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Adaptive Frequency Hopping using the CC2540DK

Sean McDonough
Prodigy 50 points

I am using the CC2540DK in coexistence testing. Using the SmartRF Studio 7 I'm able to get the devices to communicate with each other, but they don't seem to be frequency hopping. Is there some setting that needs to be changed so that they will hop frequencies or will I have to go into the programming and set something up there? Any guidance as to what to do would be helpful. 

  • 0
    Guru 18595 points

    Wow!

    Be sure if your BLE devices are communicating, the frequency hopping is taking place :) Bluetooth hops 1600 times per second. I have not worked with smartRF studio but frequency hopping is something inherent in Bluetooth, all communications perform it. It is inherent.

    On the other hand, Adaptive Frequency Hopping, is the ability of the chips of detecting busy frequency channels and try to avoid them. For example, if channels 21 to 25 are busy due to interferences, they are going to be considered in a pool of frequencies to avoid when hopping in the next channel map update.

    Bye!

  • 0 in reply to kazola
    Prodigy 50 points

    Thank you for the clarification that does help sort some things out.

  • 0 in reply to Sean McDonough
    Intellectual 625 points

    Hi,

    Please check this post. AFH is not implemented in BLE stack and as far as I understand it should be done as a master application.

    http://e2e.ti.com/support/low_power_rf/f/538/t/131676.aspx

  • 0 in reply to Sean McDonough
    Guru 18595 points

    I have not said AFH is implemented :)

  • 0 in reply to kazola
    Intellectual 625 points

    Yes, I see. I just wanted to remind this for other readers :) On the other hand, I really wonder how to build this feature in applications. Do you know or have you seen any kind of profile examples or block of codes that has this feature? 

  • 0 in reply to Cagatay Ulusoy
    Guru 18595 points

    Haven't!

    I guess this could be interesting in very crowded environments. Some time ago I worked with Bluegiga WT12 modules, which featured a CSR04 core with AFH, and I did not observe much difference.

    Bye!

  • 0 in reply to kazola
    Prodigy 50 points

    I think I worded my question incorrectly. Your response has helped me  understand the theory more, but after additional testing I am having the same results. The SmartRF Studio 7 allows for the cc2540DK_EM boards to be used as either a transmitter or receiver. The channel is set before the connection begins and it has been confirmed from several test that it stays on that channel instead of hopping. A brief overview of why I came to this conclusion. Using a signal generator at the decided frequency the packet received rate drops off to nothing. In addition a spectral analyzer was used and the only activity was at the one channel as opposed to seeing activity over the entire channel. Changing the specified channel moved the location of the activity on the spectral analyzer accordingly. 

    Also traditional Bluetooth hops at 1600 times per second. BLE is a little bit different in that you are able to change the connection interval from 7.5ms to 4 s. I believe the change in protocol is so that it will use less power. 

    The Studio 7 interface useful for the testing that I need to do but I need it to be hopping. Is there something I need to change on the boards? Some guidance would be appreciated. 

  • 0 in reply to Sean McDonough
    Prodigy 50 points

    Has anyone had a chance to look this over? I am still running into the same problem.