SPI bus need to be dedicated to nRF21540?

RE: SPI bus need to be dedicated to nRF21540?

PaKa — Thu, 24 Feb 2022 19:00:24 GMT

Current nRF21540 SW solution does not support SPI control, it relies on GPIO control. For this you will need to have control of PDN, RX_EN and TX_EN. Mode, ANT_SEL, CSN, MOSI and SCK can be tied to power rails while the MISO can be left floating.

There is SPI gain control in the roadmap but timeline is still TBD. This will still require pin control for the PDN, RX_EN and TX_EN (and Mode/ANT_SEL if used).

RE: SPI bus need to be dedicated to nRF21540?

Smart.Enrg — Thu, 24 Feb 2022 17:27:02 GMT

Thanks Priyanka,

What I meant (sorry wasn't very clear) - use of SPI select lines via IO mux, not the 5x FEM interface signals.

So the question is - since I am using IO mux to generate SPI select signals - could you point me to where in
FEM/ SPI driver code I should implement select/ CSN control for FEM please?

Thanks

RE: SPI bus need to be dedicated to nRF21540?

Priyanka — Thu, 24 Feb 2022 12:27:27 GMT

Hi,

You can use the SPI port shared between devices using the CS pins. Also, interfacing the pins directly or via mux is very similar from the application point of view. But FEM can use direct pin control, i.e. it can be controlled via GPIO pins.

Regards,

Priyanka