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BLE 5 compatibility with smartphones having BLE 4.0

Hie,

Is it compulsary for us to send only 20 bytes of data or less than that in one packet in BT5 as we used to do it in BT4 to make BT5 compatible in communicating with smartphones having BT4.

Thank You.

Regards Deepak

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  • Hi,

    BT4.0 indeed supports PDU length extension (on Link Layer) as well as MTU extension on ATT/GATT layer. The fact that we all stick to default ATT_MTU size of 23B (from which 3 bytes are "eaten" by GATT header overhead) is just the way we deal with the fact that many deices (as well as Nordic stacks!) haven't supported these features originally. All these concepts (PDU and MTU extensions) are indeed valid in BT5.0 so there is no problem to be backward compatible (= support features from BT5.0 but by default use "legacy" modes to support connection with devices supporting only older BT versions).

    Cheers Jan

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  • Hi,

    BT4.0 indeed supports PDU length extension (on Link Layer) as well as MTU extension on ATT/GATT layer. The fact that we all stick to default ATT_MTU size of 23B (from which 3 bytes are "eaten" by GATT header overhead) is just the way we deal with the fact that many deices (as well as Nordic stacks!) haven't supported these features originally. All these concepts (PDU and MTU extensions) are indeed valid in BT5.0 so there is no problem to be backward compatible (= support features from BT5.0 but by default use "legacy" modes to support connection with devices supporting only older BT versions).

    Cheers Jan

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