Sending text data over a Bluetooth HC-08 module


I have made this Bluetooth BLE app for my Android phone to send some data over my Bluetooth module to an Arduino. It works great, but if I will send some text with this app, it sends only 20 characters and after that the rest of the data seems to be lost. I only receive about 20 characters and after that it is finished. Only the short data like the 0T92 or 0T1 I am sending the Arduino will receive. What is wrong or what can I make to send all the text I write in the text box for sending it?
Here is the app with the blocks:

I can not take a picture of the whole app. If that is needed, I will try to post a picture from the computer at home.



Nobody? If somebody has an example or can tell what to do to get it sending text that is more than 20 characters long, I would appreciate it.

I have found an example of splitting the text and make a list, but it does not works:

Any ideas/help what is wrong and why I can not send text that is longer than 20 characters?

I can send the text by splitting it! I have used the old app on my mobile phone because this was on the main screen and the new installed one was still in the menu :roll_eyes:

Now, I have fixed an issue I had in the previous post I have made here. It works perfectly now!

If someone helps, here it is:



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Well done Stef. Interesting conversation you were having with yourself there :grin:

The reason you cannot send more than 20 characters is that the BLE data packet size defaults to approx 32 bytes, including it's own header & footer. So yes, a good way to work with that is to send your text via several packets. You can, depending on the receiving device, increase the MTU (Maximum Transmission Unit), up to a maximum of 247 bytes (Both devices must support BLE v4.2 - v5.0).

You can find the Blocks to make that happen in the BLE Extension:
ble mtu

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(added to FAQ)

Hi Chris,

Thanks! Yes, that is really funny this conversation :grin: I agree with you!
To change the MTU size I have tried, but that does not works (The HC 08 module it is a BLE 4.0 device as I know it!). Any way, I think, that is the better option to solve it and it is workable for more cases.

Thanks again and regards


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