Can connect to cellular with evaluation board but not with custom board (with the same sim)

RE: Can connect to cellular with evaluation board but not with custom board (with the same sim)

Charlie — Tue, 13 Aug 2024 13:34:39 GMT

Antenna tuning is different with RF circuit design. You can learn about antenna tuning here https://youtu.be/x1m8G8MAeUQ?si=fSr_QNilFlcWliKv.

When you generate a new private ticket to request antenna tuning. My colleague working on HW will request some HW samples of your product and check your antenna design and RF components, then give you advice.

For the test command, you can refer to Production test commands (nordicsemi.com) to decode the test commands.

Best regards,

Charlie

RE: Can connect to cellular with evaluation board but not with custom board (with the same sim)

Byter — Tue, 13 Aug 2024 10:48:04 GMT

Hi Charlie,

Thank you. What files do you need us to provide?

On another note, we tried the XRFTEST commands and are curious what do these results mean:

AT+CMEE=1
OK
> AT%XRFTEST=0,1,3,8000,-75,0
+CME ERROR: 0
> AT%XRFTEST=1,1,5,8300,18,0,3,12,0
%XRFTEST: 0
OK

We copied the exact values from the examples of pages 14 and 15 in the nrf9160 hardware integration guide

RE: Can connect to cellular with evaluation board but not with custom board (with the same sim)

Charlie — Tue, 13 Aug 2024 09:06:26 GMT

Hi Avishay,

Feel free to generate a new private ticket and request free antenna tuning service from us.

Best regards,

Charlie

RE: Can connect to cellular with evaluation board but not with custom board (with the same sim)

Byter — Mon, 12 Aug 2024 08:17:32 GMT

Hi Charlie,

Our board was checked by the antenna manufacturer.

They provided component location instructions, component routing instructions and impedance.

It's possible that the manufacturer's recommendations were incorrect.

RE: Can connect to cellular with evaluation board but not with custom board (with the same sim)

Charlie — Thu, 08 Aug 2024 10:39:26 GMT

Hi Avishay,

Do you mean you have requested antenna tuning for your current PCB board?

Did you get any advice about the match network components value, or it is just OK without needs for adjustment?

You could do side by side comparison with an nRF9160DK to further confirm the suspicion about the weak signal.

Best regards,

Charlie

RE: Can connect to cellular with evaluation board but not with custom board (with the same sim)

Byter — Thu, 08 Aug 2024 08:47:35 GMT

Hi Charlie,

After further investigation, we looked again for the impedance on the PCB design Gerber files.

We've been doing the impedance until the first element on the antenna matching circuit. Under the antenna matching elements until the antenna component we didn't do any impedance layer.

Is this the correct design?

Additionally, we can send you the Gerber or drd files.

RE: Can connect to cellular with evaluation board but not with custom board (with the same sim)

Byter — Thu, 08 Aug 2024 07:20:41 GMT

Hi Charlie,

I've checked with our hardware engineer here's what he said:
1. We did a hardware review with you - on a different account because this is my personal one

2. We sent the design to the antenna manufacturer and they approved it as well

Unfortunately we don't have an external antenna connector so we can't test it out. What do you suggest we should do now?

RE: Can connect to cellular with evaluation board but not with custom board (with the same sim)

Charlie — Tue, 30 Jul 2024 09:17:30 GMT

Hi Avishay,

This is Charlie, and I am looking at this ticket due to Øyvind is not available.

The previous CESQ responses with rsrp value 10 and 37, which corresponding to -130dBm and -103dBm signal strength. These two values reflect poor signal strength. Which make the device stay at the following connection states.

2 – Not registered, but UE is currently trying to attach or searching an operator to register to

4 – Unknown (for example, out of Evolved Terrestrial Radio Access Network (E-UTRAN) coverage)

Can you confirm if you or your colleague have request hardware review or antenna tuning? I do not see you have other hardware related ticket.

If you have reserved external antenna connector on your custom board, you can also try to test with external antenna to see if it will make any difference.

Best regards,

Charlie

RE: Can connect to cellular with evaluation board but not with custom board (with the same sim)

Byter — Sun, 21 Jul 2024 06:19:05 GMT

devzone.nordicsemi.com/.../trace_2D00_2024_2D00_07_2D00_21T06_2D00_12_2D00_40.364Z.mtrace

Here's the file of a separate trace as I didn't save the last one. All I did was AT+CFUN=1 and let it run

RE: Can connect to cellular with evaluation board but not with custom board (with the same sim)

Øyvind — Wed, 17 Jul 2024 13:13:28 GMT

Please provide the trace file (.mtrace) in this ticket as there is not enough information in the screenshot.

RE: Can connect to cellular with evaluation board but not with custom board (with the same sim)

Byter — Tue, 16 Jul 2024 06:46:43 GMT

I will try to add another uart-to-usb connection in order to have the modem tracing available. This will be later on today and I will update the ticket with what I've found. It did work without issues on the DK. Also I tried with another SIM card beforehand and got the same issue; it tries to connect but never succeeds.

At one point I thought it might be a certificate issue. I've found about nrf cloud and onboarded the device successfully. But it didn't change anything. Although the output of the certificates did appear weird for me:

0            DEV_ID_PUB_KEY     0606060606060606060606060606060606060606060606060606060606060606
16842753     ROOT_CA_CERT       2C43952EE9E000FF2ACC4E2ED0897C0A72AD5FA72C3D934E81741CBD54F05BD1
16842753     CLIENT_CERT        ACD06EB3963CAAD4D2B4C8A533AAC8670C232D62A085FE14EF31A23546845BFC
16842753     CLIENT_KEY         29D6686F6BF862C96218DFDB2F3C36D67B6E54B9F1EDDB2CF3507C37CE179456
4294967293   NORDIC_ID_ROOT_CA  2C43952EE9E000FF2ACC4E2ED0897C0A72AD5FA72C3D934E81741CBD54F05BD1
4294967294   DEV_ID_PUB_KEY     FF66BD94DF70DFED1FADA1796C744D02CA02F8491BA45D68B8F97D25B7F7AA15
4294967292   NORDIC_PUB_KEY     2027C4699EAA90A414D33FA81B975C0FDEDEFB04A19CEA1ED43A8876CAD31E89

As you can see there is a DEV_ID_PUB_KEY and its sha seems oddly fake. I don't know what that means or if it's related to my issue but decided to share this information just in case. The DK doesn't have any certificate on tag 0

EDIT: I've added the tracing results to the main post, let me know if you want something more specific from the tracing

RE: Can connect to cellular with evaluation board but not with custom board (with the same sim)

Øyvind — Tue, 16 Jul 2024 06:18:34 GMT

Hello,

are you able to provide a modem trace from the device when the issue occurs? Did this work without issues running on the nRF9160DK? Have you tested other SIM cards than Pelephone?

Kind regards,
Øyvind