ESP32 DMX transmitting task

dmx.c

#define DMX1_IO (0)
#define DMX1_TX (16)
#define DMX1_RX (32)
#define BUF_SIZE (512)

uint8_t data[513]; // This is a global in this case

/*
So this is an incredibly simple transmit-only DMX task for ESP32 ESP-IDF V4

1. Why the magic number (0x1 << 5) in the inverse?    

V4.0 and V4.1 are renaming various constants.  (0x1 << 5) inverts the TX line and avoids the BS around renamed constants.

2. WTF are you inverting the line?

UART is idle-high.   BREAK is a 172us LOW pulse.  
I could flip this to a GPIO and do the same thing, but inverting the TX pin seemed cleaner and faster.

3. Why is the BREAK 300us?

Made it more reliable than 172, inverting seems to take a while if other things are happening.  

*/
static void dmx_writer_uart1(void *ignore)
{

  uint8_t start_code = 0x00;

  const int uart_num = UART_NUM_1;
  uart_config_t uart_config = {
      .baud_rate = 250000,
      .data_bits = UART_DATA_8_BITS,
      .parity = UART_PARITY_DISABLE,
      .stop_bits = UART_STOP_BITS_2,
      .flow_ctrl = UART_HW_FLOWCTRL_DISABLE,
  };


  /* DMX RX/TX control - HIGH = talking */
  gpio_pad_select_gpio(DMX1_IO);
  gpio_set_direction(DMX1_IO,GPIO_MODE_OUTPUT);
  gpio_set_level(DMX1_IO, 1);

  //Configure UART1 parameters
  uart_param_config(uart_num, &uart_config);
  uart_set_pin(uart_num, DMX1_TX, DMX1_RX, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE);
  uart_driver_install(uart_num, BUF_SIZE * 2, 0, 0, NULL, 0);

  for(;;)
  {
    uart_wait_tx_done(uart_num,1000); // Wait for done
    uart_set_line_inverse(uart_num, (0x1 << 5)); // Set BREAK
    ets_delay_us(300); // Wait 176us
    uart_set_line_inverse(uart_num,  0); // Set MAB
    ets_delay_us(25); // Wait 12us
    uart_write_bytes(uart_num, (const char*) &start_code, 1);  // Send NSC
    uart_write_bytes(uart_num, (const char*) data+1, 512); // Send universe
  }

  vTaskDelete(NULL);

}