RE: How to Use nRF21540 FEM on BL5340PA DVK

ovrebekk — Tue, 23 May 2023 07:56:53 GMT

Hi Tyler

Please do.

Ideally it should be enough to use their board files and set a high output power (+10 for instance), and everything else would be handled for you, but it requires the nRF21540 to be properly enabled in the board files.

Best regards
Torbjørn

RE: How to Use nRF21540 FEM on BL5340PA DVK

Tyler_H — Mon, 22 May 2023 12:27:23 GMT

Hi Torbjørn,

Thank you for your help and the information! I will reach out to Laird for additional information as well.

RE: How to Use nRF21540 FEM on BL5340PA DVK

ovrebekk — Mon, 22 May 2023 11:26:53 GMT

In general you would need to ask Laird for input if you are using their hardware and software, but I will provide some general comments.

How to work with FEM devices (not specific to the nRF5340) is described here.

One thing you need to do in order to make the FEM work on the nRF5340 is to add some configuration to the hci_rpmsg.conf file in the child_image folder of the project. The Broadcaster sample you mention doesn't include this file, but you can look at other samples to see how this is done. As an example the peripheral_hr_coded sample includes this file (with configuration settings needed for long range).

My colleague Hieu provides the configuration parameters needed for the FEM to work on the nRF5340, here.

Looking at Laird's own documentation in the manifest you linked to it seems the BL5340PA does not use the SPI interface to communicate with the nRF21540, only the TXEN, RXEN and PDN pins. This means you will have limited control over the output power since you can only set the TX power of the nRF5340 radio, and not change the gain of the nRF21540.

Best regards
Torbjørn