Custom PCB nRF9160 Link monitor ports

[Yano]

Hi, We have a custom design using an nRF9160.

We can connect and program the device using a jLink though the debug port.

How can we connect the LTE link monitor to the board to transfer AT commands?

Currently our PCB only has access to P0.18 and P0.19 for debug (this can be modified in the next PCB revision).

Can these be re-programmed or are they part of the soft device?

Thanks

[Yano]

Hi Håkon,

I was just thinking the same!

Before I read your post I had just checked it.

I had modified our USB interface to work with 1.8V and of course our hardware is working at 3.3V

So it worked fine with the DK but not our hardware.

So I am getting a response!!

A few more questions:

1. Is there a way to start the AT client in code, so the test house don't have to use a terminal to start it?

2. I need to see if it is working (e.g. getting responses back from cells) is there an AT command I can use?

3. Do I need the overlay in the SPM (secure boot) project?

Sorry for hassling you I'm under a lot of pressure to get this into test tomorrow.

Thanks

Ian

[Håkon Alseth]

Hi Ian,

 

Yano said:

Sorry for hassling you I'm under a lot of pressure to get this into test tomorrow.

Don't worry about this. That is no problem at all, and I'm very happy to help you out.

 

Yano said:

I had modified our USB interface to work with 1.8V and of course our hardware is working at 3.3V

So it worked fine with the DK but not our hardware.

So I am getting a response!!

This is great to hear! Just to confirm: You can now communicate in LTE Link Monitor with your own hardware, and the FTDI USB/UART bridge?

 

 

Yano said:

1. Is there a way to start the AT client in code, so the test house don't have to use a terminal to start it?

 It is possible to hard code certain AT commands, but you usually do not want to do this, as you want to keep the firmware as versatile as possible, in case the test house needs to do certain RF testing on other bands etc.

The easiest thing is to use the at_client, and manually call the AT commands, for instance AT%XRFTEST for RF PHY evaluation:

https://infocenter.nordicsemi.com/topic/ref_at_commands/REF/at_commands/production_test/xrftest_set.html?cp=2_1_10_1_0

 

Yano said:

2. I need to see if it is working (e.g. getting responses back from cells) is there an AT command I can use?

From the LTE Network? AT+CEREG can give you the network registration status: https://infocenter.nordicsemi.com/topic/ref_at_commands/REF/at_commands/nw_service/cereg.html?cp=2_1_7_9

 

Yano said:

3. Do I need the overlay in the SPM (secure boot) project?

 This is not directly needed. By adjusting your at_client/CMakeLists.txt file and adding this:

if (EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/${BOARD}.overlay")
  set(mcuboot_DTC_OVERLAY_FILE "${CMAKE_CURRENT_SOURCE_DIR}/${BOARD}.overlay")
  set(spm_DTC_OVERLAY_FILE "${CMAKE_CURRENT_SOURCE_DIR}/${BOARD}.overlay")
endif()

 

Then you are telling the multi-build system to also include your $(BOARD).overlay file to be applied for spm and potentially mcuboot (if present).

This is the equivalent operation to manually going into the spm project and pasting your $(BOARD-NOT_NS).overlay file into that directory.

 

As your at_client is setup at this moment, it successfully setup the uart pins to P0.18/P0.19.

 

Kind regards,

Håkon

[Yano]

Hi Hakon,

It's been a bit stressful with this deadline, thanks for all you help!

I can't talk to our device through LTE Link Monitor with our own hardware, to do that I need to use a terminal application.

First of all I've moved to a Prolific USB/UART bridge instead of the FTDI one (for now) but it was the same with that bridge.

Here is a test sequence:

1. start up our terminal application (Tera Term VT) and connect to com 9 (Prolific).

2. Power cycle the board.

3. Get boot message on screen.

4. Send AT command and get OK response.

5. Close Tera Term.

6. Connect to same com 9 using LTE monitor.

7. Send AT command get timeout error

8. Power cycle the board.

9. Get boot message

10. Send AT command get timeout error again.

11. Close device in LTE monitor

12. Open Tera Term back up and connect to com 9

13. Send AT command and get OK response.

14. Power cycle the board.

15. Get boot message on screen.

16. Send AT command and get OK response.

17. Close Tera Term.

I've scoped it and I can confirm LTE link monitor is not sending commands but Tera Term is?!

I can't be sure but I think there's something odd happening with LTE Link monitor (V1.1.10). BTW Auto device/port filter is not selected.

Any ideas?

Ian

[Håkon Alseth]

Hi Ian,

 

Yano said:

I've scoped it and I can confirm LTE link monitor is not sending commands but Tera Term is?!

Yano said:

First of all I've moved to a Prolific USB/UART bridge instead of the FTDI one (for now) but it was the same with that bridge.

It is very good to hear that the usb/uart adapters themselves work with various other terminal programs.

 I have created a bug internally on this matter. based on the test procedure that you have gone through, everything points to the LTE Link Monitor not properly handling sending data from the PC -> USB/UART adapter.

 

The best option as of now, is to use a generic terminal application to issue the specific AT commands required by the test house (usually AT%XRFTEST, and maybe a test to connect to a network via AT+CFUN=1).

 

Please let me know if you run into any issues with the testing procedure.

 

Kind regards,

Håkon

[Yano]

Hi Håkon, 

I think I'm OK for the RED testing (now starting Monday) but I also need to get certs into our hardware.

Is there a way to do this using a standard serial terminal?

Could we use USB bridge on an nRF9160-DK and wire it to our hardware and if so what way could we wire it, we have not problem modifying one (cutting tracks etc.).

Also is there a document on the pin re-assignment process (.overlay etc) we had to do? I would like to fully understand the script used.

Thanks

Ian