Hey everyone,
I got a question regarding the BLE Advertisement with the nRF52840 (Softdevice s140). I am using the nRF Connect SDK with Zephyr and currently working on a BLE Mesh project.
I am a bit confused regarding the documentation of the Softdevice specifications, the Bluetooth Low Energy specifications and the Online Power Profiler.
According to the Bluetooth SIG a random delay between 0-10ms shall be added before every advertisement. However, in the Softdevice specifications it is mentioned, that the Softdevice will add a random delay between 3-13ms. If I configure an advertisement interval of 20ms in my software wouldn't that mean, that the theoretical smallest advertisement interval is 23ms?
Furthermore, if I select a 20ms Advertisement Interval in the Online Power Profiler for the nRF52840, a 25ms Interval will be shown in the "BLE event details". I am trying to model the packet transmission delays, hence it would be nice if someone could help me to clarify what the actual advertisement interval will be when I am using the nRF52840.
Furthermore, I got a question regarding additional delays. If the Bluetooth device is in the RX state and it wants to transmit an advertisement packet it will of course switch to the TX state, but will there be any additional delay except the radio switch delay? If an advertisement packet is included in the advertisement queue and is to be sent next, then a random delay is applied before the packet is sent. Afterward, the advertisement interval is started by sending the packet as fast as possible, but are there any other delays worth mentioning between advertisement delay and advertisement interval like pre-processing and post-processing which are not included in the advertisement interval?
Regards,
Bjoern
