Unable to write attribute about blewinrtdll

[StevenDextrain]

Ah nevermind, I just realized I missed part of the first (and most important part of your reply 🙃), I'm gonna try that and come back with another question, or hopefully, everything will work fine and I'll close the issue !
Thanks again !

[adabru]

Hi @StevenDextrain :-)

you only subscribe to characteristics that issue notify events. After subscription you can read incoming messages with PollData.

You can write to characteristics without prior subscription.

"ReadCharacteristic" is not implemented in the dll although it is a ble functionality. If you need it you can checkout #6 (comment) . But subscribing alone might be sufficient for you.

[StevenDextrain]

Hey again !
Thanks for so quick of a response 😁
I'm wondering what you mean by "But subscribing alone might be sufficient for you.", is there already a way to collect my device's data without implementing ReadCharacteristic ?

[StevenDextrain]

Hello again,

It doesn't work (yet), and I noticed that the BleApi.SendData(in data, false) method call returned "false".
I was wondering if it meant that there was an issue while sending the data or if I'm totally misled...
Follow-up question, PollData is used to read what the device is sending constantly, right ?
I'm sorry about all of these questions, but I've never programmed in C++, and I've also never had to work with hardware before 🙃 (So you're basically my only hope)

Thanks again, and have a nice day !

[adabru]

BleApi.SendData(in data, false) method call returned "false".

For the non-blocking call, the result is always false:

BleWinrtDll/BleWinrtDll/BleWinrtDll.cpp

Lines 554 to 560 in f2635b7

	bool result = false;
	// copy data to stack so that caller can free its memory in non-blocking mode
	SendDataAsync(*data, block ? &signal : 0, block ? &result : 0);
	if (block)
	signal.wait(lock);
	return result;

You should see an error in the message window eventually, if it doesn't succeed. The blocking call returns true on success of sending:

BleWinrtDll/BleWinrtDll/BleWinrtDll.cpp

Lines 537 to 540 in f2635b7

	if (status != GattCommunicationStatus::Success)
	saveError(L"%s:%d Error writing value to characteristic with uuid %s", __WFILE__, __LINE__, data.characteristicUuid);
	else if (result != 0)
	*result = true;

The success doesn't guarantee that the package arrives at the target device though. There is a possibility to do that though.

PollData is used to read what the device is sending constantly, right ?

Exactly:

SubscribeCharacteristicAsync

BleWinrtDll/BleWinrtDll/BleWinrtDll.cpp

Line 492 in f2635b7

subscription->revoker = characteristic.ValueChanged(auto_revoke, &Characteristic_ValueChanged);

Characteristic_ValueChanged

BleWinrtDll/BleWinrtDll/BleWinrtDll.cpp

Line 478 in f2635b7

dataQueue.push(data);

PollData

BleWinrtDll/BleWinrtDll/BleWinrtDll.cpp

Lines 520 to 524 in f2635b7

	if (!dataQueue.empty()) {
	*data = dataQueue.front();
	dataQueue.pop();
	return true;
	}