GSM Modem Sample Project on nRF 5340 App

[code-magic]

Hi. I am trying to get the gsm modem sample project to work with an nRF 5340 app and a Nimbelink LTE modem, NL-SW-LTE-TC4NAG. The only change I made to the project was to add a new file in the boards directory for the 5340. The nrf5340dk_nrf5340_cpuapp.overlay file is below.

The problem is that `uart_dev` is null. The console output I get is below.

I'm not sure if this is a configuration issue or if the modem is not up when `device_get_binding()` is called. What am I missing?

sample_gsm_ppp: Board 'nrf5340dk_nrf5340_cpuapp' APN 'internet' UART 'UART_1' device (nil) (modem_gsm)

&uart0 {
    compatible = "zephyr,gsm-ppp"; // also tried: gsm_ppp,MODEM_GSM_PPP,modem_gsm
    label = "UART_1";
	status = "okay";
	current-speed = <115200>;

	gsm: gsm-modem {
		compatible = "zephyr,gsm-ppp";
		label = "gsm_ppp";
	};
};

[code-magic]

I've made some progress. I created the project in Segger and moved my nrf5340dk_nrf5340_cpuapp.overlay file to the project. I changed the UART label to UART_1. I see that device_get_binding() is now returning a valid device for both uart_dev & gsm_dev. The event_handler() is never called so I guess the modem never connects. Is there a way for me to see what's going on behind the scenes deeper than the debug point never being hit?

I'm confused now because this project accepts UART commands and the modem is also on UART. When I enter a command (resume/suspend) with putty connected to COM4 of the device I get a 'command not found' error. I'm afraid that uart_dev and gsm_dev is the same device according to the overlay file.

Is my overlay file correct? There is a power light on the modem so I know it's on, the event_handler() just isn't being called.