[Interest] Qt Bluetooth Low Energy set a maximum MTU

Alex Blasche alexander.blasche at qt.io
Fri Nov 20 08:04:11 CET 2020

Hi Simon

What I meant is that if you *request* a certain max MTU size of 240 bytes, the other side might still reject it by responding with an even smaller MTU size response. It's the difference between "set" and "request".

Having said all that I can see where the ability of requesting 240 might help your particular use case and no there is no public API. You have to hack QtBluetooth or write a small Java section setting the value.


From: Simon FEUTRIER <sfeutrier at bluegriot.com>
Sent: Thursday, 19 November 2020 16:57
To: Alex Blasche
Cc: Qt Interest
Subject: Re: [Interest] Qt Bluetooth Low Energy set a maximum MTU

Hi Alex,

Thank you for your reply.
I'm a bit lost. It means you can never say : "for this exchange I want only packets of size 50 because it is relevant for my use case" ?


Le jeu. 19 nov. 2020 à 16:53, Alex Blasche <alexander.blasche at qt.io<mailto:alexander.blasche at qt.io>> a écrit :
Hi Simon,

there is no way to force a certain MTU size via the QT API. AFAIR you cannot force it anyway as both sides can make requests but not demands.


From: Interest <interest-bounces at qt-project.org<mailto:interest-bounces at qt-project.org>> on behalf of Simon FEUTRIER <sfeutrier at bluegriot.com<mailto:sfeutrier at bluegriot.com>>
Sent: Thursday, 19 November 2020 09:09
To: Qt Interest
Subject: [Interest] Qt Bluetooth Low Energy set a maximum MTU


Do you know if it is possible to set the MTU from the Qt side ? I am receiving bluetooth messages of size between 240 and 244 (max payload) (by notify). I would like to receive only messages of size 240. Is this possible ?

Best regards,

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