RE: Console output over USB

KevinG — Fri, 02 Feb 2024 19:49:01 GMT

Thanks for the great information. Using the example in the link, I was able to use the USB for console output by making the following changes:

prj.conf

CONFIG_LOG=y
CONFIG_LOG_BACKEND_SHOW_COLOR=y
CONFIG_LOG_MODE_DEFERRED=y
CONFIG_USB_DEVICE_STACK_NEXT=y
CONFIG_STDOUT_CONSOLE=y
CONFIG_UART_LINE_CTRL=y
CONFIG_USBD_CDC_ACM_CLASS=y
CONFIG_USBD_LOG_LEVEL_WRN=y
CONFIG_UDC_DRIVER_LOG_LEVEL_WRN=y
CONFIG_UART_CONSOLE=y

Added to my dts for my custom board, but could be added to an overlay for a DK:

	chosen {
		...
		zephyr,console = &cdc_acm_uart0;
	};
	
	&usbd {
	status = "okay";
	cdc_acm_uart0: cdc_acm_uart0 {
		compatible = "zephyr,cdc-acm-uart";
	};
};

And in my main.c file:

#include <zephyr/kernel.h>
#include <zephyr/device.h>
#include <zephyr/devicetree.h>
#include <zephyr/logging/log.h>
#include <zephyr/usb/usb_device.h>
#include <zephyr/usb/usbd.h>
#include <zephyr/drivers/uart.h>

...


BUILD_ASSERT(DT_NODE_HAS_COMPAT(DT_CHOSEN(zephyr_console), zephyr_cdc_acm_uart), "Console device is not ACM CDC UART device");

USBD_CONFIGURATION_DEFINE(usbd_config_1, USB_SCD_SELF_POWERED, 200);

USBD_DESC_LANG_DEFINE(usb_lang);
USBD_DESC_MANUFACTURER_DEFINE(usb_mfr, "CompanyName");
USBD_DESC_PRODUCT_DEFINE(usb_product, "ProjectName");
USBD_DESC_SERIAL_NUMBER_DEFINE(usb_sn, "1234SERIALNUMBER");

USBD_DEVICE_DEFINE(my_usbd, DEVICE_DT_GET(DT_NODELABEL(usbd)), 0x2fe3, 0x0001);

static int enable_usb_device_next(void)
{
	int err;

	err = usbd_add_descriptor(&my_usbd, &usb_lang);
	if (err) {
		return err;
	}

	err = usbd_add_descriptor(&my_usbd, &usb_mfr);
	if (err) {
		return err;
	}

	err = usbd_add_descriptor(&my_usbd, &usb_product);
	if (err) {
		return err;
	}

	err = usbd_add_descriptor(&my_usbd, &usb_sn);
	if (err) {
		return err;
	}

	err = usbd_add_configuration(&my_usbd, &usbd_config_1);
	if (err) {
		return err;
	}

	err = usbd_register_class(&my_usbd, "cdc_acm_0", 1);
	if (err) {
		return err;
	}

	err = usbd_init(&my_usbd);
	if (err) {
		return err;
	}

	err = usbd_enable(&my_usbd);
	if (err) {
		return err;
	}

	return 0;
}
//End Logging Setup


int main(void)
{

    ...
    
     //Init USB Console
    enable_usb_device_next();
    const struct device *const usbDevice = DEVICE_DT_GET(DT_CHOSEN(zephyr_console));
	uint32_t dtr = 0;

    ...
    
    while(1) {
        //obviously change this to work for your needs
        if(!dtr) {
            uart_line_ctrl_get(usbDevice, UART_LINE_CTRL_DTR, &dtr);
        }

		k_msleep(SLEEP_TIME_MS);
    }

RE: Console output over USB

Håkon Alseth — Mon, 22 Jan 2024 11:18:43 GMT

Hi,

Logging over USB uses CDC, which enumerates as a COM-port in the OS even though all communication is USB.

To route a CDC ACM to the console, you can have a look at the zephyr/samples/subsys/usb/console sample, specifically in the app.overlay file:

https://github.com/nrfconnect/sdk-zephyr/blob/main/samples/subsys/usb/console/app.overlay

Kind regards,

Håkon