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Original question:

CC2650: Does Carrier-sense multiple access(CSMA) technique is implemented for Bluetooth?

Is it possible to send BLE advertisement packets on data channels?

Kainat Altaf
Prodigy 90 points

Is it possible to send BLE advertisement packets on data channels? If no, then why? 

  • 0
    Prodigy 215 points

    For legacy advertising, advertiser commands don’t support it because the spec doesn’t allow it. In Bluetooth 4.x LE, only advertising channels (37-39) can be used for advertising, and scanners will only listen for advertisers on these channels.

    Bluetooth 5 brings major improvements to advertising, commonly referred to as extended advertising. Short advertisements broadcast on channels 37-39 (primary advertising channels) can contain auxiliary pointers specifying the (secondary advertising) channel and start time for a longer auxiliary advertising packet containing up to 255 bytes of advertising data (or more when chaining is used). The secondary advertising channels in Bluetooth 5 are the data channels.

  • 0 in reply to Sultan Khan
    Prodigy 90 points

    Does this also means we cannot increase the advertisement packet size in BLE 4.x from 62Bytes? 

  • 0 in reply to Kainat Altaf
    Prodigy 215 points

    The limit for BLE 4.x advertisements is 37 bytes. If you transmit advertisements longer than that, BLE 4.x devices will ignore/reject them.

    Part of the reason for this is that channels 37-39 are used for advertising by all devices, so it’s important to keep advertisements short to avoid “hogging the airwaves” and allow many BLE devices to coexist.