Custom nRF52832 board doesn't radiate

RE: Custom nRF52832 board doesn't radiate

Hossein Kasaei — Wed, 08 Feb 2023 18:58:44 GMT

Thank you so much, replacing crystal with a better one solved the problem ! 🙂

RE: Custom nRF52832 board doesn't radiate

Kaja — Wed, 08 Feb 2023 11:09:59 GMT

I'm concerned that you have chosen a crystal out of spec, and that the radio won't start because the clock/crystal does not start.

Specificaitons: https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/clock.html?cp=5_2_0_18_3_1#unique_1670581351

The crystal from our DK: Q22FA12800025, from Epson Toyocom.

A four pad crystal, with ground pads in addition to crystal pads.

Best regards,
Kaja

RE: Custom nRF52832 board doesn't radiate

Hossein Kasaei — Wed, 08 Feb 2023 08:21:34 GMT

Hi,

Unfortunately the manufacturer doesn't provide the datasheet for the specific 32MHz crystal. Here is their link.
It seems that you are suspected to the crystal. Is it something related to the PPM? I think I've chosen a bad crystal for my board. Can you tell part number of good crystals suited for RF applications?

RE: Custom nRF52832 board doesn't radiate

Kaja — Wed, 08 Feb 2023 08:03:12 GMT

Hi,

I need the datasheet for the specific 32 MHz you have mounted, not the series of crystals the vendor offers.

Best regards,
Kaja

RE: Custom nRF52832 board doesn't radiate

Hossein Kasaei — Tue, 07 Feb 2023 14:02:58 GMT

Hi,

Thanks for your tips I'll consider them for next designs.

datasheets :

devzone.nordicsemi.com/.../nsk_5F00_crystal.pdf
devzone.nordicsemi.com/.../CM415-datasheet.pdf

RE: Custom nRF52832 board doesn't radiate

Hossein Kasaei — Tue, 07 Feb 2023 13:32:14 GMT

I changed the capacitor but the problem is still there.

RE: Custom nRF52832 board doesn't radiate

Kaja — Tue, 07 Feb 2023 13:23:49 GMT

Hi,

here you have done a couple of design mistakes on the RF part of the design:
1. There should not be any routing under the RF path.
2. The grounding of C13 should be done via the VSS pin 31.
3. There should not be any routing under the 32 MHz crystal.

There are more things to improve, but first:

Can you upload the datasheet for the two crystals you are using? Both for the 32 kHz and the 32 MHz.

Best regards,
Kaja

RE: Custom nRF52832 board doesn't radiate

Hossein Kasaei — Tue, 07 Feb 2023 13:01:48 GMT

Hi,

C13 has 0805 footprint which is not the most suitable option for the RF front end, but it is selected based on available components. 0.8pF capacitor with 0805 package is not wired, but your answer suspect me about the value of capacitor I bought, so I checked it with capacitance meter and found out that it is 4.7uF cap which is the supplier mistake. I'm going to change the capacitor and will announce about the result.

RE: Custom nRF52832 board doesn't radiate

Frank Viganske — Tue, 07 Feb 2023 12:31:11 GMT

Hi,

the C13 footprint looks quite large for a 0.8pF capacitor. Are you sure you have used the right value here? I'd expect C13 to be have the same footprint size as C14.

Best regards

Frank