Bluetooth text message limit?

MIT App Inventor Help
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First post so sorry if this isn’t the right place to post.
I have a problem trying to send a large comma delimited text file (32k) using classic Bluetooth where it seems only the first 1,000 characters get sent. I can receive and store the full 32k without problem so my question is, is there some kind of output buffer that’s causing the limiting? Any help would be appreciated.

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I do not understand what you mean but maybe you are right :smiley: :+1:

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Have you searched for “Bluetooth text message limit?” On Google

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or youtube

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Thanks Salman, I’ve been searching for a couple of days but not found anything but your suggestion immediately just brought up some info that I hadn’t seen before and it does confirm that the maximum is 998 Bytes due to the data being broken down into smaller packets. Knowing this, I can quite easily rewrite my code to use a lot of smaller files rather than just one large one.
Thanks again.

Bill :slight_smile:

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Okay thanks for the information @Bill_Green Good Job :+1: :smiley: :+1:

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Hello Bill

Depends where your file is going - if to your own device/software than you can send chunks of data and assemble them into a file at the receiving end.

If you can use BLE instead of Classic, and again have control of both ends of the comms, you may be able to increase the MTU on the receiving device and send the whole file at once.

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Here we have examples of sending files by classic Bluetooth.

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Thanks Chris that’s exactly what I’m doing just now. It’s basically working but messing up somewhere along the line, I don’t know why just yet but I can work on it. One thing I don’t quite understand is that having broken the file into chunks (100 chrs) with a for next loop, sometimes there are very sizeable delays between some of the received chunks. Not really a problem just curious to know why that should be. Anyway I’ll push on and get it sorted. It’s going to an esp32 BTW.
Regards
Bill

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Hi Bill

Might depend on where you are - microcontrollers can get very hot and if they do, they slow down. Try attaching a small fan.

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No it’s the other way round Chris, The ESP32 is very fast so I’m actually waiting for the packets to arrive. Some arrive almost back to back while others can have several hundred ms between them. 44k bytes of text takes about six seconds but it’s a once a day routine so not a big issue.
Regards
Bill

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I see, the sending device then, or the esp32 is behind a bunch of obstacles or your setup is close to transmission distance maximum (or a combination of the three).

If you find you need help sleeping, visit my website:
https://www.professorcad.co.uk/appinventortips#TipsBluetooth

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Chris maybe if I slept a bit better I wouldn’t be making so many schoolboy errors. Found multiple mistakes at both ends but clearly not all of them but it’s getting there!
Nice comprehensive website BTW
Regards
Bill

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