Help needed with NRF24 reference design

RE: Help needed with NRF24 reference design

ketiljo — Wed, 07 Apr 2021 13:09:02 GMT

The crystal you are using have a CL value of 9 pF. So 15 pF load caps are correct here. The GND pins of the crystal should be grounded, but this shouldn't affect the operation of the crystal

RE: Help needed with NRF24 reference design

makerbob — Fri, 26 Mar 2021 18:06:57 GMT

The crystal is 16mhz and the caps are 22pf. This is the specific crystal I'm using https://lcsc.com/product-detail/SMD-Crystal-Resonators_Yangxing-Tech-X322516MLB4SI_C13738.html

Also, only connecting the crystal pins, gnd are not connected.

RE: Help needed with NRF24 reference design

ketiljo — Thu, 25 Mar 2021 13:11:32 GMT

It can also be the crystal that's out of spec or incorrectly loaded. What is the spec of the crystal you're using? Also the value of the capacitors on the XC1 and XC2 pins?

RE: Help needed with NRF24 reference design

makerbob — Tue, 23 Mar 2021 20:18:12 GMT

OK great. So if I understand correctly, I should add a ground plane on the top layer as well and connect that one with many vias to the bottom ground plane? Apart from that, is there anything else that could hinder the performance of the antenna?

RE: Help needed with NRF24 reference design

ketiljo — Mon, 22 Mar 2021 12:47:24 GMT

You need ground planes on both sides, connected with plenty of vias. The area under the matching network should be solid ground. Route as much as you can on the top layer to make the bottom layer a good ground plane.

The antenna doesn't necessarily needs to look like this. It's just a simple 1/4 wave track. So you can make it a straight track instead. It's more important to keep it away from any metal.