app_main.c

#include <FreeRTOS.h>
#include <driver/uart.h>
#include <esp_vfs_dev.h>
#include <stdio.h>

#define UART_RX_BUFFER_SIZE 256
#define UART_TX_BUFFER_SIZE 1024

#define UART_RX_LINE_ENDINGS_MODE ESP_LINE_ENDINGS_CRLF // convert CRLF to LF
#define UART_TX_LINE_ENDINGS_MODE ESP_LINE_ENDINGS_CRLF // convert LF to CRLF

void help()
{
  printf(" help: Show commands\n");
}

void cli()
{
  int c;
  
  printf("> ");

  while ((c = fgetc(stdin)) != EOF) {
    // echo
    fputc(c, stdout);

    if (c == '\b') {
      fprintf(stdout, " \b");
    } else if (c == '\r') {
      continue;
    } else if (c == '\n') {
      return help();
    } else {
    }
  }
}

void app_main()
{
  uart_port_t uart_port = CONFIG_ESP_CONSOLE_UART_NUM;
  uart_config_t uart_config = {
    .baud_rate  = CONFIG_ESP_CONSOLE_UART_BAUDRATE,
    .data_bits  = UART_DATA_8_BITS,
    .parity     = UART_PARITY_DISABLE,
    .stop_bits  = UART_STOP_BITS_1,
  };
  esp_err_t err;

  if ((err = uart_param_config(uart_port, &uart_config))) {
    abort();
  }

  if ((err = uart_driver_install(uart_port, UART_RX_BUFFER_SIZE, UART_TX_BUFFER_SIZE, 0, NULL, 0))) {
    abort();
  }

  // configure stdio to use buffered/interrupt-driven uart driver with CRLF <-> LF conversion
  esp_vfs_dev_uart_use_driver(CONFIG_ESP_CONSOLE_UART_NUM);
  esp_vfs_dev_uart_set_rx_line_endings(UART_RX_LINE_ENDINGS_MODE);
  esp_vfs_dev_uart_set_tx_line_endings(UART_TX_LINE_ENDINGS_MODE);

  // unbuffered input
  setvbuf(stdin, NULL, _IONBF, 0);
  setvbuf(stdout, NULL, _IOLBF, 0);

  while (true) {
    cli();
  }
}