BT Classic communication between two ESP32

Posts: 1
Joined: Fri May 11, 2018 10:34 am

BT Classic communication between two ESP32

Postby Crisos » Fri May 11, 2018 11:24 am

Hi Everyone,

I have a very simple application where one ESP32 sends a message over BT to another ESP32. I have been playing mostly with Arduinos till now and using that this kind of application was quite easy, but now I want to move to this platform.

Using BluetoothSerial.h library I can happily connect to an Android device and send those messages, but I can't start the connection from another ESP32. This library doesn't have a connect command, so I went and found out what is the control to connect via SPP and I seem to be able to find the other device and connect to it, but also seems like the connection crashes immediately afterwards.

Here the code I am using:

Code: Select all

#include "esp_bt_main.h"
#include "esp_gap_bt_api.h"
#include "esp_spp_api.h"
#include <BluetoothSerial.h>

uint8_t address[6] = {0x30, 0xAE, 0xA4, 0x21, 0xBA, 0xBA};
String MACadd = "30:AE:A4:21:BA:BA";

static const esp_spp_sec_t sec_mask = ESP_SPP_SEC_NONE;
static const esp_spp_role_t role_slave = ESP_SPP_ROLE_MASTER;
esp_err_t connHan;

BluetoothSerial SerialBT;

void setup() {
  Serial.println("The device is ready!");
  SerialBT.begin("Glove ESP");
  Serial.println("Looking for device...");
  if(esp_spp_start_discovery(address) == ESP_OK){
    Serial.println("Device found!");
    Serial.println("Device not found :(");
  connHan = esp_spp_connect(ESP_SPP_SEC_NONE, ESP_SPP_ROLE_MASTER, 3,address);
  if(connHan == ESP_OK){
    Serial.println("Device Connected!");
    Serial.println("Device not connected :(");
  if (SerialBT.hasClient() == true) {
        Serial.print("Client connected");
        //SerialBT.println("some text");
    } else {
        Serial.println("Client disconnected");
        SerialBT.begin("Glove ESP");
void loop() {

I tried with different SCN, but all the time I get this message: (not sure why it is not clear, like wrong baud)

Code: Select all

C'΂⸮⸮Θb⸮⸮`<⸮!⸮The device is ready!
Looking for device...
Device found!
Device Connected!
E (1520) BT: btm_sec_connected

E (1545) BT: l2cu_adjust_out_mps bad packet size: 0  will use MPS: 0
E (1554) BT: process_service_search_attr_rsp

E (1604) BT: port_rfc_closed RFCOMM connection in state 1 closed: Closed (res: 19)
Client disconnected
E (2146) BT: btc_spp_disconnect unable to find RFCOMM slot! disconnect fail!
E (2146) BT: JVenable fails

Anyone can help? I have spent like two days on this and I couldn't imagine it could be so complicated!
Thank you in advance!

Posts: 1
Joined: Sun May 13, 2018 4:00 pm

Re: BT Classic communication between two ESP32

Postby PeterWay » Sun May 13, 2018 4:06 pm


i will add at this topis my question.

I like to use BT classic commninication.
At first im loking for Arduino example for search classic BT equ. near.
Second i like to make pair od them and serial cimmunication over.

Im loking and searcing all google, but i found only examples for BLE.

TNX for help and answer


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