Removed HardwareSerial.h include. Switched RTS pin to GPIO 4 for broader compatability.

Author: econeale

libraries/ESP32/examples/Serial/RS485_Echo_Demo/RS485_Echo_Demo.ino

@@ -11,13 +11,11 @@
   using an RS485 tranciver, connect another serial monitor to the RS485 port. Entering data on one terminal
   should be displayed on the other terminal.
 */
-
-#include <HardwareSerial.h>
 #include "hal/uart_types.h"
 
 #define RS485_RX_PIN 16
 #define RS485_TX_PIN 5
-#define RS485_RTS_PIN 37
+#define RS485_RTS_PIN 4
 
 #define RS485 Serial1