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BLE Advertising Channels with CC2540

Chris Read
Genius 3345 points

I am working on a application derived from the SimpleBLEBroadcaster sample application, and wanted to understand more about how the libraries handle the three BLE advertising channels.

Does the TI BLE protocol stack automatically advertise on all three BLE advertising frequencies that are available each time it enters GAPROLE_ADVERTISING mode?

alternatively...

Does it switch to GAPROLE_WAITING in between each frequency change?

I have read e2e postings that indicate that the shortest advertisement is 128 microseconds.  Is that for all three frequencies, or is that for a single frequency?

  • 0
    Guru 22270 points

    Hello Chris,

    Getting all the details about the library won't be easy.  I would recommend looking at the Bluetooth Specification V4.0. Vol6, chapter 4 section 4.4 page 57.(page 2221)  Also, you can search for the Creating Android Apllications for Today's Bluetooth Devices, (BEST ONE) as well as the BLEwiki. Plus the http:developer.android.com

    This describes the advertising states for the 4 different advertising event.

    Also, you can use Packet Sniffer and see how it behaves during advertising.

    The controller advertises on all three channels with a delay between each channel change, they are not sent simultaneously.  The controller can only be in one state at a time.  From the code comment for the GAPROLE_WAITING  it only enters that state when the link was terminated.  If your application needs to know every GAPROLE state, then this is the area to put you code.  On your external device (Android I assume), there are functions that allow you to see each state the device is in.

    Hope that helps,

  • 0 in reply to Greenja
    Genius 3345 points

    Thanks for your suggestions, greenja.