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CC85XX bidrectional with 2 pair of master/slave boards

Alan Walsh
Prodigy 40 points
Other Parts Discussed in Thread: CC8520

I am trying to use 2 pair of master and slave (4 boards) to allow bidrectional audio communication, 1 master and slave board on each end. However when i turn on the boards one of the master slave pair loses/has a flaky connection, led D9 starts blinking. Is this setup possible and if so do i need to change something in the network pairing to make it work?

  • 0
    TI__Expert 6825 points

    Hi Alan,

    How close are the master and slave antennas to each other on the "same end"?

     

    -P

  • 0 in reply to Per H
    Prodigy 40 points

    The boards are pretty much side by side on each end, so less than a foot.

  • 0 in reply to Alan Walsh
    TI__Expert 6825 points

    Does it improve if you move the boards apart?

     

    -P

  • 0 in reply to Per H
    Prodigy 40 points

    I don't really have much scope to move the boards apart as they will have to be placed in a box together. Do you think there is an issue with having the master so close to the slave of the other pair? Also do you know when the software will be updated to support bidirectional audio transmission on one board? Thanks for your help.

    Alan

  • 0 in reply to Alan Walsh
    TI__Expert 6825 points

    Hi Alan,

    Yes, it is possible that the devices are interfering with each other, if one device is transmitting while the other device is receiving. This interference can affect the performance even though they are using different RF channels. The selectivity of the radio says how large a interfering signal can be on another frequency while the radio is still capable of receiving on it’s own RF channel.

     -P

  • 0 in reply to Per H
    Prodigy 10 points

    I was planning the same type of build and was lead to believe it would work as the product was described as "Utilizing numerous coexistence mechanisms allows the CC8520 to avoid interfering with, or being interfered by other 2.4 GHz radio systems" and this video which put four units within the same 1-2 foot area: http://focus.ti.com/lit/ml/swrc202/swrc202.wmv

     

    Are there any settings or configurations that allow the CC8520 to avoid interfering with or being interfered with itself? Is there any way to encourage the CC8520 to select a particular frequency within it's frequency range that would be distant from a second unit? Does the addition of a signal booster (2510) magnify the problem? Is there any way to figure out how significant this problem would consistently be or would it depend on what else is operating in the area?

  • 0 in reply to David Jannke
    Prodigy 40 points

    Hi David,

    I tried the setup with the 4 boards all side by side and that worked, i was able to get audio reliably both directions. It was only when i started to move the alternate master/slave boards apart that i started to lose connection. In my opinion it is because the "interfering" master that is beside the slave swamps the paired master signal once you start to move the paired master further away and it's signal gets weaker. Just my two cents, would be nice to get a definitive answer from TI.

    Alan