What crystals should I use, what's RFIO

Thread Starter


Joined Apr 21, 2022
Hello everyone, I'm new to pcb designing and I'm having trouble choosing the right crystals for atmega328pb-au and nrf24l01p-r. I looked into many different example schematics and decided to use these crystals in these arrangments (photos attached), I'd like to ask if I'm using the correct crystals and in correct arrangements? (HCM4916000000ABJT for nrf24l01 and CSTNE16M0V530000R0 for atmega328pb)
Also in the last photo I've included an example of nrf24l01 schematics and it says 50ohm RFIO. I assume this is where the antenna goes and I'd like to ask if I'm supposed to use a 50ohm resistor or an antenna of 50ohm or what does 50ohm RFIO mean?
Any help is appreciated.



Joined Jan 27, 2019
50Ω refers to the impedance of the antenna, and also of the PCB tracks that make up the connection to it. Layout for RF output is very critical. Your best bet is to study the reference design Nordic provides for the nRF24L01 or the evaluation board layout.