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WICED Smart Bluetooth

Anonymous
Not applicable

Hi Sir,

I want to ask if there any size limitation if I use the custom notify function?

The following photo is an experiment of the 80 bytes data but I'm not sure if any limitations.

screenshot.png

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1 Solution
Employee

Currently, the MTU size is 23 bytes, so you can notify up to at 20 bytes. If you have to notify more than this, you can break it up into multiple characteristics or notify with the same handle, but with different chunks of data and let the client reassemble them.

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Employee

Currently, the MTU size is 23 bytes, so you can notify up to at 20 bytes. If you have to notify more than this, you can break it up into multiple characteristics or notify with the same handle, but with different chunks of data and let the client reassemble them.

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Employee

Please note that this is a limitation of the Bluetooth spec.  The maximum value that can be indicated is 20 bytes.  After client has received notification it can use Read Blob procedure to read rest of the bytes.

Anonymous
Not applicable

Thanks, is there any example for the Read Blob procedure you mention?

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Employee

Server application does not need to do anything to support Read Blob. Read Blob as well as Read is processed by the stack. Make sure that you copy the value that you want to deliver to the client to the GATT database (bleprofile_WriteHandle) before sending notification. Check long_characteristic sample in the latest SDK.

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Anonymous
Not applicable

May I confirm you mean the latest SDK is SDK1.1 or the SDK2.1.1? I'm working on the BCM20732 now does it support?

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Employee

I would definitely recommend to switch to the latest. There might be some problems with long characteristics in 1.x.

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