//Receive data from App, Send to Arduino Serial Monitor (PC) (e.g. Arduino UNO)
#include <SoftwareSerial.h>
SoftwareSerial Serial1(10, 11); // RX, TX

//vars
unsigned long lgUpdateTime;
char val[];

void setup()
{
         Serial.begin(9600);
         Serial1.begin(9600);
         lgUpdateTime = millis();
}

void loop()
{
         //Excute loop every 1/2 second
	     if(millis() - lgUpdateTime > 500) 
         {
               lgUpdateTime = millis();
               
               if (Serial1.available() > 0)
               {
                    //Read Data From App
                    val = Serial1.read();
               
                    //Send to Arduino Serial Monitor on PC (via USB cable)
                    Serial.println(val)
               }
         }
}