nRF21540 FEM SPI TP Out for MFG line programming

[spandian]

Hi Nordic Team,

I see that I am supposed to GND 2 of the SPI lines and drive the CSN high to use it in GPIO control only mode. We wanted to TP out the SPI bus for the FEM in order to program the two gain modes on the MFG line to be different from the default 10 and 20 dB stages. What is the best solution for this?

Thanks,

Sundar Pandian

[PaKa]

You are not required to ground the lines even if you don't plan to use the SPI unit, the reason pins are listed as tied to VDD/GND is that if the module is not used the pins can't be left floating and tying them to a power rail is the easiest way to fix this. Just make sure to keep CSN line high when not using the SPI interface.

Programming the gain at production time should only require you to keep CSN line high when application is in use.

Note the operation voltage requirement for programming the OTP in the nRF21540: 3.45V-3.60V