Cookbooks
Arduino
Chapter 9. Testing and Debugging
Printing debug output

Arduino:
Printing debug output

How to:

Let’s get down to brass tacks. Say you want to print “Hello, world!” every second. Here’s the code snippet:

void setup() {
  Serial.begin(9600);  // Start the serial communication
}

void loop() {
  Serial.println("Hello, world!");  // Print the message
  delay(1000);  // Wait for a second
}

Fire up the Serial Monitor in the Arduino IDE and watch the words tumble down like clockwork. Sample output:

Hello, world!
Hello, world!
Hello, world!
...

Deep Dive

Before Serial became our trusty sidekick, folks used blinking LEDs to communicate - the Stone Age of debugging. Then, serious debug hardware came along, but it was pricey. Serial.print() and its relatives now let us sling texts onto the screen at blistering speed, cheap as chips.

Alternatives? Well, you’ve got LCDs, logging to SD cards, even Bluetooth for the wire-averse. Each method has its quirks; Serial is just the straight shooter - simple, direct, always there.

Under the hood, Serial.print() converts your data into bytes that scuttle along the USB to your computer. This happens over hardware (UART) or software-emulated (SoftSerial) serial ports. It’s reliable, but hogging the port with too much data can jam your program’s flow, so sprinkle serial prints like you’re seasoning a steak, not flooding a soup.

See Also

For those hungry for more:

Using a debugger