How to verify that the 32MHZ crystal is actually working (nRF52832?

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

JONATHAN LL — Sun, 04 May 2025 21:53:28 GMT

Happy to help, glad we could solve the issue. We are here to help so no problem asking questions, will always do our best to solve the issue 😊

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

abdosalm — Sun, 04 May 2025 02:29:15 GMT

After I got home, I tried it and it could be detected and bonded with the nRF Connect App.

didn't know that changing the crystal caps from 8pF to 18pF would have that effect.

Thanks a lot, JONATHAN LL (JonathanLL), and sorry for any disturbance I may have caused.

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

abdosalm — Sat, 03 May 2025 05:57:10 GMT

I have removed the 0.8pF capacitor on the ANT pin side so that I only examine the output of the antenna without any other passive components. I changed the load capacitors of the crystal from 7pF to 18pF, and I noticed the frequency shift has reduced to ~11 KHz. I don't know if this is still acceptable or not.

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

JONATHAN LL — Tue, 29 Apr 2025 07:58:01 GMT

The crystal that you link to is ok to use. No issues there so it should be fine. But sometimes there are issues with single units so that might be what is going on, do you have a spare that you can try and replace.

[quote user="abdosalm"]I am using with a 7 pF load capacitor:[/quote]

The links say 12pF on the CL, so this should give you a 12pF*2 - 4pF = 20pF, formula can be found here: https://devzone.nordicsemi.com/guides/hardware-design-test-and-measuring/b/nrf5x/posts/general-pcb-design-guidelines-for-nrf52-series

So try to change to 20pF first then see if that helps.

Regards,
Jonathan

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

abdosalm — Mon, 28 Apr 2025 13:18:03 GMT

ok, I will try with new crystal load caps, but as mentioned in the post, this is the crystal I am using with a 7 pF load capacitor:

https://www.lcsc.com/product-detail/Crystals_YXC-Crystal-Oscillators-X322532MOB4SI_C9009.html

I will try to change its capacitance values, but is it or is it not out of spec?

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

JONATHAN LL — Mon, 28 Apr 2025 13:10:23 GMT

Thanks for all the info.

So the crystal you have does do its thing but it does it badly. It is 350kHz off the wanted frequency here so that is why you have issues. Its way outside the spec.

You can try and load the crystal with some other caps to see if you can get it closer but not sure you will be able to get it all the way.

If you have 12pF caps no try to use 22pF and check the center freq again.

Might need a new crystal.

Regards,
Jonathan

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

abdosalm — Sun, 27 Apr 2025 09:10:06 GMT

I have done the test and noticed the following:

At central frequency = 2.44 GHZ and the span = 100KHZ -:

At central frequency = 2.44 GHZ and the span = 1MHZ -:

At central frequency = 2.4403 GHZ and the span = 100KHZ -:

Note that I didn't remove a 0.8pF capacitor on the ANT pin Side, meaning that the ANT pin is connected directly to the spectrum analyzer, and the 0.8pF capacitor is connected between the ANT pin and the ground.

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

JONATHAN LL — Wed, 23 Apr 2025 08:18:20 GMT

Looks like the radio is working at least, so that seems to be in order.

It might be that the 32MHz clock is a bit off. Can you sett the Resolution bandwidth to 1kHz and View bandwidth to 1kHz. Then we can see how accurate the carrier signal is.

Ideally you should have something that looks like this:

So if the carrier offset is bad then things like this can happen.

Regards,
Jonathan

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

abdosalm — Sat, 19 Apr 2025 22:49:53 GMT

I have made the tests that were discussed before, I downloaded the .hex file you provided to me before and here are the results:

This is the output of the ANT pin on the spectrum analyzer without being connected to the Antenna or the matching network:

As you can see, there is a peak at 2.44 GHZ. I then used the nRF52840 USB dongle as an RSSI viewer, and here are the results:

Before powering the MCU:

After powering the MCU, where both of the boards are placed closely together:

There is a clear peak at 2.4 GHZ.

Nevertheless, when I programmed the MCU with the Bluetooth sample example,, the mobile app doesn't detect the presence of any Bluetooth devices:

I have this mobile app with another MCU vendor for Bluetooth connectivity (BLE 5.3), and it worked successfully, so I don't think it's the mobile app but rather the code. I can't seem to know what's wrong with the code. I am using the 32 KHZ crystal oscillator that's required by the example code. All of the functions being called in the code doesn't return any errors.

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

Turbo J — Thu, 03 Apr 2025 06:37:59 GMT

Broken antenna or connector only reduces the range to less than about 1m.

If you have sender and receiver close together you should still be able to get a connection working, BTDT.

It just won't work across the room, and can be very directional.

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

JONATHAN LL — Wed, 02 Apr 2025 14:01:10 GMT

[quote user="abdosalm"] I have access to a SA and VNA but using those will have to wait until UFL connectors arrive.[/quote]

This is the best to use, you could connect a normal 2.4GHz antenna to the Spectrum Analyzer and see as well. Or wait for the connector.

We often end up soldering directly on to the RF path with a coax cable and connect that to the Spectrum Analyzer to check how well the radio preforms. If you have something similar then that will do as well.

Regards,
Jonathan

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

abdosalm — Wed, 02 Apr 2025 13:16:41 GMT

I am afraid I don't have anything that can measure Bluetooth RSSI currently, I have access to a SA and VNA but using those will have to wait until UFL connectors arrive. Currently, I am waiting for the nRF52840 USB Dongle to arrive and I will keep you posted regarding my problem once I receive that dongle.

Thanks a lot and sorry for any disturbance I may have caused.

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

JONATHAN LL — Wed, 02 Apr 2025 13:10:38 GMT

You would need a DK or a dongle, but if you have something else that can measure Bluetooth RSSI then that might also work. But the nRF52840 USB Dongle will also do the trick.

Regards,
Jonathan

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

abdosalm — Wed, 02 Apr 2025 12:51:19 GMT

That's my small problem: I don't have an nrf52DK. I have multiple of my custom boards. That's why I ordered the nRF52840 Module USB Dongle. So can I use 2 of my custom boards to do that test? or shall I have the nRF52840 Module USB Dongle to do the test?

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

JONATHAN LL — Wed, 02 Apr 2025 12:47:44 GMT

We are only interested in seeing if the device works to some extent, even with a poorly tuned antenna you might still see something and could still get some range. But that we dont know, so the antenna might work fine.

Also with the hex file i shared we are not looking to sniff packets, we only look at the transmitted signal, there is no data there. Only a continues wave.

If you have a nrf52DK and your custom board then that is enough to do the test.

Regards,
Jonathan

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

abdosalm — Wed, 02 Apr 2025 12:06:57 GMT

Got it.

But there still exists a small problem, should be the unit that's it to be connected to the RSSI app to have a tuned antenna which I don't have. That's why I have ordered the nRF52840 Module USB Dongle like in the image:

to use it as a packet sniffer, or don't I have to?

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

JONATHAN LL — Wed, 02 Apr 2025 05:42:26 GMT

[quote user="abdosalm"]Unfortunately, I have damaged all of my UFL male PCB connectors[/quote]

As long as the antenna works you should be able to get some results, as you see from the images i shared there is no need to use the UFL connector here, so no ned to connect the two units.

Regards,
Jonathan

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

abdosalm — Tue, 01 Apr 2025 22:25:28 GMT

Sorry for the late reply,

When you first replied above with the '.hex' file to be flashed onto the target. When I tried to do it via black magic debugger, the debugger gave me an error but I tried to do it again today with segger jlink and it was downloaded successfully.

Unfortunately, I have damaged all of my UFL male PCB connectors and I have ordered some that are expected to arrive in 20 days, until then, I can think of nothing to do to debug my problem. once the connectors arrive, I will keep you updated on my problem.

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

JONATHAN LL — Mon, 31 Mar 2025 08:06:54 GMT

[quote user="abdosalm"]Sorry for the late reply but I used a spectrum analyzer to make sure there was a signal being transmitted and I actually could see some peaks temporarily in the 2.4 to 2.5 GHZ bandwidth.[/quote]

This is not good enough, there are channels and specific frequencies so if there is an offset it might cause poor BLE performance ans it might just be bordering on acceptable results.

This might also be the reason why device only works with\shows up on some devices and not others as sometimes there is a similar offset on some devices that work in favor for them.

Also its not just the antenna, its the whole RF performance we want to look at, so the clock and the emission, so maybe you could share what you saw on he spectrum analyzer? Using the hex file i provided, as it will give a clear result that is easy to evaluate.

Regards,
Jonathan

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

abdosalm — Sat, 29 Mar 2025 09:52:14 GMT

The application already has all the permissions it needs:

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

Turbo J — Sat, 29 Mar 2025 08:18:19 GMT

Check permissions.

If you can't scan BTLE stuff in nrf connect for mobile app on android, you don't have "coarse location" permission enabled.

Note that you can't see connected devices as they usually don't advertize at all.

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

abdosalm — Fri, 28 Mar 2025 20:46:45 GMT

Hi Mr.Jonathan.

Sorry for the late reply but I used a spectrum analyzer to make sure there was a signal being transmitted and I actually could see some peaks temporarily in the 2.4 to 2.5 GHZ bandwidth.

However, the nRF52 BLE can be seen on my laptop but not via nRF connect app on my android mobile phone:

when I tried to connect to it via my laptop, it gave me an error and I can see from the logs on the nRF52 side these logs:

so the antenna is working but is there anything to be modified from the nRF Connect App side for such an error?

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

JONATHAN LL — Mon, 03 Mar 2025 14:29:54 GMT

Hi there,

You can use the radio test sample to check if the radio works, you can select const carrier and sett 0 og +4dBm as output and then you should see something with an RSSI viewer.

Or you can use this HEX, it just puts the device on constant carrier on channel 40 (2440MHz).
devzone.nordicsemi.com/.../8267.nrf52-carrier-ch40-4dBm.hex

Open you can use the nRF52 DK as a RSSI viewer,

This is what it would look like if you have just normal (office) background noise.

And this is what it would look like if the radio is sending a constant carrier on the selected channel.

It does not show if the 32MHz crystal is correctly loaded as the PPM is not really measurable this way, but it does show if there is something going on at least.

See: https://devzone.nordicsemi.com/guides/hardware-design-test-and-measuring/b/nrf5x/posts/general-pcb-design-guidelines-for-nrf52-series

Also we do HW reviews here so for future projects feel free to ask for a second pair of eyes to have a look at the design.

Regards,
Jonathan

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

abdosalm — Mon, 03 Mar 2025 12:14:33 GMT

I am using the nRF Connect app. All permissions are granted for the app. Nevertheless, I will try to scan using the PC. I tried using my android Bluetooth scanning but nothing appeared.

RE: How to verify that the 32MHZ crystal is actually working (nRF52832?

Turbo J — Mon, 03 Mar 2025 12:01:19 GMT

The mobile app may not work or may not have all the privileges it needs to work.

The scanner tab is almost never empty for me with all the filters disabled. So if you see nothing at all, its very likely not scanning... Check the app privileges in settings.

You can also check with the "add device" dialog in a PC/Mac OS. Win11 has changed the bt dialog a bit, you will need the additional click on "Show all devices".