Notify arrives late (timing problem)

[Chris G.]

Hey guys. We are using the NRF52 with SDK 13.0.0.1-alpha. If we connect the NRF52 to our own android or iOS APP we have some timing problems with notifications. When the smartphone is connected to the NRF, the user writes from smartphone into a characteristic(rx) and gets an ACK in another characteristic(tx) over notify. The problem is that the notification arrives only after 300ms and we dont know why.

Following things we already have tested: (1) If we send for example 100 notifications in a row we get them very fast(about 30 notifications a second) (2) Disable other bluetooth devices, so that we dont have traffic from other advertisements. (3) We traced the time(start: on_write(rx) event until send notification on tx) and we only need 0,20 ms. I hope you can give me some information :)

[FormerMember]

Do you see the same problem if you use nRF Connect (iOS)?

How do you enable the notifications?

[FormerMember]

Could you use the LOG module to log when the notification is put in the TX buffer, when sd_ble_gatts_hvx() is called? And also log when the notification has been transmitted (BLE_GATTS_EVT_HVN_TX_COMPLETE)?