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Can a BLE connection be disconnected most of the time and reconnected only when it is needed for a sensor network?

Light AiYee
Prodigy 100 points
Other Parts Discussed in Thread: STRIKE

Hi BLE experts,

I have this scenario where multiple BLE sensors will be sending data to a BLE tablet. There is a risk that the tablet may run out of resources if there are too many BLE connections at the same time. One solution is to have the tablet (master) connect to the sensor only when it needs data and after the data is retrieved, the connection is immediately broken. The tablet will do this for all the sensors turn by turn in the neighbourhood. 

May I know if this is feasible with TI BLE chipset?

  • 0
    TI__Guru 56590 points

    Hello Light,

    I think this can work, but have you considered using a broadcast only implementation instead? If you do not need your data to be encrypted you can simply set up your tablet as an observer and receive the broadcast packets from the different sensors.

    If you want to use the disconnect scheme remember that you might end up with a higher average current consumption due to the extra energy used for reconnecting and the advertisement packets the peripheral/slave must transmit for the master to be able to reconnect.

  • 0 in reply to Eirik V
    Mastermind 8695 points

    Its feasible, but the energy required to make that process work quickly will not be low, which is kinda the point of  Bluetooth Low Energy. Discovering and  connecting quickly are inversely proportional to power consumed. Sticknfind has 2/5 stars on Amazon.com because they failed to strike a good balance. They also aren't using a TI chip :D

  • 0 in reply to Eirik V
    Prodigy 100 points

    May I ask where is the higher current consumption going to hit? The Master or Slave or both? It does not matter if power consumption goes up at the Master side.

  • 0 in reply to Light AiYee
    Mastermind 8695 points

    I'm not aware of how to increase power on iOS or Android devices. Listening and receiving both take power. It takes around 15mA to transmit from a CC254X. Connections are dependent on getting a initiating device to be listening while the connectable device is advertising. Two of the factors for discovery time are how many of the 3 advertising channels you advertise on and how often.
    Higher advertisement frequency => shorter connection time and higher power consumption.