How to send and receive information between two esp32 devices via bluetooth

Can two esp32 devices send and receive information from each other via bluetooth(ble)? I've been searching the internet but am not getting clear answers. I've read about ESP32 now communication protocol (but don't know exactly if it's low power)

Reason I want to use BLE is for low power usage. Also for unique identification between sender and receiver (i.e. mac addresses, device names) I found these examples online where two arduino devices can send and receive information from each other: Via Bluetooth: http://www.martyncurrey.com/hm-10-bluetooth-4ble-modules/#HM-10%20-%20Turning-an-LED-on-and-off Via RF transmission: https://www.instructables.com/id/Long-Range-18km-Arduino-to-Arduino-Wireless-Commun/

However, I want to use low power and add unique names for my receiver and transmitter (i.e. via bluetooth or wifi). Since in the real world if there were tons of these devices I would not want them interfering with each other.

I implemented the RF method for my project and it worked.

RF method receiver code (via HC-12 module):

// Special thanks to geo bruce at instructables.com.
// Special thanks to Robin2 and his code for parsing data, and others on Arduino forums.
// Special thanks to all my software programming friends.
// HC-12 receiver code for dual axis solar tracking.
// Low photoresistor values means less light is placed on them.

#include <SoftwareSerial.h>
SoftwareSerial HC12(11,10); // (HC-12 TX pin, HC-12 RX)

// Azimuth and elevation PWM (pulse width modulation) pins on each h-bridge must be connected to four pwm pins on arduino.
// For uno/micro/pro mini they are: 3,5,6,9,10,11.

int AREN = 7; 
int ARPWM = 6; 
int ALEN = 8;
int ALPWM = 9; // motor azimuth adjustment

int EREN = 2;
int ERPWM = 3; 
int ELEN = 4; 
int ELPWM = 5; // motor elevation adjustment

const byte numChars = 32;
char receivedChars[numChars];
char tempChars[numChars];        // temporary array for use when parsing

// variables to hold the parsed data
int TL = 0; //top right sensor
int BL = 0; //bottom right
int TR = 0; //top left
int BR = 0; //bottom left
int EA = 0; //elevation angle

// Adjustable variables on receiver end
int DT = 2000; //delay time between readings for motors
int TE = 6; //set tolerance value for difference between sensors

boolean newData = false;

//=======================================================================

void setup() {
  Serial.begin(9600); 
  HC12.begin(9600); //serial port to HC12

  pinMode(AREN, OUTPUT); pinMode(ARPWM, OUTPUT); pinMode(ALEN, OUTPUT); pinMode(ALPWM, OUTPUT);  //set all motor control pins to outputs
  pinMode(EREN, OUTPUT); pinMode(ERPWM, OUTPUT); pinMode(ELEN, OUTPUT); pinMode(ELPWM, OUTPUT);
}

void loop() {
  recvWithStartEndMarkers();
  if (newData == true) {
    strcpy(tempChars, receivedChars);
    // this temporary copy is necessary to protect the original data
    // because strtok() used in parseData() replaces the commas with \0

    parseData();
    showParsedData();
    newData = false;
  }

  int avt = (TR + TL) / 2; // average value top
  int avd = (BL + BR) / 2; 
  int avl = (TL + BL) / 2; 
  int avr = (TR + BR) / 2; 

  int dv = avt - avd; // average difference of top and bottom light sensors
  int dh = avl - avr; // average difference of left and right light sensors

  if (-1 * TE > dh || dh > TE) // check if the difference in left and right light sensors is within tolerance range
  {
    if (avl > avr) // if average light sensor values on left side are greater than right side, azimuth motor rotates clockwise
    {
      digitalWrite(AREN, HIGH); analogWrite(ARPWM, 255); // set speed out of possible range 0~255
      digitalWrite(ALEN, HIGH); digitalWrite (ALPWM, LOW);
      Serial.println("AZIMUTH MOTOR MOVES CLOCKWISE");
      Serial.println("   ");
    }
    else // if average light sensor values on right side are greater than on left side, azimuth motor rotates counterclockwise
    {
      digitalWrite(ALEN, HIGH); analogWrite(ALPWM, 255);
      digitalWrite(AREN, HIGH); digitalWrite(ARPWM, LOW);
      Serial.println("AZIMUTH MOTOR MOVES COUNTERCLOCKWISE");
      Serial.println(" ");
    }
  }
  else if (-1 * TE < dh || dh < TE) // if difference is smaller than tolerance, stop azimuth motor
  {
    digitalWrite(AREN, LOW); digitalWrite(ALEN, LOW);
    Serial.println("AZIMUTH MOTOR STOPS");
    Serial.println(" ");
  }

  if (-1 * TE > dv || dv > TE) // check if the difference in top/bottom light sensors is greater than tolerance
  {
    if (avt > avd) // if average light sensor values on top side are greater than on bottom side then elevation motor rotates clockwise
    {
      digitalWrite(EREN, HIGH); analogWrite(ERPWM, 255);
      digitalWrite(ELEN, HIGH); digitalWrite(ELPWM, LOW);
      Serial.println("ELEVATION MOTOR MOVES CLOCKWISE");
      Serial.println(" ");
    }
    else // if average light sensor values on bottom side are greater than on top side then elevation motor rotates counterclockwise
    {
      digitalWrite(ELEN, HIGH); analogWrite(ELPWM, 255);
      digitalWrite(EREN, HIGH); digitalWrite(ERPWM, LOW);
      Serial.println("ELEVATION MOTOR MOVES COUNTERCLOCKWISE");
      Serial.println(" ");
    }
  }
  else if (-1 * TE < dv || dv < TE) // if difference is smaller than tolerance, stop elevation motor
  {
    digitalWrite(EREN, LOW); digitalWrite(ELEN, LOW);
    Serial.println("ELEVATION MOTOR STOPS");
    Serial.println(" ");
  }
  else if (abs(EA) > 70)
  {
    digitalWrite(EREN, LOW); digitalWrite(ELEN, LOW);
    Serial.println("ELEVATION MOTOR STOPS");
    Serial.println(" ");
  }
  delay(DT);
}

void recvWithStartEndMarkers() {
  static boolean recvInProgress = false;
  static byte ndx = 0;
  char startMarker = '<';
  char endMarker = '>';
  char rc;

  while (HC12.available() > 0 && newData == false) {
    rc = HC12.read();

    if (recvInProgress == true) {
      if (rc != endMarker) {
        receivedChars[ndx] = rc;
        ndx++;
        if (ndx >= numChars) {
          ndx = numChars - 1;
        }
      }
      else {
        receivedChars[ndx] = '\0'; // terminate the string
        recvInProgress = false;
        ndx = 0;
        newData = true;
      }
    }

    else if (rc == startMarker) {
      recvInProgress = true;
    }
  }
}

//=====================================================================

void parseData() {  // split the data into its parts

  char * strtokIndx;  // this is used by strtok() as an index

  strtokIndx = strtok(tempChars, ",");    // get the first part - the string
  TL = atoi(strtokIndx);    // convert this part to an integer

  strtokIndx = strtok(NULL, ","); // this continues where the previous call left off
  BL = atoi(strtokIndx);

  strtokIndx = strtok(NULL, ",");
  TR = atoi(strtokIndx);

  strtokIndx = strtok(NULL, ",");
  BR = atoi(strtokIndx);
  
  strtokIndx = strtok(NULL, ",");
  EA = atof(strtokIndx);

}

//=======================================================================

void showParsedData() {  // shows parsed data in serial monitor output of PC
  Serial.println("<TL,BL,TR,BR,EA,DT,TE>");
  Serial.print("<");
  Serial.print(TL);
  Serial.print(",");
  Serial.print(BL);
  Serial.print(",");
  Serial.print(TR);
  Serial.print(",");
  Serial.print(BR);
  Serial.print(",");
  Serial.print(EA);
  Serial.print(",");
  Serial.print(DT);
  Serial.print(",");
  Serial.print(TE);
  Serial.print(">");
  Serial.println();
  Serial.println();
}

Hello everyone,

I am currently trying to connect 2 ESP32 via BLE by using the examples from this library : https://github.com/nkolban/ESP32_BLE_Arduino I have set up one ESP32 as a server which contain some data that can be read by the ESP32 that I set up as a client but it doesn't work. Have you found a solution ?

Thanks in advance.

I would also like an answer to this question if anyone has figured it out yet.

trying: Hello everyone,

I am currently trying to connect 2 ESP32 via BLE by using the examples from this library : https://github.com/nkolban/ESP32_BLE_Arduino I have set up one ESP32 as a server which contain some data that can be read by the ESP32 that I set up as a client but it doesn't work. Have you found a solution ?

Thanks in advance.

That code works fine for me.