Arduino Basics

Hardware Anatomy

Arduino Hardware Anatomy

Ports Voltage and Current

Port Name	Voltage and Current
VIN	7-12V, ~1A
USB Port	5V, ~1A
Digital pins	5V, ~40mA
5V pin	~800mA

The ~ infront of the current means the value is approximate.

Difference between Vin and 5V pin

The Vin pin is used to supply an external voltage to the Arduino board. Its usage is that you can power the Arduino by supplying an external power source (like a battery or a power adapter) to the Vin pin.

The 5V pin can either be an input or an output depending on how you're powering the board.

• Output: When the Arduino is powered through the USB port or the Vin pin, the 5V pin provides a regulated 5V output that can be used to power other components like sensors or modules.

• Input: You can also directly supply 5V to the 5V pin to power the Arduino, bypassing the onboard voltage regulator.

Digital Pins

Port Name	Purpose
Pins 0-1	Serial CCOM
Pin 13	LED pin
Pin (~)	PWM

API

Basic Digital Input/Output (I/O)

void pinMode(pin, OUTPUT);

void digitalWrite(pin, HIGH);

int digitalRead(pin);

Timing

void delay(millisecs);

void delayMicroseconds(microsecs);

unsigned long millis(); // overflow after around 50 days

unsigned long micros(); // overflow after around 1 hour

In Arudino, the millis() and micros() are built-in functions that return the number of milliseconds/microseconds that have passed since the Arduino board began running the current program (since the board was powered on or reset). And below is an example to blink the LED.

const int ledPin = 13; // Pin for the LED
unsigned long previousMillis = 0; // Store the last time the LED was updated
const long interval = 1000; // Interval of 1 second (1000 ms)

void setup() {
  pinMode(ledPin, OUTPUT);
}

void loop() {
  unsigned long currentMillis = millis();

  if (currentMillis - previousMillis >= interval) {
    // Save the last time the LED was toggled
    previousMillis = currentMillis;

    // Toggle the LED state
    digitalWrite(ledPin, !digitalRead(ledPin));
  }
}

In Arduino, the unit is not set in the code.The unit depends on how you use the variable in your code. In the example above, we are using it with millis(), so its unit is milliseconds.

Examples

LED Blinking

void setup() {
    pinMode(13, OUTPUT);
}

void loop() {
    digitalWrite(13, HIGH);
    delay(1000);
    digitalWrite(13, LOW);
    delay(1000);
}

In this example, we can get a glimpse of how the delay() function works, it actually pauses the execution of the program for a specified amount of time. For example, at line 7, we execute the delay(1000), notice that the unit is milliseconds. Now the program is paused and the LED is ON because that after line 6, no instruction is executed, so LED will remain ON.