Connecting nRF9151 DKs via UART

Question

Nordic TS,

I'm trying to establish a link between two 9151 DK through which I can pass messages. I'm trying to create a setup where DK 1 receives messages using a DECT NR+ link and forwards them to DK2 to transmit on LTE-M. I'm a newbie/intermediate with the Nordic development environment, and I have a number of questions on how to do this. I'd appreciate it if you can help with the following questions about hardware, software and configuration.

1. Is the best comm to establish the link between DK1 and DK2 a UART?

2. If so, which is the best choice of UART number? My understanding is that UART0 is used by the USB and UART1 is also used (but I'm unsure). Is UART2 a good choice?

3. For the choice of UARTx, what are the proper pins to use?

4. If I want to make the comm very reliable, should the RTS and CTS pins be used or are they not necessary?

5. Is a DT overlay file needed? Some videos and posts indicate that it is, but I'm unclear on the the exact changes needed. I saw the followiing in a video for configuring UART1, but I'm unsure if it is correct (pls correct as necessary):

&uart1 {

compatible = "nordic,nrf-uart";

status = "okay";

current-speed = <115200>; // Set baud rate

tx-pin = <6>; // TX pin (P0.06)

rx-pin = <8>; // RX pin (P0.08)

};

What would be the needed overlay for the use of UART2?

6. What changes/additions are needed for the prj.conf? I saw the following in a video but I'm again unsure as to whether it is correct and complete (pls correct as necessary):

CONFIG_SERIAL=y

CONFIG_UART_ASYNC_API=y

CONFIG_UART_0_INTERRUPT_DRIVEN=n

CONFIG_UART_0_ASYNC=y

What is needed to use UART2?

7. In the application code, how is the UARTx referenced? Is the following correct?

const struct device *uart1 = DEVICE_DT_GET(DT_NODELABEL(uart1));

const struct device *uart2 = DEVICE_DT_GET(DT_NODELABEL(uart2));

Thank you in advance for your help.

Best,

Steven Gordon