function setBatteryLevel() in BLEHIDDevice.cpp is invalid

[BG2CRW]

Board

ESP32 DevModule

Device Description

a ble keyboard use ESP32 DevModule

Hardware Configuration

BLE Server

Version

v2.0.2

IDE Name

arduino ide

Operating System

win10

Flash frequency

40MHz

PSRAM enabled

no

Upload speed

921600

Description

BLEHIDDevice hid;
hid->setBatteryLevel(level);

esp32实现的蓝牙键盘(server 模式)，用这种方法进行电量设置，在win10系统下显示键盘电量。
在初次连接时，电量显示正常，电量也可变化。但是断开连接后重新连接，电量始终显示为初次连接时的电量，且更改变量赋值后，win10系统显示变量仍然无变化。

I want to use this way to make my BLE keyboard change battery level in win10. but it is invalid.
When I connect my keyboard first time, it is work, meanwhile, win10 can show my real-time battery level.
but after disconnect and reconnect, win10 can only show its last battery level, and can't show my realt-ime battery level, when I change my battery level variable.

Sketch

BLEHIDDevice hid;
hid->setBatteryLevel(level);

I use this library https://github.com/T-vK/ESP32-BLE-Keyboard, it is also mentioned by T-vK/ESP32-BLE-Keyboard#99

Debug Message

no debug message

Other Steps to Reproduce

No response

I have checked existing issues, online documentation and the Troubleshooting Guide

• I confirm I have checked existing issues, online documentation and Troubleshooting guide.

[BG2CRW]

I find this page #4517, it seems to deal with this bug, but I think it doesn't work

[BG2CRW]

oh, I fix this bug, in BLEHIDDevice.cpp #45

this is origon:

BLE2904* batteryLevelDescriptor = new BLE2904();
batteryLevelDescriptor->setFormat(BLE2904::FORMAT_UINT8);
batteryLevelDescriptor->setNamespace(1);
batteryLevelDescriptor->setUnit(0x27ad);

m_batteryLevelCharacteristic = m_batteryService->createCharacteristic((uint16_t) 0x2a19, BLECharacteristic::PROPERTY_READ | BLECharacteristic::PROPERTY_NOTIFY);
m_batteryLevelCharacteristic->addDescriptor(batteryLevelDescriptor);
m_batteryLevelCharacteristic->addDescriptor(new BLE2902());

this is my fix:

BLE2904* batteryLevelDescriptor = new BLE2904();
batteryLevelDescriptor->setFormat(BLE2904::FORMAT_UINT8);
batteryLevelDescriptor->setNamespace(1);
batteryLevelDescriptor->setUnit(0x27ad);

m_batteryLevelCharacteristic = m_batteryService->createCharacteristic((uint16_t) 0x2a19, BLECharacteristic::PROPERTY_READ | BLECharacteristic::PROPERTY_NOTIFY);
m_batteryLevelCharacteristic->addDescriptor(batteryLevelDescriptor);
m_batteryLevelCharacteristic->addDescriptor(new BLE2904());

[mrengineer7777]

arduino-esp32/libraries/BLE/src/BLEHIDDevice.cpp

Line 45 in 0b3f1a9

m_batteryLevelCharacteristic->addDescriptor(new BLE2902());

Looks like you've found a possible bug. Changing from new BLE2902() to new BLE2904() causes it to work?

[BG2CRW]

arduino-esp32/libraries/BLE/src/BLEHIDDevice.cpp

Line 45 in 0b3f1a9

m_batteryLevelCharacteristic->addDescriptor(new BLE2902());

Looks like you've found a possible bug. Changing from new BLE2902() to new BLE2904() causes it to work?

yes, it works. I don't know why. I only think it should same as "BLE2904* batteryLevelDescriptor = new BLE2904()"

[SuGlider]

@BG2CRW Thank you for reporting and investigating it!

I think it is neessary to investigate the issue.

Descriptor 0x2904 aka "Characteristic Presentation Format" is already added by Line 44.

Line 45 adds another Descriptor 0x2902, which is the notify descriptor - necessary for notifying Win10 that the value has changed.

[BG2CRW]

I’m looking forward to the right code.