Android delayed notification

[gaminn]

Hi, on Android, I sometimes get delayed notifications. I measure realtime data and send them over notification, and I can see data change on Android with approx 1 s delay. Sometimes it helps to connect and disconnect BLE device.

On Windows notifications always work.

I send 20 notifications/second with approx 20 ms connections interval.

[Hung Bui]

Hi,

We need to check if the connection interval is actually 20ms or not because the central/peripheral can request to change it.

1s delay is for all notification packets (each packet comes after 1 second) or only the first offset delay, after that notification comes every 20ms ?

You may need to capture a sniffer trace to really see if the notification is sent with 20ms interval or not.

I would suggest to use nRFConnect app on Android to test.

[gaminn]

I set 200 ms connection interval. Then on any central connected to my periphreal I can see the data update is not as smooth as with 20 ms interval. But there is no 1s lag (every notification packet arriving with 1 s delay). So the issue is probably not related to the connection interval. I can remember that I saw this 1s notification lag also in nRFConnect app with my devices, always on Android. I have never seen this issue on Windows.

[gaminn]

I use nrf51/nrf52 S110/S132 (I experienced this issue with both devices). Does S110 or S132 buffer notifications before it sends them?

[Hung Bui]

Please try to capture a sniffer trace.

Please try to test with ble_app_hrs, try to change HEART_RATE_MEAS_INTERVAL to APP_TIMER_TICKS(100) and MIN_CONN_INTERVAL and MAX_CONN_INTERVAL to MSEC_TO_UNITS(100, UNIT_1_25_MS) .