BLE Eddystone example: unable to change TLM TX Power

[NordicHam]

Good day,

I program my nRF52-DK with BLE Eddystone example's pre-compiled hex:

\nRF5_SDK_15.3.0_59ac345\examples\ble_peripheral\ble_app_eddystone\hex\ble_app_eddystone_pca10040_s132.hex

Slot 0 transmits URL frame by default at 0dBm.  I then use nRF Beacon for Eddystone Android app to change Slot 0 to TLM and disconnect - all good.

But when I try to adjust the TLM frame's TX power to e.g. -20dBm, or even -4dBm, I get Error 133 in the Android app.

With Slot 0 = URL I can change TX power to -20dBm.

Please check if you get the same results using the Android Eddystone app?  I am using the Android app on Huawei Mediapad T1 with Android 4.3.  I am unable to connect using my Moto G5 with Android 8.1 as per my other ticket.

Thank you

[ovrebekk]

Hi

I reproduced the problem, and traced it down to an app_error_check on line 154 of es_slot.c in the Eddystone source code. 

Essentially the nRF52 will assert if you try to change the TX power on a TLM slot, it will only work on UID, URL and EID slots.  

One of the designers believe this is enforced by the Eddystone specification, and that you are not supposed to set TX power directly on TLM packets. 

As mentioned here "TLM should be interleaved with an identifying frame such as Eddystone-UID or Eddystone-EID", and you can set the TX power on the interleaved UID or EID packet (slot) instead. 

So for now please refrain from trying to set the TX power on a TLM slot. I will discuss this with the app developer and see if we should change the app to remove this configuration field for TLM slots. 

Best regards
Torbjørn

[NordicHam]

Noted, thank you Torbjørn.

Regards
Jacques