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CC2540 random disconnect. Is it normal?

Arvydas Sidorenko
Prodigy 110 points

Other Parts Discussed in Thread: CC2540

1)

I leave the keyfob connected to mac and I see that it gets some random disconnects once in a while, like once in an hour. It connects back immediately though.

I have noticed that happening after I tried to use 16MHz RC oscillator while keeping 32MHz crystal always off. Then it started to behave like this within minutes, but I also see the same thing with 32MHz crystal, just less often.

I do not change connection settings - intervals and timeouts are whatever mac sends when connection is established.

So is it normal? Has anyone been keeping keyfob connected without link loss for a few days?

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2)

I saw datasheet says 32MHz crystal has to be used in order for rf to work correctly. Are these disconnects one of correctness problems RC oscillator introduces?

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3)

I have quite heavily extended the firmware on top of provided OSAL and HAL code and I noticed that some time consuming tasks I perform can make the keyfob lose the link. Are there some good practices someone can advice and how to know when too much is too much?

  • 0
    Expert 1740 points

     Hi,

    AFAIK, link losses are expected. BLE is, by definition, a technology with unreliable links :)

    Regarding 3), it is quite a challenge. Ran into this myself. I guess the only method is trial-and-error, and then splitting your data processing into series of event-driven subprocedures that return control to higher priority HCI/LL tasks. 

     

  • 0 in reply to Oleg Komlev
    Prodigy 110 points

    Thanks for answer. My top priority is good battery life and splitting logic into small pieces with timers is not good for the battery.

    Anyone can confirm or deny from practical experience if it's possible and worth to run CC2540 on 16MHz RC oscillator keeping 32MHz off?