No pins for connect nRF21540 to nRF5340

[SBou]

Hi, in our project with the nRF5340 we desire use the nRF21540 to have a long conection for BLE, the problem is we don't have any pin free in the nRF5340 to manage the nRF21540 and we at this moment don't wish manage the nRF21540 from the nRF5340, only wish use as amplifier.

Because this we think control the pins on nRF21540 with pull-up and pull-down resistor, our doubts are:

Does any problem if we use resistors to manage the estates otf the pins on the nRF21540?

With the configuration in our schematic with pull-up and pull-down resistor Is it in the on state and is good configurated?

Thanks in advance.

[Bendik Heiskel]

Hi,

It's only possible to set the nRF21540 to one single state by tying the GPIO pins high/low in hardware. This will not work if you application only TX or RX.
The power consumption will also be high if the PDN pin is tied high constantly.

The minimal number of GPIO pins needed to connect to the nRF5340 is 3, PDN, RX_EN and TX_en. If doing this the other pins should be tied to GND, except for CSN which should be connected to PDN.

This will always give you 20dB TX gain, and only ANT1 can be used. ANT2 must be tied to ground with a 49.9 or 50Ohm.

 

Best regards,

Bendik