Arduino Nano V3 & ATmega328P

Digital GPIO Pins (D0 - D13)

14 digital I/O pins operating at 5V logic with up to 20mA current capability per pin.

• Pins D3, D5, D6, D9, D10, D11 provide 8-bit hardware PWM output (analogWrite)
• Pins D2 and D3 support hardware external interrupts (INT0 and INT1)
• Pin D13 drives the onboard user LED via an internal series resistor

Analog Inputs (A0 - A7)

8 dedicated 10-bit successive approximation ADC channels converting voltages from 0 to 5V.

• Converts 0–5V inputs into discrete integers from 0 to 1023 (4.88 mV per step)
• Pins A4 (SDA) and A5 (SCL) also host the hardware I2C bus
• Pins A6 and A7 are pure analog inputs (cannot be configured as digital outputs)

Power & Communication Rails

Dedicated power regulation pins, hardware serial buses, and system reset lines.

• VIN pin accepts 7V to 12V unregulated DC input from battery packs or wall adapters
• 5V pin outputs regulated 5V (or accepts regulated 5V when USB is disconnected)
• 3V3 pin outputs up to 50mA from the onboard FTDI / CH340 regulator

Hardware UART

D0 (RX) & D1 (TX)

Full-duplex serial communication up to 115200 baud connected to the USB-to-UART chip and PC Serial Monitor.

I2C Bus (TWI)

A4 (SDA) & A5 (SCL)

Two-wire synchronous serial interface supporting multiple sensors and OLED displays on a shared 2-wire bus.

SPI Interface

D10 (SS), D11 (MOSI), D12 (MISO), D13 (SCK)

High-speed synchronous serial peripheral interface running up to 8 MHz for SD card modules, RF radios, and shift registers.

PWM Waveforms

D3, D5, D6, D9, D10, D11

Hardware pulse-width modulation operating at 490 Hz (D3, D9, D10, D11) and 980 Hz (D5, D6) for motor speed and LED dimming.

External Interrupts

D2 (INT0) & D3 (INT1)

Triggers ISR callback functions instantly on LOW, CHANGE, RISING, or FALLING signal transitions with zero polling overhead.

ICSP Programming

MISO, MOSI, SCK, RESET, VCC, GND

In-circuit serial programming header for direct ISP programmers like USBasp, AVRISP mkII, or another Arduino.

Bypass analogWrite() to configure Timer0, Timer1, or Timer2 directly for custom frequencies up to 62.5 kHz for silent motor drives.

Pro tip: Timer0 controls millis() and delay(); modifying Timer0 alters Arduino system timing functions.

All 22 digital and analog pins can trigger Pin Change Interrupts across 3 port groups (PCINT0, PCINT1, PCINT2) for rotary encoders.

Pro tip: Use PCINT when external interrupt pins D2 and D3 are already occupied by high-priority sensors.

Enter Power-down mode using avr/sleep.h to drop current consumption from 15mA down to under 50µA on battery-powered projects.

Pro tip: Disconnect the power LED resistor and remove the USB-to-UART chip on clones for true sub-100µA battery runtimes.

Manipulate PORTB, PORTC, and PORTD directly to toggle pins in 62.5 nanoseconds (single clock cycle)—over 40x faster than digitalWrite().

Pro tip: Direct port writes allow writing an entire 8-bit parallel bus simultaneously in a single CPU cycle.

Store calibration offsets, Wi-Fi credentials, and system states in 1024 bytes of non-volatile EEPROM with 100,000 write cycle endurance.

Pro tip: Use EEPROM.update() instead of EEPROM.write() to prevent unnecessary cell wear when data has not changed.

Prevent system lockups in remote deployments. If firmware hangs in an infinite loop, the internal 128 kHz watchdog resets the MCU.

Pro tip: Ensure your bootloader clears MCUSR on startup; older bootloaders can enter infinite reset loops if WDT triggers.

Breadboard Prototyping & Education

Standard 0.1-inch header pitch fits cleanly across breadboard power rails, making it ideal for electronics labs and classroom exercises.

Compact Robotics & Mechatronics

Controls line-following robots, dual H-bridge motor drivers, and ultrasonic obstacle avoidance in miniature vehicle chassis.

Custom MIDI Controllers & Macropads

Reads banks of analog potentiometers and mechanical switches to emit MIDI notes or control synthesizers and stage lighting.

Multi-Sensor Data Loggers

Utilizes 8 analog input channels (including dedicated A6 and A7) to monitor environmental, soil, and battery parameters simultaneously.

// Arduino Nano - High-precision analog reading with running average
const int sensorPin = A0;
const int ledPin = 13;
const int numReadings = 10;
int readings[numReadings];
int readIndex = 0;
long total = 0;

void setup() {
  Serial.begin(115200);
  pinMode(ledPin, OUTPUT);
  for (int i = 0; i < numReadings; i++) readings[i] = 0;
  Serial.println("Arduino Nano Analog Logger Online");
}

void loop() {
  total -= readings[readIndex];
  readings[readIndex] = analogRead(sensorPin);
  total += readings[readIndex];
  readIndex = (readIndex + 1) % numReadings;

  float avgRaw = (float)total / numReadings;
  float voltage = avgRaw * (5.0 / 1023.0);

  Serial.print("Filtered ADC: ");
  Serial.print(avgRaw, 1);
  Serial.print(" | Voltage: ");
  Serial.print(voltage, 3);
  Serial.println(" V");

  digitalWrite(ledPin, avgRaw > 512 ? HIGH : LOW);
  delay(100);
}

#include <avr/io.h>
#include <avr/interrupt.h>

// Toggle Pin D13 (PB5) using Timer1 CTC Interrupt
ISR(TIMER1_COMPA_vect) {
  PORTB ^= (1 << PB5); // Toggle LED in 1 CPU cycle
}

int main(void) {
  // Set Pin 13 (PB5) as OUTPUT
  DDRB |= (1 << DDB5);

  // Configure Timer1 for 1 Hz blink (CTC Mode)
  TCCR1B |= (1 << WGM12);               // CTC mode
  TCCR1B |= (1 << CS12) | (1 << CS10);   // Prescaler 1024
  OCR1A = 15624;                        // (16MHz / (1024 * 1Hz)) - 1
  TIMSK1 |= (1 << OCIE1A);              // Enable Timer Compare Interrupt

  sei(); // Enable global interrupts

  while (1) {
    // Main loop remains 100% free for sensor logic
  }
}