How could I communicate through UART on platform STM32L433? (Ubuntu)

[kp008114]

Hello everyone,

I finshed installing the SDK, west and DTC, then I accomplished the first sample Hello world. I used "screen" to show the words on terminal. It's good. However, I would like to communicate to MCU through UART that means not only MCU can send me some words but also I can send some words to MCU and it can respond something to me based on those words. Unfortunately, I have no idea how to achieve this.

I used to developing the program in Wondows STMCubeMX, but I have to switch to Linux becasue of some reasons. May some one give me ideas? And if "screen" is a good tool to interact with MCU, may I sending words to MCU through "screen"?

platform: STM32L433
OS: Ubuntu

[erwango]

You can test samples/subsys/shell/shell_module.
On my side, i'm using minicom instead of screen, but it should be equivalent.

[erwango]

By default, samples/subsys/shell/shell_module will offer a communication link (both RX/TX) over UART.
Have you had a try? If yes, can you explain what is missing regarding the use case you expect?

[kp008114]

Finshed build and flash.
Command to connect uart: sudo screen /dev/ttyUSB0 115200,cs8
The terminal shows nothing.
Here are some questions:

1. Where can I know which pins the current uart is using? I checked nucleo_l433rc_p.dts
   The content as follows. Does that mean I've to hang up the PA9 and PA10 to uart transceiver accordingly?

        pinctrl-0 = <&usart1_tx_pa9 &usart1_rx_pa10>;
        pinctrl-names = "default";
        current-speed = <115200>;

2. How does the main function know which uart is using? I cannot find any word like &uart1, &uart2, etc. in main.c file.
   Is the following line figuring out it?
   dev = DEVICE_DT_GET(DT_CHOSEN(zephyr_shell_uart));
3. The terminal, where I input screen command, didn't show anything. Neither I keyed in some words and pressed Enter.

[erwango]

1. Unless you changed it, default is lpuart1 actually:

        zephyr,console = &lpuart1;
        zephyr,shell-uart = &lpuart1;

2. Binding is done thanks to zephyr,shell-uart = &lpuart1;

3. STLink tty is ACM0, so you should use screen /dev/ttyACM0 115200,cs8. This being said, I'm using minicom : minicom -D /dev/ttyACM0

[kp008114]

I found you're the same person replying me in discord #stm32. Thank you so much.
May I change the default console to uart? Or how can the lpuart(ttyACM0) and uart(ttyUSB0) coexist? Because I have a uart transceiver that is seperated from the usb cable for lpuart.

[erwango]

If you have a nucleo_l433rc_p board, I'd suggest making it work the default way to start from a known working basis.
Then, modify as you wish.