Logging over USB CDC ACM with nRF52840 Dongle

[Crexodon]

Hello,

I'm currently running into issues when using the Logging Interface with USB CDC ACM. I tried to combine the cdc_acm sample and the console sample into one application with logging messages. The dongle gets recognized as a cdc acm device on my host machine and I get my messages echoed back, but I don't get any logging messages. When I build the application for the nRF52840 DK it works correctly and outputs logging messages on the nrf52840 USB Port while also echoing back my input.

Left terminal is the dongle, right terminal is the DK

Overlay file:

 / {
	chosen {
		zephyr,console = &cdc_acm_uart0;
	};
};

&zephyr_udc0 {
	cdc_acm_uart0: cdc_acm_uart0 {
		compatible = "zephyr,cdc-acm-uart";
	};
};

prj.conf file

# USB
CONFIG_STDOUT_CONSOLE=y
CONFIG_USB_DEVICE_STACK=y
CONFIG_USB_DEVICE_PRODUCT="Zephyr CDC ACM sample"
CONFIG_USB_DEVICE_PID=0x0001
CONFIG_USB_DEVICE_INITIALIZE_AT_BOOT=n

# Serial
CONFIG_SERIAL=y
CONFIG_CONSOLE=y
CONFIG_UART_CONSOLE=y
CONFIG_UART_INTERRUPT_DRIVEN=y
CONFIG_UART_LINE_CTRL=y

# Logger
CONFIG_LOG=y
CONFIG_USB_DRIVER_LOG_LEVEL_ERR=y
CONFIG_USB_DEVICE_LOG_LEVEL_ERR=y

CONFIG_LOG_BACKEND_UART=y
CONFIG_LOG_MODE_IMMEDIATE=y

main.c file

#include <stdio.h>
#include <string.h>
#include <zephyr/device.h>
#include <zephyr/drivers/uart.h>
#include <zephyr/kernel.h>
#include <zephyr/sys/ring_buffer.h>

#include <zephyr/usb/usb_device.h>
#include <zephyr/usb/usbd.h>
#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(cdc_acm_echo, LOG_LEVEL_INF);

#define RING_BUF_SIZE 1024
uint8_t ring_buffer[RING_BUF_SIZE];

struct ring_buf ringbuf;

static void interrupt_handler(const struct device *dev, void *user_data)
{
	ARG_UNUSED(user_data);

	while (uart_irq_update(dev) && uart_irq_is_pending(dev)) {
		if (uart_irq_rx_ready(dev)) {
			int recv_len, rb_len;
			uint8_t buffer[64];
			size_t len = MIN(ring_buf_space_get(&ringbuf),
					 sizeof(buffer));

			recv_len = uart_fifo_read(dev, buffer, len);
			if (recv_len < 0) {
				LOG_ERR("Failed to read UART FIFO");
				recv_len = 0;
			};

			rb_len = ring_buf_put(&ringbuf, buffer, recv_len);
			if (rb_len < recv_len) {
				LOG_ERR("Drop %u bytes", recv_len - rb_len);
			}

			LOG_DBG("tty fifo -> ringbuf %d bytes", rb_len);
			if (rb_len) {
				uart_irq_tx_enable(dev);
			}
		}

		if (uart_irq_tx_ready(dev)) {
			uint8_t buffer[64];
			int rb_len, send_len;

			rb_len = ring_buf_get(&ringbuf, buffer, sizeof(buffer));
			if (!rb_len) {
				LOG_DBG("Ring buffer empty, disable TX IRQ");
				uart_irq_tx_disable(dev);
				continue;
			}

			send_len = uart_fifo_fill(dev, buffer, rb_len);
			if (send_len < rb_len) {
				LOG_ERR("Drop %d bytes", rb_len - send_len);
			}

			LOG_DBG("ringbuf -> tty fifo %d bytes", send_len);
		}
	}
}

int main(void)
{
	const struct device *dev;
	uint32_t baudrate, dtr = 0U;
	int ret;

	dev = DEVICE_DT_GET_ONE(zephyr_cdc_acm_uart);
	if (!device_is_ready(dev)) {
		LOG_ERR("CDC ACM device not ready");
		return 0;
	}

	ret = usb_enable(NULL);

	if (ret != 0) {
		LOG_ERR("Failed to enable USB");
		return 0;
	}

	ring_buf_init(&ringbuf, sizeof(ring_buffer), ring_buffer);

	LOG_INF("Wait for DTR");

	while (true) {
		uart_line_ctrl_get(dev, UART_LINE_CTRL_DTR, &dtr);
		if (dtr) {
			break;
		} else {
			/* Give CPU resources to low priority threads. */
			k_sleep(K_MSEC(100));
		}
	}

	LOG_INF("DTR set");

	/* They are optional, we use them to test the interrupt endpoint */
	ret = uart_line_ctrl_set(dev, UART_LINE_CTRL_DCD, 1);
	if (ret) {
		LOG_WRN("Failed to set DCD, ret code %d", ret);
	}

	ret = uart_line_ctrl_set(dev, UART_LINE_CTRL_DSR, 1);
	if (ret) {
		LOG_WRN("Failed to set DSR, ret code %d", ret);
	}

	/* Wait 100ms for the host to do all settings */
	k_msleep(100);

	ret = uart_line_ctrl_get(dev, UART_LINE_CTRL_BAUD_RATE, &baudrate);
	if (ret) {
		LOG_WRN("Failed to get baudrate, ret code %d", ret);
	} else {
		LOG_INF("Baudrate detected: %d", baudrate);
	}

	uart_irq_callback_set(dev, interrupt_handler);

	/* Enable rx interrupts */
	uart_irq_rx_enable(dev);
	
	
	while(true) {
		LOG_INF("ABC");
		k_sleep(K_MSEC(500));
	}
}

The main.c file is basically the same as the cdc_acm sample but with a while(true) at the end for continuous log output.

I've tried multiple variations in the prj.conf file for the logger, usb and uart but none get the logging working on the dongle. Am I missing something else or is there some setting inside the board file for the dongle that I may have to override?