2.- App send text to ESP32. Show on the Serial Monitor.
p110i_esp32_ble_enviar.aia (220.5 KB)
- Write and Send a text.
- Texts are sent in packages of 20 characters.
- Send: “El Ñandú corrió por Cádiz”
- Receive: “El Ñandú corrió p” = 17 chars + special chars: Ñ,ú,ó need 2 bytes.
/*
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.
}
- The default Minimum Transmission Unit MTU is 20 bytes.
- With block RequestMTU, I have been able to increase it to 22 bytes.