HM-10. BLE. Arduino UNO. Notify. Bluetooth. AT. iBeacon. Arrhythmia

Juan_Antonio · July 13, 2020, 6:00pm

2.- Final character of a message is NULL.

p110i_UNO_HM10_ble_enviar.aia (183.8 KB)

We are going to send a message (abcdefghijk) and get the bytes obtained in Arduino UNO.

// http://kio4.com/arduino/161_HM10_BLE.htm

#include <SoftwareSerial.h>
// El TXD del módulo al pin 2 (RX) del Arduino.
// El RXD del módulo al pin 3 (TX) del Arduino.
SoftwareSerial HM10(2, 3);

#define LED13  13
byte caracter = "";  
// char caracter = "";  
String mensaje = "";

void setup(){
  Serial.begin(9600);
  HM10.begin(9600);
  pinMode(LED13, OUTPUT);
}

void loop(){
  if(HM10.available()) { 
  caracter = HM10.read();
  Serial.println(caracter);
  mensaje = mensaje + caracter;

  if(caracter == NULL ) { 
     Serial.println(mensaje); 
     if (mensaje.indexOf("on13")>= 0){digitalWrite(LED13, HIGH);}
     if (mensaje.indexOf("off13")>= 0){digitalWrite(LED13, LOW);}   
     mensaje = "";
     delay(100);
     }
  } 
}

Look
byte caracter = "";

hm10_5759×514 22.8 KB
The extension sends the message and at the end the NULL character.
To obtain the characters we change these lines.
// byte caracter = "";
char caracter = "";

BluetoothLE extension adds a NULL character by default

We can remove this feature using the block NullTerminateStrings = false