Custom Board not transmitting

RE: Custom Board not transmitting

JONATHAN LL — Tue, 24 Mar 2026 12:36:27 GMT

This is a good result, now we know that there is life in the radio and antenna at least, you are getting a OK amount of power here it seems as well so if the rest is ok then it should work ok.

I suspect that there might be a issue with the crystal load caps. If the crystal accuracy is to far off then its difficult for the devices to talk, it results in a issue where the devices do not operate on the same freq, so that is likely why it does not show up on your phone. You could try with another phone or PC, to see if they are able to connect.

But best way to check is to use a spectrum analyzer, the RSSI viewer app is not good enough to check the accuracy to determine the offset exactly. You would need spectrum analyzer to get the exact value to see how far off it is.

You can try to change the two load caps, go a few pF up or down so see if that improves/solves the situation.

We can also have a look at the prefromance if you are willing to send a unit to us. we will check the radio and antenna and give you a report.

Regards,
Jonathan

RE: Custom Board not transmitting

Raschke — Mon, 23 Mar 2026 23:50:41 GMT

Thanks Jonathon,

The hex file seems to work. I'm now getting a steady peak on channel 17, smaller peak on 18.

- with Custom Board powered

- without Custom Board

RE: Custom Board not transmitting

JONATHAN LL — Mon, 23 Mar 2026 23:18:57 GMT

Hi John,

Can you test with the hex file shared here https://devzone.nordicsemi.com/f/nordic-q-a/120751/device-stops-ble-advertising-after-some-time-in-the-application-code/532146

Also adding it here: devzone.nordicsemi.com/.../2553.nrf52-carrier-ch40-4dBm.hex

This should just start the device in TX.

Regards,
Jonathan

RE: Custom Board not transmitting

Raschke — Mon, 23 Mar 2026 03:13:33 GMT

Hi Jonathon,

I've tried running the Radio_Test on the board. I'm unable to see it with the RSSI viewer app on the nrf52dk.

When I input the commands on the serial terminal, I get the following response from the custom board, and any other inputs receives the same response.

I've set the board rate to 115200 in the dts and tired with different rates but am not getting anything legible.

&uart0 {
	compatible = "nordic,nrf-uarte";
	status = "okay";
	current-speed = <115200>;
	pinctrl-0 = <&uart0_default>;
	pinctrl-1 = <&uart0_sleep>;
	pinctrl-names = "default", "sleep";
};

Best,

John

RE: Custom Board not transmitting

JONATHAN LL — Fri, 20 Mar 2026 11:06:40 GMT

Setup is ok and crystal cap seems ok as well, but for the radio test sample, it will not show up in the app, you will need to use the DK you have connected to you computer running the RSSI viewer app.

You should see a "spike" on the channel you output on on the custom board.

Its to see if there is any life in the radio part of your custom board.

Regards,

Jonathan

RE: Custom Board not transmitting

Raschke — Thu, 19 Mar 2026 23:00:21 GMT

I've tried using the radio_test example. It uploaded but I received the following errors and still cannot see my board on the nrf connect app.

I've also added the following the dts to ensure the dcdc is not used. Will this be ok?

&reg {

regulator-initial-mode = <NRF5X_REG_MODE_LDO>;

};devzone.nordicsemi.com/.../Linking-C-executable-zephyrz.txt

RE: Custom Board not transmitting

Raschke — Thu, 19 Mar 2026 02:43:16 GMT

I've used C0402C120J5HACTU capacitors for C1 and C2, both have 12pF.

Ccap = 2*CL – C_pcb – C_pin

For above, using C_pcb+C_pin = 4pF (From PCB design guide) and CL = 8pF from the data sheet, Gives Ccap = 12pF

RE: Custom Board not transmitting

Raschke — Wed, 18 Mar 2026 23:40:01 GMT

Hi Jonathon,

Thank you for the detailed response. I'll go through these other examples and report back. In the meantime, here is a copy of the crystal data sheet. I'm using the EPSON Q22FA12800025.

devzone.nordicsemi.com/.../C187794.pdf

RE: Custom Board not transmitting

JONATHAN LL — Wed, 18 Mar 2026 07:31:59 GMT

Hi,

So you are able to program the custom board so that is a good first step. It could be good to test with some other non radio applications as well to see that the device behaves normally, but you do not have the DCDC components so be carefull not to flash anything that has DCDC enabled. This will lock up the device and without the correct voltages on some DCC pins it will not boot.

We have a guide on the basics of the design here https://devzone.nordicsemi.com/guides/hardware-design-test-and-measuring/b/nrf5x/posts/general-pcb-design-guidelines-for-nrf52-series there is also one for the nRF52832 with some extra details.

You could use the radio test sample to set the custom board up with single chennal TX unmodulated at max power to make it simple, but you also use a normal sample like the one u have but know that the singal will jump from channels when advertising.

https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/samples/peripheral/radio_test/README.html#testing
https://docs.nordicsemi.com/bundle/nrf-connect-rssi-viewer/page/index.html#rssi-viewer-app

Also if you need any more electrification on something or something is unclear then feel free to ask for more details or anything else.

Something that can be an issue is that the load cap values for the crystal is not correct, offsetting the RF signal so much that the phone can not "see" the custom board.

Do you have the datasheet of the 32MHz crystal ?

Regards,
Jonathan