How do I find the base hardware configuration that Nordic code samples were built using

[dnear1]

I'm working on the NRF Connect SDK v1.6.1 and building the zephyr\samples\net\gsm_modem project, since I'm trying to set up and operate a Nimbelink modem.  The code references uart_1, but I can't find where the pin definitions are that UART_1 is bound to.  The only reference I can find is in nrf5340_cpuapp_peripherals.dtsi but it doesn't define any pins..

Do I just need to add an overlay file and define RX/TX/CTS/RTS pins for UART1?  Is there any sample hardware project that this code was tested against?

[Carl Richard]

Hi!

You can find the UART1 configuration in the board files of the nRF5340DK. Specifically nrf5340_cpuapp_common.dts. The configuration there is:

arduino_serial: &uart1 {
	compatible = "nordic,nrf-uarte";
	current-speed = <115200>;
	tx-pin = <33>;
	rx-pin = <32>;
};

As you can see you must add an overlay to specify the CTS/RTS pins. 

The test conditions for the sample are specified in the Requirements section of the sample description. Quoting:

• GSM modem card. The sample has been tested with SIMCOM SIM808 card. All GSM modem cards should work as long as they support AT+CGDCONT command.

• Almost any Zephyr enabled board with sufficient resources can be used. The sample has been tested with reel board.

Note that this sample is maintained by Zephyr, not us.

Best regards,
Carl Richard

[dnear1]

Is it possible to use the one net core uart for the modem instead of the app core?  Or would that break the things under chosen in the cpunet.dts?

[Carl Richard]

It should be fine to use the net core UART, just note that it will require the application running on the net core to handle communication with the modem. If you use hci_rpmsg for BLE operation, the modem sample must be integrated with the hci_rpmsg sample.

Best regards,
Carl Richard