ESP32 Forum

Posted: **Sat Jul 09, 2022 4:01 pm**

With the ESP32-Arduino, I learned that we can exchange data with USB-CDC just as we do with a physical UART port,
using the same functions as with a physical UART port, such as Serial.print() and Serial.read().

I also learned that ESP-IDF allows interactive data exchange between the PC and ESP32-C3 using the esp_console component.

However, in order to exchange data in a free format, for example without line feed codes,
I would like to communicate with ESP32-C3+ESP-IDF using USB-CDC in the same way as with a regular UART.

Is there any easy way to Tx/Rx data via USB-CDC using ESP32-C3 + ESP-IDF?

Posted: **Thu Jan 19, 2023 12:57 pm**

I found it on the website https://blog.csdn.net/ai_ljh/article/details/126999395
It works.

Code: [Select all] [Expand/Collapse]

#include <stdio.h>
#include "sdkconfig.h" 
#include "freertos/FreeRTOS.h" 
#include "freertos/task.h" 
#include "esp_system.h" 
#include "esp_spi_flash.h" 
#include "string.h" 
#include "hal/usb_serial_jtag_ll.h" 
void mytask1(void *pvParameter)
{
    uint8_t *rxbuf;
    int cnt;
    rxbuf = (uint8_t *)malloc(64);
    int rxcnt;
 
    while (1)
    {
        if (usb_serial_jtag_ll_rxfifo_data_available()) 
        { 
            rxcnt = usb_serial_jtag_ll_read_rxfifo(rxbuf,64);
            cnt = (int)usb_serial_jtag_ll_write_txfifo((const uint8_t *)rxbuf, rxcnt);
            usb_serial_jtag_ll_txfifo_flush(); 
            //printf("Send %d characters to host \n", cnt);
        }
        vTaskDelay(pdMS_TO_TICKS(10));
    }
    free(rxbuf);
    vTaskDelete(NULL); 
} 
 
void app_main(void) 
{
    xTaskCreate(mytask1, "mytask1", 1024 * 5, NULL, 1, NULL);
}

GeSHi © Codebox Plus Extension

Posted: **Fri Jan 20, 2023 1:11 pm**

Hi,

the datasheet say:

Code: Select all

USB - GPIO18 and GPIO19 are USB pins. The pull-up value of a USB pin is controlled by the pin’s pull-up
value together with USB pull-up value. If any of the two pull-up values is 1, the pin’s pull-up resistor will be
enabled. The pull-up resistors of USB pins are controlled by USB_SERIAL_JTAG_DP_PULLUP bit.

so, try to clear USB_SERIAL_JTAG_DP_PULLUP bit and then just use standard uart functions (uart_param_config, uart_set_pin, uart_driver_install, uart_write_bytes, uart_read_bytes, etc)

Code: Select all

CLEAR_PERI_REG_MASK(USB_SERIAL_JTAG_CONF0_REG, USB_SERIAL_JTAG_DP_PULLUP);

ESP32 Forum

Can the ESP32-C3's USB-CDC port be used like a UART?

Can the ESP32-C3's USB-CDC port be used like a UART?

Re: Can the ESP32-C3's USB-CDC port be used like a UART?

Re: Can the ESP32-C3's USB-CDC port be used like a UART?