Hi, 

You can use the RSSI Viewer app. See the Testing with RSSI Viewer doc. 

Regards,
Amanda

hi 

I'm trying to use RSSI Viewer for my custom board - problem is I need to change UART pin.

My custom board uses nRF52840.

tx-pin = <13>;
rx-pin = <14>;

Hi, 

Have a look at this post. 

-Amanda

hi 

I can successfully change my radio_test uart pin.
But I still don't understand how to use the rssi viewer to test my custom board.
When I connect the rssi viewer, he will update the fw of my board first (I think it is the fw of the rssi viewer),

Hi, 

You would need another board (like nRF52840DK) to connect with the RSSI viewer to observe the RSSI of your board.

-Amanda