How can I “reset” an Arduino board?

Question

I\'ve uploaded a sketch to an Arduino Uno whose loop is something like this:

void loop(){
    Serial.println(\"Hello, World!\");
}

So, now,

Answer 1

For Arduino Yún users, try uploading via Ethernet/Wi-Fi (menu Tools → Port).

I had exactly the same problem, and I tried pretty much everything (apart from burning a new bootloader). I am surprised it worked, but I've uploaded an empty sketch without any problem.

Answer 2

1. Unplug Tx from the microcontroller
2. Insert USB cable
3. Wait until full load
4. Connect Rx with hardware
5. Compile empty sketch in prosses and unconnect tx (don't worry about the error)
6. Connect Rx with hardware
7. Compile empty sketch
8. Power off and connect Tx

Answer 3

Based on my experience with the communication already in use or blocked, I would say that the program you are interfacing with still has the communication open.

I also found that if you disconnect the USB cable it will rest the communication. It is not the greatest solution, but it solves the problem.

Answer 4

If you still have the serial console open, it will reserve the serial port. Close it, and try again.

Answer 5

1. First of all, connect your Arduino device.
2. Then go to Device Manager and uninstall the driver.
3. Now remove your Arduino device.
4. Again connect you Arduino device to your system.
5. Now install your driver (which you have uninstalled earlier).

It will free your port for sure.

Answer 6

Make sure you plug the Arduino directly into the computer and not through a hub. Using a hub will give you this error.