#include <stdio.h>
#include <stdlib.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/uart.h"
#include "driver/gpio.h"
#include "esp_err.h"

#define ECHO_TEST_TXD (GPIO_NUM_43)
#define ECHO_TEST_RXD (GPIO_NUM_44)
#define UART_NUM      (UART_NUM_1)
#define BUF_SIZE      (1024)

void app_main(void)
{
  uart_config_t uart_config = {
    .baud_rate = 115200,
    .data_bits = UART_DATA_8_BITS,
    .parity = UART_PARITY_DISABLE,
    .stop_bits = UART_STOP_BITS_1,
    .flow_ctrl = UART_HW_FLOWCTRL_DISABLE,
    .rx_flow_ctrl_thresh = 122,
  };
  //Configure UART1 parameters
  ESP_ERROR_CHECK(uart_param_config(UART_NUM, &uart_config));

  //Set UART1 pins(TX: IO4, RX: I05)
  uart_set_pin(UART_NUM, ECHO_TEST_TXD, ECHO_TEST_RXD, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE);

  //Install UART driver (we don't need an event queue here)
  //In this example we don't even use a buffer for sending data.
  ESP_ERROR_CHECK(uart_driver_install(UART_NUM, BUF_SIZE * 2, 0, 0, NULL, 0));

  uint8_t* data = (uint8_t*) malloc(BUF_SIZE);
  while (1) {
    //Read data from UART
    int len = uart_read_bytes(UART_NUM, data, BUF_SIZE, pdMS_TO_TICKS(20));
    //Write data back to UART
    uart_write_bytes(UART_NUM, (const char*) data, len);
    vTaskDelay(pdMS_TO_TICKS(1000));
  }
}