ESP32とAndroidのBlueTooth接続がすぐ切れてしまう

Question

前提・実現したいこと

Androidのセンサーの値をESP32にBlueToothで送信したい

発生している問題・エラーメッセージ

ESP32がBlueToothの接続候補として出現してつなぐと5秒程度で接続が切れ，以前接続したデバイスという扱いになってしまう

該当のソースコード

#include "BluetoothSerial.h"

BluetoothSerial SerialBT;

void setup() {
  Serial.begin(115200);
  SerialBT.begin("ESP32test");
}

void loop() {
  if (Serial.available()) {
    String sendData = Serial.readStringUntil(';');
    SerialBT.print(sendData);
  }

  if (SerialBT.available()) {
    String receiveData = SerialBT.readStringUntil(';');
    Serial.print(receiveData);
  }
}

試したこと

以下の記事を参考に電池の最適化を切ったが挙動は変わらなかった．
https://investinlife.tokyo/kaki/bluetoothmidiservice/

また，AndroidとESP32どちらに問題があるのか不明であったためそれぞれBlueToothでPCと接続してみたところ両者問題なく接続できることを確認しました．

補足情報（FW/ツールのバージョンなど）

Pixel4 Android11

Answer 1

回答というにはナンですが、別件でArduino ESP32の修正履歴を見ていたら、ボードパッケージ1.0.5と1.0.6の間でBluetoothまわりがちょこちょこといじられているようです。内容は見ていませんが、最新版で試す(あるいは逆に古いバージョンを試す)とどうなるでしょうか。

commit 9a0762ad2a3773ccf919631203aa24cd311109a0
Author: Me No Dev <[e-mail]>
Date:   Wed Mar 17 18:46:55 2021 +0200

    [BLE Client] Fix Deadlock when calling writeValue after registerForNotify

    Fixes: https://github.com/espressif/arduino-esp32/issues/4952

commit d362e1ee1adeb6c5e4980457de8c3612235feea4
Author: Raúl C.G <[e-mail]>
Date:   Tue Mar 16 10:56:23 2021 +0100

    [BLE] Allows you to specify which channels are used to advertise. (#4954)

    In some use cases getting rssi signal from one channel is more stable (less variance) than rssi from the three advertising channels.

    This change allows you to specify which channels are used to advertise.

commit 5b845272ed5357a3ef4ca0d118a21e995d69b047
Author: me-no-dev <[e-mail]>
Date:   Tue Mar 16 02:11:59 2021 +0200

    Fix BluetoothSerial TX Stall

    Fixes: https://github.com/espressif/arduino-esp32/issues/4949

commit 4d95e3a7ea072ac61ff0eb24b3304db47de96712
Author: me-no-dev <[e-mail]>
Date:   Tue Mar 9 01:56:47 2021 +0200

    Fix BT not starting correctly and SPP Coex not working

    Fixes: https://github.com/espressif/arduino-esp32/issues/4912

commit bd3addeb8e9b05766979caf32b74ee0a0e2ae4c8
Author: Aron Rubin <[e-mail]>
Date:   Mon Mar 1 16:55:04 2021 -0500

    Fixed use of Bluedroid instead of BT in HAL. (#4879)

    Fixed use of CONFIG_BLUEDROID_ENABLED instead of CONFIG_BT_ENABLED in HAL. This prevented compilation with Nimble-only configuration without apparent benefit.

commit 44aaf13225e349f75f63fdcc059940f451844c02
Author: Bascy <[e-mail]>
Date:   Mon Feb 22 18:37:07 2021 +0100

    Added BLEAddress operator overload methods (#4839)

    Allows BLEAddress to be used as key in std::map etc

commit 1ab550f6f27ac8245fc9f0ee2f076329ba9ad457
Author: Michael <[e-mail]>
Date:   Tue Feb 16 21:10:04 2021 +0100

    Changed BLE notify_callback from raw function pointer to std::function (#4737)

commit 9be784f69b696d5bbb189a2fe5f1750ce2855426 (tag: 1.0.5-rc7)
Author: Emanuel Posescu <[e-mail]>
Date:   Tue Feb 16 11:21:45 2021 +0200

    Improve cleanup in BLEClient (#4742)

    - Remove client from the list of devices in case registration fails
    - Filter other events not related to registration during registration phase
    - Cleanup if connect fails
    - Reset if after disconnect
    - Disconnect callback *after* cleanup is done so object can be deleted

    This fixes some of the issues I had like:
    - `BLEClient::connect` hangs up and never recovered because registration failed
    - `BLEClient` could not be deleted after disconnect or deletion creating ghost events https://github.com/espressif/arduino-esp32/issues/4047
    - `BLEClient` could not be properly reused after a connection was attempted (successful or not)

    * Cleanup in case of registration and connect failure.
    Cleanup before calling disconnect callback for safe delete.
    Reject other events during registration.
    Adresses #4047, #4055

    * Clear if after unregister #4047

commit 7cdfb8bc7cdcb9e47931e28a65b7a587a721047b
Author: Markus Frey <[e-mail]>
Date:   Tue Feb 16 10:02:58 2021 +0100

    Refactor BLEAdvertisedDevice (#4739)

    fixes #4596

    * Prevent possible undefined behaviour by get methods not taking an index as parameter
    * Add methods to get the count of service data UUIDs and service UUIDs
    * Various code improvements

commit e831680a41d4c96769cae7277501ce41abe69eee
Author: ushiboy <[e-mail]>
Date:   Tue Feb 16 08:50:24 2021 +0900

    Fixed a memory leak in BLE (issue #4753) (#4761)

    * Fixed crash on delete after disconnect

    * Fixed memory leak when getting characteristics

    * Removed guard

    Co-authored-by: ushiboy <[e-mail]>

Comments

[thkana]

バージョン上げて解決したのかしら?