nRF52840 beacon transmission are skipped in long range mode.

[Abhishek]

Hii,

I am using nRF52840 module in beacon mode which is transmission one value read from sensor. According to code sensor sampling and transmission cycle is controlled by app timer. Timer is set to 5 seconds. This application is working properly in BLE_GAP_ADV_TYPE_NONCONNECTABLE_NONSCANNABLE_UNDIRECTED transmission mode.

When transmission mode is changed to BLE_GAP_ADV_TYPE_EXTENDED_NONCONNECTABLE_NONSCANNABLE_UNDIRECTED app timer and sensor sampling is working properly according to timer, but when monitored on nRFConnect app on android device packet reception is observed on interval of 20 seconds.

I am unable to understand if this is issue with code or issue with app. (mobile supports BLE 5 PHY codded communication)

Please help me resolve this issue.

Best regards.

[Simonr]

Hi

What phone are you using for scanning? We recently had this issue with a number of other phones as well. How have you confirmed that your phone supports BLE 5 Coded PHY? If you did so using the nRFConnect app device information, I'm afraid that can't be trusted, as we're currently just displaying what the Android API is returning, something that not necessarily means full Coded PHY support. 

This is because a lot of phones does support scanning on the secondary channels used in extended advertising, which is why you can only see the advertising every ~20 seconds. So you're not able to scan and connect to devices advertising using Coded PHY I'm afraid. What you can do though, is to scan and connect using one of the uncoded PHYs, either 1MBPS or 2MBPS, and update the PHY to Coded once connected, that way you should be able to communicate long-range either way.

The only phone I've personally tested long-range scanning/connecting with successfully is the Samsung S10E. While with a Samsung Galaxy A70 and a Nokia 8.1 we've confirmed the same behavior you're seeing.

Best regards,

Simon