Use the Debug in connector P3 on nrf9160DK to read/write AT commands

[erumed]

Hi!

I am developing on a custom board and only have the Debug in connector P3 from nrf9160dk to debug the board. I want to send AT commands to configure the modem and will be using the AT_client sample to do this. What configuration do I need to use P3 to do this?

Found that you are able to debug using the connector here https://infocenter.nordicsemi.com/pdf/nRF91_DK_User_Guide_v0.7.1.pdf page 22

I am really thankful for any help!

/Beginner developer

[Didrik Rokhaug]

Hi,

No, you can not use the at_client sample to receive AT commands over P3.

As it is currently written, the at_client sample only supports UART.

However, you should be able to write a program that receives the AT commands over RTT, and sends them to the modem. You can then connect a debugger to P3, and use that connection to send AT commands.

Best regards,

Didrik

[erumed]

Ok, thank you! 

Is there any information or links on how to use RTT to recieve and then send to the modem? 

And also, does this mean that you cannot read or send to the serial line through P3?

Any help in code to this would be so helpful, thanks!

/Ellinor

[Didrik Rokhaug]

erumed said:

And also, does this mean that you cannot read or send to the serial line through P3?

 As the connector is only connected to the debug pins of the nRF9160, no you can not use it to send UART.

 

erumed said:

Is there any information or links on how to use RTT to recieve and then send to the modem? 

 You can find the RTT API in modules/debug/segger/SEGGER/SEGGER_RTT.h.

Segger seems to have some more documentation for the API here: RTT API functions.

In addition, you can use the RTT backend for Zephyr's shell as inspiration: zephyr/subsys/shell/shell_rtt.c

That should let you send and receive data to the application core.

Then, you want to re-write nrf/lib/at_host/at_host.c to use RTT instead of UART (or, add an alternative implementation and use a Kconfig symbol to choose which one is used).