ESP32 Forum

Posted: **Mon Sep 06, 2021 2:10 pm**

This is a follow up on basically the same problem, which I first had assumed was a problem in the Arduino framework layer for the ESP32 and thus posted in that forum. Not so, and apologies for the more or less Double Post. TL:DR:

The ESP32 device does not show up on Chromebook as pairable device
Environment: ESP32, PlatformIO, IDF framework
Keywords: Bluetooth, SerialBT, Pairing
Example code snippet: bt_ssp_acceptor as included in the IDF repository

A bit more verbose:

ESP_SPP_ACCEPTOR shows up in i.e. Android (and Windows) as a pair-able device.

On ChromeOS, it doesn't show up at all. At first I thought this was a limitation of ChromeOS, but this is (at least partly) not the case: if I spin up another serial Bluetooth classic device, ie a KONNWEI ELM327 dongle, it does show up on ChromeOS and will pair.

A hint could be that on Android, the icon in front of the ESP32 ESP_SSP_ACCE{TOR is best described as a screen with a horizontal line below it, like an open laptop. The KONNWEI ELM327 dongle has a different icon, and is best described as a screen with a mobile phone (or desktop PC?) in front of it.

Given the different icons I assume it must have to do with different advertising. I know, not the correct nomenclature for classic. I admit I can't find any good table what these icons in front of each BT device in Android actually mean.

Any hints? Of course if I need to provide more info I am happy to do so.

Thank you.

Posted: **Sat Nov 20, 2021 7:53 pm**

Hi

I think you need to set the Bluetooth Class Of Device to something Chrome OS will accept.

In the Espressif arduino-esp32 code it is done in BluetoothSerial.cpp, line 636:
See https://github.com/espressif/arduino-es ... Serial.cpp

Code: Select all

    // the default BTA_DM_COD_LOUDSPEAKER does not work with the macOS BT stack
    esp_bt_cod_t cod;
    cod.major = 0b00001;
    cod.minor = 0b000100;
    cod.service = 0b00000010110;
    if (esp_bt_gap_set_cod(cod, ESP_BT_INIT_COD) != ESP_OK) {
        log_e("set cod failed");

I have tried to change the above to:

Code: Select all

    cod.major = 0b00101;
    cod.minor = 0b000000;
    cod.service = 0b00000010000;

This allowed ChromeOS to see my device in the Bluetooth menus, and I was able to pair with it.

Best regards
Brian

ESP32 Forum

BT classic serial does not show up on Chromebook as pairable device

BT classic serial does not show up on Chromebook as pairable device

Re: BT classic serial does not show up on Chromebook as pairable device