Reason for xTaskCreate in BleKeyboard::begin()?

[sivar2311]

Hello T-vK!

I have forked your library to switch to the NimBLE-Arduino library to save memory.
While editing I noticed that in the BleKeyboard::begin() function xTaskCreate is used.
In the fork I removed this extra task and the library works fine.

I wonder what is the reason for this extra task?
Can you explain it to me in more detail?

[sivar2311]

No idea? 🙁

[T-vK]

I can't recall, but xTaskCreate shouldn't be necessary at all. A long time ago in #53 this has already been shown. But I couldn't merge it yet because it contains a breaking change.

[sivar2311]

Hello T-vK! Thank you for your reply. 🙂
xTaskCreate has been used since the initial commit.
Maybe it was necessary at that time with the BLE stack.
I am still quite inexperienced when it comes to BLE. Hence my question.

[sivar2311]

I would like to continue this discussion and therefore reopen this topic.

The same issue seems to affect pull request #107 and other pending improvements.
As far as I can see, the original problem seems to be that (sometimes) after a disconnect, advertising does not restart automatically? (Please correct me if I am wrong.)

I have changed my fork so that the BleKeyboard class inherits from BleServerCallbacks and BleCharacteristicCallbacks and the corresponding callbacks are implemented directly in the BleKeyboard class.

This would allow to use the onDisconect callback to restart the advertising automatically - without requiring any changes to the code on the user side.

[T-vK]

@sivar2311 That sounds really great! I haven't looked at it yet, but you should probably make a Pull Request for this. I think this change would solve a lot of problems!

[sivar2311]

I don't think a pull request is a good idea.
The original reason for my fork was to switch to the NimBLE-Arduino library, which my fork includes accordingly.
So a PR would do more harm than good.

Maybe @dvv could implement this in his fork and do the pull request?

[T-vK]

Maybe we can add an option to choose between NimBLE-Arduino and the other BLE library. If the API is the same, we should be able to use something like that:

#if defined(USE_NIM_BLE)
  #include <NimBLEDevice.h>
  #include <NimBLEServer.h>
  #include <NimBLEUtils.h>
  #include "NimBLEHIDDevice.h"

  BLEDevice = NimBLEDevice;
  BLEServer = NimBLEServer;
  BLEHIDDevice = NimBLEHIDDevice;
  BLESecurity = NimBLESecurity;
  BLEServerCallbacks = NimBLEServerCallbacks;
  BLECharacteristicCallbacks = NimBLECharacteristicCallbacks;
  BLECharacteristic = NimBLECharacteristic;
#else
  #include <BLEDevice.h>
  #include <BLEServer.h>
  #include <BLEUtils.h>
  #include "BLE2902.h"
  #include "BLEHIDDevice.h"
#end

So that the user can just say #define USE_NIM_BLE to the NimBLE libraries.

[sivar2311]

That's a good idea.
I will try to implement that.

[sivar2311]

Okay, done...that was actually quite easy...
...but there is a problem with the NimBLE version that I hadn't noticed before: Only 8 bytes ("Hello wo") are sent at once instead of "Hello world...".

I suspect it has to do with the MTU, but my knowledge of BLE is not yet sufficient. I will try to solve the problem.

Maybe you have an idea? (https://github.com/sivar2311/ESP32-NimBLE-Keyboard)

[T-vK]

The reason could be that NimBLE is "too" fast. Some applications have trouble receiving mare than x key events per second. See #88 and #92

[sivar2311]

Yes, you are right! 👍

vTaskDelay(1) inside sendReport does the trick :)