Serial communication always reporting seemingly random numbers

Hi everybody,

trying to get my first project using serial communication up and running on my new Arduino Uno.

I have tried a couple of example programs, but I am getting nothing from the serial read, and then I discovered that as soon as I begin serial communications, the serial monitor reports nothing but seemingly random numbers.

I am now using a very bare-bones program:

void setup() {
 Serial.begin(9600);       // use the serial port
}

void loop() {

}

Running this code, and opening the serial monitor, I am seeing a bunch of randomness, looking like this:

4515

4474 40 3349 45 33319 316 3314318

07 307306330 30 31313306 333233113314 19 332310 331320 16 330305 011 313314 316 3331315103304

31336 320 31332134 030304330633019 332 11 008 30319 321 3316 314 310330503319130530310 3331832313 306 3053314 303192310 308 315 3320323 2 93130363304 1314 32020 320330309 311 3133 30530630 6 3

12 306 30533033 3303 337 33 3 133143113030305337

As you can see, I have no Serial.read() anywhere in my code - is it really correct that the serial monitor should even be showing stuff at all? And how can I get my serial communications to report what I am actually attempting to get it to report?

Serial.begin does not start communicating it just sets up registers and stuff. Random numbers normally mean an unconnected or floating input somewhere.

In fact what you report is not possible so you must be doing something that you are not reporting. That sketch should do nothing.

Looks like the wires aren't connected.

This is a programming question anyway. Thread moved.

That’s right, the sketch should do nothing, but as you can see I am getting weird input.

The numbers are the same no matter if/how I connect the wires.

the sketch should do nothing, but as you can see I am getting weird input.

That should be a weird output from the arduino.

As I said that will not happen if you run that sketch and it is wired up correctly.

It could be that your board is damaged, do you see the TX light flash when the serial monitor is receiving this?

We need much more information:-
What OS are you running on the PC?
Will the arduino program up a blinking LED sketch?
Have you set the speed on the serial monitor to be the same as the arduino sketch?
What sort of arduino are you using?
Have you a photo of your setup?
Have you selected the right serial port in the tools menu?

What happens to the serial monitor when you disconnect the arduino?