SoftwareSerialPassthrough.ino

#include <SoftwareSerial.h>

//                      RX, TX on Arduino
SoftwareSerial mySerial(8, 9);

void setup()
{
  Serial.begin(9600);
  mySerial.begin(9600);
}

int isInput = 0;
int isOutput = 0;
void loop()
{
  /* send everything received from the hardware uart to usb serial & vv */
  if (Serial.available() > 0) {
    char ch = Serial.read();
    mySerial.print(ch);
  }
  
  if (mySerial.available() > 0) {
    char ch = mySerial.read();
    if( ch ){
      Serial.print(ch);
    }
  }
  
  isInput --;
  isOutput = 0;
}