.com/arduino/160i_Wemos_ESP32_BLE.htm
#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>
String valor;
int aleatorio1;
int aleatorio2;
String alea1;
String alea2;
String alea3;
#define SERVICE_UUID "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"
class MyCallbacks: public BLECharacteristicCallbacks {
void onWrite(BLECharacteristic *pCharacteristic) {
std::string value = pCharacteristic->getValue();
if (value.length() > 0) {
valor = "";
for (int i = 0; i < value.length(); i++){
// Serial.print(value[i]); // Presenta value.
valor = valor + value[i];
}
Serial.println("*********");
Serial.print("valor = ");
Serial.println(valor); // Presenta valor.
if(valor == "uno") {
pCharacteristic->setValue(alea1.c_str()); // Pone el numero aleatorio
}
if(valor == "dos") {
pCharacteristic->setValue(alea2.c_str()); // Pone el numero aleatorio
}
if(valor == "tres") {
pCharacteristic->setValue(alea3.c_str()); // Pone el numero aleatorio
}
}
}
};
void setup() {
Serial.begin(115200);
BLEDevice::init("MyESP32");
BLEServer *pServer = BLEDevice::createServer();
BLEService *pService = pServer->createService(SERVICE_UUID);
BLECharacteristic *pCharacteristic = pService->createCharacteristic(
CHARACTERISTIC_UUID,
BLECharacteristic::PROPERTY_READ |
BLECharacteristic::PROPERTY_WRITE
);
pCharacteristic->setCallbacks(new MyCallbacks());
pCharacteristic->setValue("Iniciado.");
pService->start();
BLEAdvertising *pAdvertising = pServer->getAdvertising();
pAdvertising->start();
}
void loop() {
delay(1000);
aleatorio1 = random(1,50); // Crea el numero aleatorio.
alea1 = (String) aleatorio1; // Lo convierte en String.aleatorio
aleatorio2 = random(100,200); // Crea el numero aleatorio.
alea2 = (String) aleatorio2; // Lo convierte en String.aleatorio
alea3 = alea1 + "," + alea2;
}
6.- ESP32 sends automatically (Notify) a random number to App.
p110i_esp32_ble_notifica.aia (220.6 KB)
The Bluetooth LE specification includes a mechanism known as notify that lets you know when data’s changed. When notify on a characteristic is enabled and the sender writes to it, the new value is automatically sent to the receiver, without the receiver explicitly issuing a read command. (Reference ArduinoBLE)
ESP32 code generates a random number every 500 milisecond and notifies (sends) it to the application.
/*
Based on Neil Kolban example for IDF:
https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleNotify.cpp
Ported to Arduino ESP32 by Evandro Copercini updated by chegewara
Create a BLE server that, once we receive a connection, will send periodic notifications.
A connect hander associated with the server starts a background task that performs notification
every couple of seconds.
*/
// Modificado por Juan A. Villalpando
// http://kio4.com/arduino/160i_Wemos_ESP32_BLE.htm
#include <BLEDevice.h>
#include <BLEServer.h>
#include <BLEUtils.h>
#include <BLE2902.h>
BLEServer* pServer = NULL;
BLECharacteristic* pCharacteristic = NULL;
bool deviceConnected = false;
bool oldDeviceConnected = false;
uint32_t value = 0;
// 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"
class MyServerCallbacks: public BLEServerCallbacks {
void onConnect(BLEServer* pServer) {
deviceConnected = true;
};
void onDisconnect(BLEServer* pServer) {
deviceConnected = false;
}
};
void setup() {
Serial.begin(115200);
// Create the BLE Device
BLEDevice::init("MyESP32");
// Create the BLE Server
pServer = BLEDevice::createServer();
pServer->setCallbacks(new MyServerCallbacks());
// Create the BLE Service
BLEService *pService = pServer->createService(SERVICE_UUID);
// Create a BLE Characteristic
pCharacteristic = pService->createCharacteristic(
CHARACTERISTIC_UUID,
BLECharacteristic::PROPERTY_READ |
BLECharacteristic::PROPERTY_WRITE |
BLECharacteristic::PROPERTY_NOTIFY |
BLECharacteristic::PROPERTY_INDICATE
);
// https://www.bluetooth.com/specifications/gatt/viewer?
// attributeXmlFile=org.bluetooth.descriptor.gatt.client_characteristic_configuration.xml
// Create a BLE Descriptor
pCharacteristic->addDescriptor(new BLE2902());
// Start the service
pService->start();
// Start advertising
BLEAdvertising *pAdvertising = BLEDevice::getAdvertising();
pAdvertising->addServiceUUID(SERVICE_UUID);
pAdvertising->setScanResponse(false);
pAdvertising->setMinPreferred(0x0); // set value to 0x00 to not advertise this parameter
BLEDevice::startAdvertising();
Serial.println("Waiting a client connection to notify...");
}
void loop() {
// notify changed value
if (deviceConnected) {
// pCharacteristic->setValue((uint8_t*)&value, 4);
int aleatorio = random(1,100); // Crea el numero aleatorio.
String alea = (String) aleatorio; // Lo convierte en String.
pCharacteristic->setValue(alea.c_str()); // Pone el numero aleatorio
pCharacteristic->notify();
delay(500); // bluetooth stack will go into congestion, if too many packets are sent.
}
// disconnecting
if (!deviceConnected && oldDeviceConnected) {
delay(500); // give the bluetooth stack the chance to get things ready
pServer->startAdvertising(); // restart advertising
Serial.println("start advertising");
oldDeviceConnected = deviceConnected;
}
// connecting
if (deviceConnected && !oldDeviceConnected) {
// do stuff here on connecting
oldDeviceConnected = deviceConnected;
}
}
That must have been a lot of work.
I don’t see any use of the Register block in your examples.
I remember a thread
where having it made a difference.
7.- App sends a number by a Slider to ESP32. ESP32 return double. Notify.
p110i_esp32_ble_notifica_Deslizador.aia (221.1 KB)
/*
Video: https://www.youtube.com/watch?v=oCMOYS71NIU
Based on Neil Kolban example for IDF:
https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleNotify.cpp
Ported to Arduino ESP32 by Evandro Copercini
updated by chegewara
Create a BLE server that, once we receive a connection, will send periodic notifications.
A connect hander associated with the server starts a background task that performs notification
every couple of seconds.
*/
// Modificado por Juan A. Villalpando
// http://kio4.com/arduino/160i_Wemos_ESP32_BLE.htm
#include <BLEDevice.h>
#include <BLEServer.h>
#include <BLEUtils.h>
#include <BLE2902.h>
String valor;
BLEServer* pServer = NULL;
BLECharacteristic* pCharacteristic = NULL;
bool deviceConnected = false;
bool oldDeviceConnected = false;
//uint32_t value = 0;
#define SERVICE_UUID "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"
class MyServerCallbacks: public BLEServerCallbacks {
void onConnect(BLEServer* pServer) {
deviceConnected = true;
};
void onDisconnect(BLEServer* pServer) {
deviceConnected = false;
}
};
////////////////////// WriteStrings /////////////////////////////
class MyCallbacks: public BLECharacteristicCallbacks {
void onWrite(BLECharacteristic *pCharacteristic) {
std::string value = pCharacteristic->getValue();
if (value.length() > 0) {
valor = "";
for (int i = 0; i < value.length(); i++){
// Serial.print(value[i]); // Presenta value.
valor = valor + value[i];
}
Serial.println("*********");
Serial.print("valor = ");
Serial.println(valor); // Presenta valor.
}
}
};
///////////////////////////////////////////////////
void setup() {
Serial.begin(115200);
// Create the BLE Device
BLEDevice::init("MyESP32");
// Create the BLE Server
pServer = BLEDevice::createServer();
pServer->setCallbacks(new MyServerCallbacks());
// Create the BLE Service
BLEService *pService = pServer->createService(SERVICE_UUID);
// Create a BLE Characteristic
pCharacteristic = pService->createCharacteristic(
CHARACTERISTIC_UUID,
BLECharacteristic::PROPERTY_READ |
BLECharacteristic::PROPERTY_WRITE |
BLECharacteristic::PROPERTY_NOTIFY |
BLECharacteristic::PROPERTY_INDICATE
);
// https://www.bluetooth.com/specifications/gatt/viewer?
// attributeXmlFile=org.bluetooth.descriptor.gatt.client_characteristic_configuration.xml
// Create a BLE Descriptor
pCharacteristic->addDescriptor(new BLE2902());
// Esta línea es para el WriteStrings:
pCharacteristic->setCallbacks(new MyCallbacks());
// Start the service
pService->start();
// Start advertising
BLEAdvertising *pAdvertising = BLEDevice::getAdvertising();
pAdvertising->addServiceUUID(SERVICE_UUID);
pAdvertising->setScanResponse(false);
pAdvertising->setMinPreferred(0x0); // set value to 0x00 to not advertise this parameter
BLEDevice::startAdvertising();
Serial.println("Waiting a client connection to notify...");
}
void loop() {
// notify changed value
if (deviceConnected) {
std::string value = pCharacteristic->getValue();
// pCharacteristic->setValue((uint8_t*)&value, 4);
int doble = valor.toInt() * 2 ;
String doblado = (String) doble; // Lo convierte en String.
pCharacteristic->setValue(doblado.c_str()); // Pone el numero doble
pCharacteristic->notify();
delay(5); // bluetooth stack will go into congestion, if too many packets are sent.
}
// disconnecting
if (!deviceConnected && oldDeviceConnected) {
delay(500); // give the bluetooth stack the chance to get things ready
pServer->startAdvertising(); // restart advertising
Serial.println("start advertising");
oldDeviceConnected = deviceConnected;
}
// connecting
if (deviceConnected && !oldDeviceConnected) {
// do stuff here on connecting
oldDeviceConnected = deviceConnected;
}
}
Regards.
Juan Antonio Villalpando.
More information: http://kio4.com/arduino/160i_Wemos_ESP32_BLE.htm
(This post was edited).
RegisterForStrings also in the examples.
7B.- App sends a number by a Slider to ESP32. ESP32 sends a number from Serial Monitor to app. Notify.
p110i_esp32_ble_notifica_Texto.aia (202.1 KB)
// Juan A. Villalpando
// http://kio4.com/arduino/160_Wemos_ESP32_BLE.htm
#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>
String valor;
BLEServer* pServer = NULL;
BLECharacteristic* pCharacteristic = NULL;
char char_received = '0';
String fromSerial = "";
#define SERVICE_UUID "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"
class MyCallbacks: public BLECharacteristicCallbacks {
// RECEIVE NUMBER FROM APP (Slider).
void onWrite(BLECharacteristic *pCharacteristic) {
std::string value = pCharacteristic->getValue();
if (value.length() > 0) {
valor = "";
for (int i = 0; i < value.length(); i++){
valor = valor + value[i];
}
Serial.println(valor); // Presenta valor.
}
}
};
void setup() {
Serial.begin(115200);
BLEDevice::init("MyESP32");
pServer = BLEDevice::createServer();
BLEService *pService = pServer->createService(SERVICE_UUID);
pCharacteristic = pService->createCharacteristic(
CHARACTERISTIC_UUID,
BLECharacteristic::PROPERTY_READ |
BLECharacteristic::PROPERTY_WRITE |
BLECharacteristic::PROPERTY_NOTIFY |
BLECharacteristic::PROPERTY_INDICATE
);
pCharacteristic->setCallbacks(new MyCallbacks());
pService->start();
BLEAdvertising *pAdvertising = pServer->getAdvertising();
pAdvertising->start();
}
void loop() {
// SEND NUMBER FROM SERIAL MONITOR TO APP.
// Get number from Serial Monitor.
if (Serial.available() > 0) { // ¿Hay algún caracter?
char_received = Serial.read(); // Toma el caracter
fromSerial += char_received;
if (char_received == '\n') {
std::string value = pCharacteristic->getValue();
pCharacteristic->setValue(fromSerial.c_str()); // Notify fromSerial.
pCharacteristic->notify();
delay(5);
fromSerial = "";
}
}
}
I see them now, examples 6 & 7.
Sorry for the confusion!
Invaluable help Juan. A much needed guide.
Juan,
This is great work! I am looking for a way to modify this so that instead of printing the result to the serial monitor it prints it to a 16x2 I2C LCD screen. I am able to get this working in part by adding lcd.print(valor); to the main loop, but of course then it just loops that text on the screen. What I would like to be able to do is to send a bit of text, have it stay on the screen until another string of text is sent. Could you point me in the right direction?
Thank you!
michael
Here a code with ESP32 working as classic Bluetooth and Screen LCD.
Sorry for the bother…
Is this a simple example for receive a command from Esp32 (or Arduino)?
I tried one.
I mean: We can turn on/off a led on Esp32 (Arduino) from cell phone.
But I am not able to turn on/off a “led” on cell phone from Esp32 (Arduino)…
I tried… But it works only if you repress on/off from cell phone…
So I am trying to make a simple app with a simple “ON” or “OFF” and in Esp32 (Arduino) building simple button… (simply writing on terminal)…
How do it???
“When BluetoothLE1.StringsReceived” doesn’t work…
Thanks
@}-,-’-------
Gianfranco
8.- PushButton in ESP2 sends HIGH/LOW to App Inventor. Notify.
p110_esp32_ble_notifica_Pulsador.aia (185.0 KB)
PushButton in pin12 of ESP32 sends “HIGH” or “LOW” to App Inventor by BLE Notify.
It also turns ON/OFF LED2 of the ESP32 (it is a LED_BUILTIN)
/* Based on Neil Kolban example for IDF:
https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleNotify.cpp
Ported to Arduino ESP32 by Evandro Copercini updated by chegewara
Create a BLE server that, once we receive a connection, will send periodic notifications.
A connect hander associated with the server starts a background task that performs notification
every couple of seconds. */
// Modificado por Juan A. Villalpando
// http://kio4.com/arduino/160i_Wemos_ESP32_BLE.htm
#include <BLEDevice.h>
#include <BLEServer.h>
#include <BLEUtils.h>
#include <BLE2902.h>
#define pin12 12 // pin12 PushButton
#define pin2 2 // pin2 LED2
int valor12; // Status PushButton
String output ="LOW"; // Output to App. Notify.
BLEServer* pServer = NULL;
BLECharacteristic* pCharacteristic = NULL;
bool deviceConnected = false;
bool oldDeviceConnected = false;
uint32_t value = 0;
#define SERVICE_UUID "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"
class MyServerCallbacks: public BLEServerCallbacks {
void onConnect(BLEServer* pServer) {
deviceConnected = true;
};
void onDisconnect(BLEServer* pServer) {
deviceConnected = false;
}
};
void setup() {
pinMode(pin12, INPUT); // pin12 PushButton
pinMode(pin2, OUTPUT); // pin2 LED2
Serial.begin(115200);
// Create the BLE Device
BLEDevice::init("MyESP32");
// Create the BLE Server
pServer = BLEDevice::createServer();
pServer->setCallbacks(new MyServerCallbacks());
// Create the BLE Service
BLEService *pService = pServer->createService(SERVICE_UUID);
// Create a BLE Characteristic
pCharacteristic = pService->createCharacteristic(
CHARACTERISTIC_UUID,
BLECharacteristic::PROPERTY_READ |
BLECharacteristic::PROPERTY_WRITE |
BLECharacteristic::PROPERTY_NOTIFY |
BLECharacteristic::PROPERTY_INDICATE
);
// Create a BLE Descriptor
pCharacteristic->addDescriptor(new BLE2902());
// Start the service
pService->start();
// Start advertising
BLEAdvertising *pAdvertising = BLEDevice::getAdvertising();
pAdvertising->addServiceUUID(SERVICE_UUID);
pAdvertising->setScanResponse(false);
pAdvertising->setMinPreferred(0x0); // set value to 0x00 to not advertise this parameter
BLEDevice::startAdvertising();
Serial.println("Waiting a client connection to notify...");
}
void loop() {
// notify changed value
if (deviceConnected) {
pCharacteristic->setValue(output.c_str()); // Output
pCharacteristic->notify();
valor12 = digitalRead(pin12); // Read pin12 --> valor12. ( 0 or 1)
if (valor12 == HIGH) {
digitalWrite(pin2, HIGH); // if valor12 is HIGH, set pin2 HIGH
Serial.println("Pulsado");
output ="HIGH"; // Notify HIGH
}
if (valor12 == LOW) {
digitalWrite(pin2, LOW); // If valor12 is LOW, set pin2 LOW
Serial.println("No Pulsado");
output ="LOW"; // Notify LOW
}
delay(100); // bluetooth stack will go into congestion, if too many packets are sent.
}
// disconnecting
if (!deviceConnected && oldDeviceConnected) {
delay(500); // give the bluetooth stack the chance to get things ready
pServer->startAdvertising(); // restart advertising
Serial.println("start advertising");
oldDeviceConnected = deviceConnected;
}
// connecting
if (deviceConnected && !oldDeviceConnected) {
// do stuff here on connecting
oldDeviceConnected = deviceConnected;
}
}9.- App sends three values for a tricolor LED RGB. Receive those same values.
p110i_esp32_ble_LED.aia (236.1 KB)
// Juan Antonio Villalpando.
// http://kio4.com/arduino/160_Wemos_ESP32_BLE.htm
#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>
#include <Arduino.h>
#include <analogWrite.h>
String valor;
String red;
String green;
String blue;
int ind1;
int ind2;
int ind3;
#define SERVICE_UUID "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"
class MyCallbacks: public BLECharacteristicCallbacks {
void onWrite(BLECharacteristic *pCharacteristic) {
std::string value = pCharacteristic->getValue();
if (value.length() > 0) {
valor = "";
for (int i = 0; i < value.length(); i++){
valor = valor + value[i];
}
Serial.print("valor = ");
Serial.println(valor);
ind1 = valor.indexOf(',');
red = valor.substring(0, ind1);
ind2 = valor.indexOf(',', ind1+1 );
green = valor.substring(ind1+1, ind2);
ind3 = valor.indexOf(',', ind2+1 );
blue = valor.substring(ind2+1);
Serial.print("red = ");
Serial.println(red);
Serial.print("green = ");
Serial.println(green);
Serial.print("blue = ");
Serial.println(blue);
Serial.println();
analogWrite(12, red.toInt());
analogWrite(14, green.toInt());
analogWrite(27, blue.toInt());
pCharacteristic->setValue(valor.c_str()); // Devuelve el valor.
}
}
};
void setup() {
analogWriteResolution(12, 8); // Resolución 8 bits
analogWriteResolution(14, 8);
analogWriteResolution(27, 8);
Serial.begin(115200);
BLEDevice::init("MyESP32");
BLEServer *pServer = BLEDevice::createServer();
BLEService *pService = pServer->createService(SERVICE_UUID);
BLECharacteristic *pCharacteristic = pService->createCharacteristic(
CHARACTERISTIC_UUID,
BLECharacteristic::PROPERTY_READ |
BLECharacteristic::PROPERTY_WRITE
);
pCharacteristic->setCallbacks(new MyCallbacks());
pCharacteristic->setValue("Iniciado.");
pService->start();
BLEAdvertising *pAdvertising = pServer->getAdvertising();
pAdvertising->start();
}
void loop() {
//
}
ESP32 does not have the AnalogWrite function, therefore we must download and install the analogWrite library from:
https://github.com/ERROPiX/ESP32_AnalogWrite
Modifications:
Comment this line:
// pCharacteristic->setValue(valor.c_str()); // Return value.
Change this block:
http://kio4.com/arduino/160_Wemos_ESP32_BLE.htm#7 (in Spanish).
10.- From App ON/OFF 3 LEDs. Get status of the LEDs.
p110i_esp32_ble_3LED.aia (185.7 KB)
// Juan Antonio Villalpando.
// http://kio4.com/arduino/160_Wemos_ESP32_BLE.htm
#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>
String valor;
#define LED12 12 // LED pin 12
#define LED14 14 // LED pin 14
#define LED27 27 // LED pin 27
String estado ="";
#define SERVICE_UUID "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"
class MyCallbacks: public BLECharacteristicCallbacks {
void onWrite(BLECharacteristic *pCharacteristic) {
std::string value = pCharacteristic->getValue();
if (value.length() > 0) {
valor = "";
for (int i = 0; i < value.length(); i++){
valor = valor + value[i];
}
Serial.println(valor);
if (valor == "on12") {digitalWrite(LED12,HIGH); pCharacteristic->setValue("LED12 ON");}
if (valor == "off12"){digitalWrite(LED12,LOW); pCharacteristic->setValue("LED12 OFF");}
if (valor == "on14") {digitalWrite(LED14,HIGH); pCharacteristic->setValue("LED14 ON");}
if (valor == "off14"){digitalWrite(LED14,LOW); pCharacteristic->setValue("LED14 OFF");}
if (valor == "on27") {digitalWrite(LED27,HIGH); pCharacteristic->setValue("LED27 ON");}
if (valor == "off27"){digitalWrite(LED27,LOW); pCharacteristic->setValue("LED27 OFF");}
if (valor == "check"){
estado ="";
if (digitalRead(LED12) == HIGH) {estado = "LED12 ON,";} else {estado = "LED12 OFF,";}
if (digitalRead(LED14) == HIGH) {estado = estado + "LED14 ON,";} else {estado = estado + "LED14 OFF,";}
if (digitalRead(LED27) == HIGH) {estado = estado + "LED27 ON";} else {estado = estado + "LED27 OFF";}
pCharacteristic->setValue(estado.c_str()); // Return status
}
}
}
};
void setup() {
pinMode(LED12, OUTPUT);
pinMode(LED14, OUTPUT);
pinMode(LED27, OUTPUT);
Serial.begin(115200);
BLEDevice::init("MyESP32");
BLEServer *pServer = BLEDevice::createServer();
BLEService *pService = pServer->createService(SERVICE_UUID);
BLECharacteristic *pCharacteristic = pService->createCharacteristic(
CHARACTERISTIC_UUID,
BLECharacteristic::PROPERTY_READ |
BLECharacteristic::PROPERTY_WRITE
);
pCharacteristic->setCallbacks(new MyCallbacks());
pCharacteristic->setValue("Iniciado.");
pService->start();
BLEAdvertising *pAdvertising = pServer->getAdvertising();
pAdvertising->start();
}
void loop() {
//
}11.- App sends Bytes by WriteBytesWithResponse.
p110i_esp32_ble_Bytes.aia (184.3 KB)
// Juan Antonio Villalpando.
// http://kio4.com/arduino/160_Wemos_ESP32_BLE.htm
#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>
String valor;
#define SERVICE_UUID "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"
class MyCallbacks: public BLECharacteristicCallbacks {
void onWrite(BLECharacteristic *pCharacteristic) {
std::string value = pCharacteristic->getValue();
if (value.length() > 0) {
valor = "";
for (int i = 0; i < value.length(); i++){
valor = valor + value[i];
}
Serial.println(valor);
// Convert valor to bytes.
for(int i=0; i<valor.length(); i++){
char myChar = valor.charAt(i);
for(int i=7; i>=0; i--){
byte bytes = bitRead(myChar,i);
Serial.print(bytes, BIN);
}
Serial.println("");
}
pCharacteristic->setValue(valor.c_str()); // Return valor
}
}
};
void setup() {
Serial.begin(115200);
BLEDevice::init("MyESP32");
BLEServer *pServer = BLEDevice::createServer();
BLEService *pService = pServer->createService(SERVICE_UUID);
BLECharacteristic *pCharacteristic = pService->createCharacteristic(
CHARACTERISTIC_UUID,
BLECharacteristic::PROPERTY_READ |
BLECharacteristic::PROPERTY_WRITE
);
pCharacteristic->setCallbacks(new MyCallbacks());
pCharacteristic->setValue("Iniciado.");
pService->start();
BLEAdvertising *pAdvertising = pServer->getAdvertising();
pAdvertising->start();
}
void loop() {
//
}
Check Serial Monitor:
This tutorial in Spanish.
@Juan_Antonio, I’m getting started with esp32 BLE connection and MIT app inventor. I don’t know what is happening, but I got this error when I try to use any off the apps. Can someone help me?
Note: I’m just copying and pasting both code and app
