nRF52 GPIO near radio

RE: nRF52 GPIO near radio

Susheel Nuguru — Wed, 18 Nov 2015 08:17:25 GMT

you are right, SPI can only have frequencies where SYSCLK will be harmonics to it. I do not remember any customer complaining about reduced Radio sensitivity, but, because now we are talking about it can't you avoid those pins you mentioned and select different GPIO's.

RE: nRF52 GPIO near radio

jcondon — Tue, 17 Nov 2015 15:02:21 GMT

According to the Product Specification (18.2.1), pins 27-29 and 37-43 are all considered affect the radio with high frequency IO & large sink/source current.

As far as I'm aware, the only available SPI clock frequencies are all harmonics of the system clock because there is only a single clock divider (vs pre/post divisions). Is there another SPI register I'm missing or somewhere else to adjust the peripheral clock speed?

RE: nRF52 GPIO near radio

Susheel Nuguru — Tue, 17 Nov 2015 09:16:06 GMT

Not remember exactly but I think GPIO 18 and 19 are really close the the radio module. And 8MHz clock is harmonics of 16MHz system clock that radio uses and this could cause relatively more noise. If you choose some other pins and/or choose different SPI clock frequency which are not the harmonics of radio clock, then you should not have anything to worry about.