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BLE notification rate

Michael Ling
Prodigy 170 points
Other Parts Discussed in Thread: CC2640, CC2540

I'm using the SimpleBLEPeripheral and SimpleBLECentral projects (CC2640 chips) to implement notification sending. I'm trying to send 1 notif every 100 ms, but on the Central side, it looks like I'm actually getting a burst of 10 notifs once every second. I feel like either there's a parameter on the Peripheral that queues notifs and sends them once a second, or one on the Central that calls processGATTMsg once a second to handle all built-up messages. Is either guess accurate? Thanks!

  • 0
    TI__Guru 56590 points
    Hello Michael,
    How did you implement the notifications?
    What is your connection interval?
    Are you able to capture a sniffer log?
    Link to sniffer SW: www.ti.com/.../packet-sniffer. You either need a CC2540 Dongle or a separate device running HostTestApp connected to your pc throgh a com port. If not we can try to figure it out anyways :).
  • 0 in reply to Eirik V
    Prodigy 170 points
    Hi Eirik--thanks for the reply. I implemented notifications by writing to the CHAR1 config on connection, then using SimpleProfile_SetParameter to trigger notifs. On the Central side, I added a condition to SimpleBLECentral_processGATTMsg to handle ATT_HANDLE_VALUE_NOTI messages. DEFAULT_DESIRED_MIN_CONN_INTERVAL is 80 and MAX_CONN_INTERVAL is 800 (so 100-1000 ms).
    I don't have a dongle, unfortunately; I set a LED to blink on receiving a notif and measured the output pin with an oscilloscope, which is how I saw the "burst" notification.
  • 0 in reply to Michael Ling
    TI__Mastermind 33460 points
    Hi Michael,

    It is important to make sure that both devices are using a 100ms connection interval. Can you try to set the MAX_CONN_INTERVAL parameter to 800 as well?
  • 0 in reply to Sean2
    Prodigy 170 points
    Hi Sean, do you mean to set MAX_CONN_INTERVAL to 80? The current value is 800.
    On the Central board, MIN_CONN_INTERVAL is 400 and MAX is 800--since DEFAULT_ENABLE_UPDATE_REQUEST is false, does that matter?
  • 0 in reply to Michael Ling
    TI__Mastermind 33460 points

    Yes I mean 80. You should set min and max values on both central and peripheral to be 80 so that a 100ms connection interval. Otherwise they may agree on a higher interval which would likely cause the burst you are seeing because data can only be sent at connection events.