PA+LNA support on NRF52?

[espruino-discuss]

Posted at 2024-03-21 by @yerpj

I am trying to use Espruino on a NRF21540-DK board (NRF52840+nRF21540 Front End Module, FEM). The latter can be either in TX or RX mode but not both at the same time. It means that the BLE stack should manage the FEM state pins accordingly. Is there anything already built-in to do so?

[espruino-discuss]

Posted at 2024-03-21 by @yerpj

by the way, the idea behind using such an FEM module is to increase range to cover outdoor applications as well. More and more systems and sensors use BLE advertising to publish data and having the possibility to support the FEM would drastically help outdoor applications for environmental sensors or beacon tracking

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Posted at 2024-03-21 by @gfwilliams

I haven't come across this before I'm afraid - but it feels like maybe something that would be handled by the softdevice (as it's going to have to have very fine-grained control).

If it's in the softdevice then modifying Espruino to enable it is probably pretty trivial

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Posted at 2024-03-21 by @yerpj

seems there is already something available, however I am not able to follow it up to the user space
https://github.com/espruino/Espruino/blob/55fbab3847975a40341dd2272d4693b341cc0ffe/targetlibs/nrf5x_12/components/softdevice/s130/headers/ble.h#L109

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Posted at 2024-03-21 by @fanoush

there is more here https://github.com/espruino/Espruino/blob/55fbab3847975a40341dd2272d4693b341cc0ffe/targetlibs/nrf5x_12/components/softdevice/s130/headers/ble.h#L212-L295

so when filled properly it should be configured in similar way to this https://github.com/espruino/Espruino/blob/55fbab3847975a40341dd2272d4693b341cc0ffe/targets/nrf5x/bluetooth.c#L2567C5-L2575C6

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Posted at 2024-03-21 by @yerpj

Thank you both for your quick replies.

So it seems that anyhow, a specific compilation has to be done with edited bluetooth.c file.

I naively thought that this could be solved directly in javascript, but it seems to be more complex.