// From https://embetronicx.com/tutorials/wireless/esp32/idf/esp32-idf-serial-communication-tutorial/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_system.h"
#include "nvs_flash.h"
#include "driver/uart.h"
#include "freertos/queue.h"
#include "esp_log.h"
#include "soc/uart_struct.h"

#define ECHO_TEST_TXD  (1)
#define ECHO_TEST_RXD  (3)

#define BUF_SIZE (1024)

#define BLINK_GPIO 13


static uint8_t s_led_state = 0;

static void configure_led(void)
{
    gpio_reset_pin(BLINK_GPIO);
    /* Set the GPIO as a push/pull output */
    gpio_set_direction(BLINK_GPIO, 1);
}

static void blink_led(void)
{
    /* Set the GPIO level according to the state (LOW or HIGH)*/
    gpio_set_level(BLINK_GPIO, s_led_state);
}

//an example of echo test without hardware flow control on UART1
static void echo_task()
{
    const int uart_num = UART_NUM_1;
    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
    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.
    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, 20 / portTICK_RATE_MS);
        //Write data back to UART
        uart_write_bytes(uart_num, (const char*) data, len);
        blink_led();
        /* Toggle the LED state */
        s_led_state = !s_led_state;
        vTaskDelay(1000 / portTICK_PERIOD_MS);
    }
}




void app_main()
{
    configure_led();
    //A uart read/write example without event queue;
    xTaskCreate(echo_task, "uart_echo_task", 1024, NULL, 10, NULL);
}