Serial LTE Modem doesn't show what I typed

[Oguzhan Turk]

Is there an option (on cofig files etc.) to set it true for echoing what I typed on Serial LTE Modem firmware application?

[Maria Gilje]

Hello,

Which serial terminal are you using to interface with the nRF9160?

I am not an expert in our cellular solutions, but a local echo seems more dependant on the serial terminal used than the application running on the board.

The Serial Terminal application available through nRF Connect for Desktop is using local echo by default.

Best regards,

Maria

[Oguzhan Turk]

Let's say tio. There is an echo on modem shell but not on slm.

[Maria Gilje]

Hello,

The reason for the lack of echo in the SLM application is that CONFIG_SHELL is disabled in the application. For the Modem Shell sample, CONFIG_SHELL is enabled, which again enables CONFIG_SHELL_ECHO_STATUS by default.

So you will need to add shell functionality to the SLM application to get the functionality you want. CONFIG_SHELL_ECHO_STATUS should be enabled by default, but if it is not you can enable it manually.

Best regards,

Maria

[Oguzhan Turk]

Ok I've added CONFIG_SHELL but now I have another problem now:

normally my uarts were:

chosen {
ncs,slm-ppp-uart = &uart0;
ncs,slm-uart = &uart1;
};

In order to enable shell uart we must add "zephyr,shell-uart = &uart1;" too so:

chosen {
ncs,slm-ppp-uart = &uart0;
zephyr,shell-uart = &uart1;
ncs,slm-uart = &uart1;
};

But then it constantly gives an error:

[Sec Thread] Secure image initializing!
TF-M Float ABI: Hard
Lazy stacking enabled
Booting TF-M v2.0.0


FATAL ERROR: SecureFault
FATAL ERROR: HardFault

I guess it's because of both shell and slm uarts enabled on same uart, therefore if we do:

chosen {
ncs,slm-ppp-uart = &uart0;
zephyr,shell-uart = &uart1;
};

Then, I was able to get shell uart which has echo. But this shell uart was not what I want. Because it was not containing AT host on it. What I want is simply ncs,slm-uart with echo functionality.

[Oguzhan Turk]

For the referance this line of modem_shell firmware application does it: github.com/.../at_cmd_mode.c

[Michal]

Hello, we would recommend using a terminal that supports local echo.

Looks like tio has an ongoing issue on that, so best use something else, like maybe picocom: https://github.com/tio/tio/issues/92

Best regards,

Michal

[Oguzhan Turk]

Ok, picocom worked fine with parameter "-c" and even tio worked fine with "-e". But, I wrote an executable communicating with modem through UART with socket operations. And my parser expects the first line of answer (what I read from buffer) is what I sent. And It works fine with modem shell's at_cmd_mode. Because firmware application itself has local echo. I also mentioned in this answer: RE: Serial LTE Modem doesn't show what I typed 

The question is is there way to do it on serial lte modem as well? Maybe with assigning some variable on conf file etc?

[Oguzhan Turk]

I created a pull request for this purpose: github.com/.../18823