Serial Monitor not displaying anything

Question

I have a very basic script that is supposed to display something to the serial monitor but no matter what I try the serial monitor won't display anything...I;ve watched about 5 tutorials now and each one has failed to display anything. Any ideas what I'm doing wrong?

Here is my code:

char rx_byte;
void setup() {
 Serial.begin(115200);
 pinMode(13, OUTPUT);
 digitalWrite(13, LOW);
}
void loop() {
 if(Serial.available() > 0){
 rx_byte = Serial.read();
 Serial.print("You typed: ");
 Serial.println(rx_byte);
 digitalWrite(13, HIGH);
 delay(1000);
 digitalWrite(13, LOW);
 }
}

• Nick Gammon: Are you typing anything into the serial monitor? What baud rate is the serial monitor set to?
• mr-matt: I'm typing just the number 1 and 0, according to the tutorial I watched that should turn the LED on/off. The baud rate is set the same as what is in my code.
• Nick Gammon: I'm typing just the number 1 and 0 - and then you pressed the Send button? Please add Serial.println ("Hello, world"); after the Serial.begin line and see if that appears in the serial monitor.
• mr-matt: Yes then I pressed the send button. I tried putting that line in after Serial.begin and still nothing...
• Nick Gammon: Well, solve that first. No point typing and pressing Send if nothing appears. What Arduino do you have? What version of the IDE?

Answer 1

Which one are you using?

The one closest to the reset button, I believe its the native...

This is more confusing than I realized. The Due has two ports:

Due ports

---

Programming port

For programming, the programming port is easiest to use. And you can "talk" to the serial port using Serial, like this:

void setup ()
 {
 Serial.begin (115200);
 Serial.println ("Hello, world!");
 } // end of setup
void loop ()
 {
 } // end of loop

---

Native USB port

This lets you emulate USB devices (eg. keyboard, mice). However if you want to use it for Serial communications you need to use a different class SerialUSB like this:

void setup ()
 {
 SerialUSB.begin(115200);
 while (!SerialUSB) ; // wait for it to become ready
 SerialUSB.println ("Starting ...");
 } // end of setup
unsigned long i;
void loop ()
 {
 SerialUSB.print ("Hello, world! Count = ");
 SerialUSB.println (++i);
 delay (1000);
 } // end of loop

It also helps to wait for the serial port to become ready, as I did in setup. Otherwise you may miss the first 10 lines or so of serial output.

Answer 2

You have to change the baud rate at the right bottom corner of the serial monitor to 115200 which you have assigned initially. I have tested it and It doesn't matter if its int/char

• mr-matt: I have done that, still no luck.

Answer 3

Try replacing the line char rx_byte; with int rx_byte=0;. Use Serial.println(rx_byte,DEC);

int rx_byte=0;
void setup() {
 Serial.begin(115200);
 pinMode(13, OUTPUT);
 digitalWrite(13, LOW);
}
void loop() {
 if(Serial.available() > 0){
 rx_byte = Serial.read();
 Serial.print("You typed: ");
 Serial.println(rx_byte,DEC);
 digitalWrite(13, HIGH);
 delay(1000);
 digitalWrite(13, LOW);
 }
}

• mr-matt: Same again, nothing...