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atmega328-pu-microcontroller

4 min read

Important Note

This entire repo was AI created - including all of the data within. The intent was to A) help me with my personal electronics inventory; and B) see how I could use AI to make that process a bit easier. DO NOT TRUST!

ATmega328-PU - 8-bit AVR RISC Microcontroller

Details

Description

The ATmega328-PU is an 8-bit AVR RISC-based microcontroller that combines 32KB of in-system programmable Flash memory with read-while-write capabilities, 1KB EEPROM, 2KB SRAM, 23 general purpose I/O lines, 32 general purpose working registers, three flexible timer/counters with compare modes, internal and external interrupts, a serial programmable USART, a byte-oriented 2-wire serial interface, an SPI serial port, a 6-channel 10-bit ADC, a programmable watchdog timer with internal oscillator, and five software selectable power saving modes. This is the same microcontroller used in the Arduino Uno, making it fully compatible with Arduino IDE and libraries.

Specifications

Core Specifications

  • Architecture: 8-bit AVR enhanced RISC
  • Operating Voltage: 1.8V ~ 5.5V
  • Clock Speed: Up to 20 MHz (16 MHz typical for Arduino applications)
  • Performance: 20 MIPS at 20 MHz
  • Operating Temperature: -40°C to +85°C

Memory

  • Program Memory (Flash): 32KB (with 0.5KB used by bootloader in Arduino)
  • SRAM: 2KB
  • EEPROM: 1KB
  • Endurance: 10,000 write/erase cycles (Flash), 100,000 write/erase cycles (EEPROM)

I/O and Peripherals

  • Digital I/O Pins: 23 (22 on Arduino Uno due to crystal)
  • PWM Channels: 6 (8-bit)
  • ADC Channels: 6 (10-bit, 15 kSPS)
  • Analog Comparator: 1
  • Timers: 3 (two 8-bit, one 16-bit)

Communication Interfaces

  • USART: 1 (serial communication)
  • SPI: 1 (Serial Peripheral Interface)
  • I2C (TWI): 1 (Two-Wire Interface)

Pinout Diagram

    ATmega328-PU 28-Pin DIP
    ┌─────────────────────┐
PC6 │1  (RESET)        28│ PC5 (ADC5/SCL)
PD0 │2  (RXD)          27│ PC4 (ADC4/SDA)
PD1 │3  (TXD)          26│ PC3 (ADC3)
PD2 │4  (INT0)         25│ PC2 (ADC2)
PD3 │5  (INT1/OC2B)    24│ PC1 (ADC1)
PD4 │6  (T0/XCK)       23│ PC0 (ADC0)
VCC │7                 22│ GND
GND │8                 21│ AREF
PB6 │9  (TOSC1/XTAL1)  20│ AVCC
PB7 │10 (TOSC2/XTAL2)  19│ PB5 (SCK)
PD5 │11 (T1/OC0B)      18│ PB4 (MISO)
PD6 │12 (AIN0/OC0A)    17│ PB3 (MOSI/OC2A)
PD7 │13 (AIN1)         16│ PB2 (SS/OC1B)
PB0 │14 (ICP1/CLKO)    15│ PB1 (OC1A)
    └─────────────────────┘

Arduino Pin Mapping

ATmega328 PinArduino PinFunction
PD0Digital 0RX (Serial)
PD1Digital 1TX (Serial)
PD2Digital 2INT0
PD3Digital 3PWM, INT1
PD4Digital 4-
PD5Digital 5PWM
PD6Digital 6PWM
PD7Digital 7-
PB0Digital 8-
PB1Digital 9PWM
PB2Digital 10PWM, SS
PB3Digital 11PWM, MOSI
PB4Digital 12MISO
PB5Digital 13SCK, LED
PC0Analog 0ADC0
PC1Analog 1ADC1
PC2Analog 2ADC2
PC3Analog 3ADC3
PC4Analog 4ADC4, SDA
PC5Analog 5ADC5, SCL

Applications

Common use cases for the ATmega328-PU:

  • Arduino Uno replacement or standalone projects
  • Custom Arduino-compatible boards
  • Embedded control systems
  • Sensor data acquisition projects
  • Motor control applications
  • Home automation systems
  • Educational microcontroller projects
  • Prototyping and breadboard development

Programming Examples

Arduino IDE Setup

// Basic blink program for standalone ATmega328
void setup() {
  pinMode(13, OUTPUT); // PB5 - same as Arduino Uno LED pin
}
 
void loop() {
  digitalWrite(13, HIGH);
  delay(1000);
  digitalWrite(13, LOW);
  delay(1000);
}

Serial Communication

void setup() {
  Serial.begin(9600);
}
 
void loop() {
  Serial.println("Hello from ATmega328-PU!");
  delay(1000);
}

ADC Reading

void setup() {
  Serial.begin(9600);
}
 
void loop() {
  int sensorValue = analogRead(A0);
  float voltage = sensorValue * (5.0 / 1023.0);
  Serial.print("Sensor: ");
  Serial.print(sensorValue);
  Serial.print(" Voltage: ");
  Serial.println(voltage);
  delay(500);
}

Circuit Examples

Minimal Arduino-Compatible Circuit

ATmega328-PU Minimal Circuit:
- Pin 7 (VCC) ---- +5V
- Pin 8, 22 (GND) ---- Ground
- Pin 20 (AVCC) ---- +5V
- Pin 21 (AREF) ---- +5V (or external reference)
- Pin 1 (RESET) ---- 10kΩ pullup to +5V
- Pin 9, 10 (XTAL) ---- 16MHz crystal + 22pF capacitors to ground
- 0.1µF decoupling capacitor between VCC and GND

ISP Programming Header

6-Pin ISP Header:
1. MISO (Pin 18) ---- PB4
2. VCC ---- +5V
3. SCK (Pin 19) ---- PB5
4. MOSI (Pin 17) ---- PB3
5. RESET (Pin 1) ---- PC6
6. GND ---- Ground

Technical Notes

Important considerations for the ATmega328-PU:

  • Bootloader: Requires Arduino bootloader for Arduino IDE compatibility
  • Crystal: 16MHz crystal recommended for Arduino timing compatibility
  • Power Supply: 5V recommended for Arduino compatibility, but can operate 1.8V-5.5V
  • Programming: Can be programmed via ISP, Arduino as ISP, or USB-to-serial with bootloader
  • Fuse Settings: Default fuses may need modification for external crystal operation
  • Brown-out Detection: Built-in brown-out detection helps prevent corruption

Tags

microcontroller, avr, arduino-compatible, 8-bit, atmega328, dip-28 cabinet-3 bin-40 status-available

Notes

The ATmega328-PU is one of the most popular microcontrollers for hobbyist and educational projects due to its use in the Arduino Uno. Having 11 of these chips provides excellent flexibility for creating custom Arduino-compatible projects, standalone embedded systems, or as replacements for Arduino Uno boards. The DIP package makes them perfect for breadboard prototyping and through-hole PCB designs. These microcontrollers offer a great balance of features, ease of use, and community support through the Arduino ecosystem. They’re ideal for learning embedded programming and for projects that need more customization than standard Arduino boards provide.

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