Fast data transfer through USB

RE: Fast data transfer through USB

Petar02 — Mon, 25 Aug 2025 12:43:57 GMT

Everything is working fine i just forgot when u start transfer if serial monitor is not open fifo cant "drain", cant send data to PC, so i just added this to my code to wait until serial monitor is open.

uint32_t dtr = 0;
    while (!dtr) {
        uart_line_ctrl_get(usb_uart_device, UART_LINE_CTRL_DTR, &dtr);  //nije radilo dok ne drzis port otvorenim.
        k_sleep(K_MSEC(100)); //12.8ms novi podaci
    }

RE: Fast data transfer through USB

Petar02 — Fri, 15 Aug 2025 13:23:33 GMT

Yes Im using code ftom those examples for USB CDC-ACM and im trying to send 3000B every 13ms, and i should get 200kB/s, but for some reasone Im only getting sizeof(RING_BUF_SIZE)B/s. I modife a little bit a interrupt_handler by changing part for uart_irq_tx_ready

if (uart_irq_tx_ready(dev)) {
            do {
                int rb_len, send_len;
                uint8_t *blk;

                
                rb_len = ring_buf_get_claim(&ringbuf_tx, &blk, 256);
                if (rb_len == 0) {
                    uart_irq_tx_disable(dev);
                    break; 
                }

                
                send_len = uart_fifo_fill(dev, blk, rb_len);

                
                ring_buf_get_finish(&ringbuf_tx, send_len);

                sent_counter += send_len;

                
                if (send_len < rb_len) {
                    break; // FIFO full
                }

            } while (uart_irq_tx_ready(dev)); // prazni dok ima mesta u FIFO-u
        }
    }

Im using send_len to check how many B did I send after 1s.

RE: Fast data transfer through USB

Kenneth — Fri, 15 Aug 2025 10:56:36 GMT

Yes, that should not be a problem no.

Kenneth

RE: Fast data transfer through USB

Petar02 — Fri, 15 Aug 2025 10:32:38 GMT

Can I use uart for logging and USB CDC ACM for data transfer?

RE: Fast data transfer through USB

Kenneth — Thu, 14 Aug 2025 15:31:50 GMT

Hello,

Sorry, I don't understand the debugging messages or comments.

I think the best suggestion I have is to look at the existing USB examples that already exists:
https://docs.nordicsemi.com/bundle/ncs-latest/page/zephyr/samples/index.html#usb_device_support

The USB CDC ACM examples are usually a good starting point since the use bulk transfer, which overall is a quick way to transfer data. Do be aware logging itself can impact execution time depending on interface and configuration.

Kenneth