The ATmega328P is a high-performance, low-power CMOS 8-bit microcontroller based on the AVR enhanced RISC architecture. By executing powerful instructions in a single clock cycle, the device achieves throughputs approaching 1 MIPS per MHz, allowing the system designer to optimize power consumption versus processing speed. This specific chip is world-renowned as the heart of the Arduino Uno, making it the industry standard for hobbyists, engineers, and educational purposes. It features 32KB of programmable flash memory, 2KB of SRAM, and 1KB of EEPROM, providing a robust platform for everything from simple LED blinking to complex industrial automation and sensor fusion tasks.
ATmega328P Pinout (TO-28)
The ATmega328P is commonly found in the 28-pin Dual In-line Package (DIP) which is ideal for breadboarding and through-hole PCB designs. Below is the functional pin mapping for this package.
| Pin Number | Pin Name | Description |
| 1 | PC6 (RESET) | Reset Pin (Active Low) |
| 2 | PD0 (RXD) | Port D Pin 0 / USART Receive |
| 3 | PD1 (TXD) | Port D Pin 1 / USART Transmit |
| 4 | PD2 (INT0) | Port D Pin 2 / External Interrupt 0 |
| 5 | PD3 (INT1) | Port D Pin 3 / External Interrupt 1 |
| 6 | PD4 (XCK/T0) | Port D Pin 4 / External Counter Source |
| 7 | VCC | Digital Supply Voltage |
| 8 | GND | Ground |
| 9 | PB6 (XTAL1) | Port B Pin 6 / Crystal Oscillator Input |
| 10 | PB7 (XTAL2) | Port B Pin 7 / Crystal Oscillator Output |
| 11 | PD5 (T1) | Port D Pin 5 / External Counter Source |
| 12 | PD6 (AIN0) | Port D Pin 6 / Analog Comparator Input 0 |
| 13 | PD7 (AIN1) | Port D Pin 7 / Analog Comparator Input 1 |
| 14 | PB0 (ICP1) | Port B Pin 0 / Input Capture Pin |
| 15 | PB1 (OC1A) | Port B Pin 1 / PWM Output A |
| 16 | PB2 (SS) | Port B Pin 2 / SPI Slave Select |
| 17 | PB3 (MOSI) | Port B Pin 3 / SPI Master Out Slave In |
| 18 | PB4 (MISO) | Port B Pin 4 / SPI Master In Slave Out |
| 19 | PB5 (SCK) | Port B Pin 5 / SPI Serial Clock |
| 20 | AVCC | Supply Voltage for ADC |
| 21 | AREF | Analog Reference Pin |
| 22 | GND | Ground |
| 23 | PC0 (ADC0) | Port C Pin 0 / Analog Input 0 |
| 24 | PC1 (ADC1) | Port C Pin 1 / Analog Input 1 |
| 25 | PC2 (ADC2) | Port C Pin 2 / Analog Input 2 |
| 26 | PC3 (ADC3) | Port C Pin 3 / Analog Input 3 |
| 27 | PC4 (ADC4/SDA) | Port C Pin 4 / I2C Serial Data |
| 28 | PC5 (ADC5/SCL) | Port C Pin 5 / I2C Serial Clock |
Technical Specifications – maximum
- Operating Voltage: 1.8V to 5.5V
- Flash Memory: 32 KB (of which 0.5 KB used by bootloader)
- SRAM: 2 KB
- EEPROM: 1 KB
- Clock Speed: 0 to 20 MHz
- DC Current per I/O Pin: 40.0 mA
- DC Current VCC and GND Pins: 200.0 mA
- Operating Temperature: -40°C to +85°C
- Power Consumption at 1MHz, 1.8V: 0.2 mA
- Analog-to-Digital Converter (ADC): 10-bit resolution, 8 channels (6 in PDIP)
- PWM Channels: 6
- Communication Interfaces: Master/Slave SPI, I2C (TWI), USART
Key Features & Benefits
- Advanced RISC Architecture: 131 powerful instructions, most executed in a single clock cycle, providing high throughput.
- picopower® Technology: Optimized for extremely low power consumption in sleep modes, making it ideal for battery-operated devices.
- In-System Programmability: Supports SPI and specialized bootloaders to update firmware without removing the chip.
- Robust Peripherals: Includes two 8-bit Timer/Counters and one 16-bit Timer/Counter with separate prescalers and compare modes.
- Self-Programming Flash: Features a Read-While-Write capability for safer and more efficient memory management.
- Wide Operating Range: Reliable performance across a broad voltage and temperature spectrum.
Common Applications
- Arduino Projects: Serving as the primary MCU for the Uno, Nano, and Pro Mini boards.
- Home Automation: Controlling smart lights, temperature monitoring systems, and security locks.
- Industrial Control: Managing motor speeds, relay switching, and automated assembly line feedback.
- Consumer Electronics: Used in hand-held gaming devices, digital clocks, and remote controls.
- Data Logging: Collecting sensor data from environmental or medical devices and storing it in EEPROM.
- Educational Kits: Teaching embedded C programming and digital electronics fundamentals.
ATmega328P Equivalent & Substitutes
- ATmega328PB: An enhanced version with more PWM channels and dual interfaces.
- ATmega168: Half the flash memory (16KB) but pin-compatible.
- ATmega88: Lower flash capacity (8KB) for simpler tasks.
- ATmega48: Minimal flash (4KB) for cost-sensitive high-volume production.
- ATTiny85: A smaller 8-pin alternative for very space-constrained projects.
Related Tutorials on ElxHub – with links
- Selection Guide: Ultimate Microcontroller Selection Guide
- FUTURE TUTORIALS:
- How to burn Arduino Bootloader on ATmega328P
- Interfacing 16×2 LCD with ATmega328P using C
- Low Power Sleep Modes in AVR Microcontrollers
- PWM Generation on ATmega328P: A Step-by-Step Guide
Conclusion
The ATmega328P remains the “gold standard” of 8-bit microcontrollers because it strikes a perfect balance between complexity and ease of use. Whether you are building a commercial product or a weekend DIY project, its massive community support, extensive documentation, and reliable performance ensure that your design has a solid foundation. Its versatility in handling both analog and digital signals, combined with power-saving features, makes it a timeless choice in the ever-evolving world of embedded systems.
Download the Microcontroller’s Datasheet pdf
focus keyword: ATmega328P Datasheet seo title: ATmega328P Pinout, Features, and Technical Specifications | ElxHub slug: atmega328p-microcontroller-datasheet meta description: Explore the complete ATmega328P datasheet including pinout diagrams, technical specs, and common applications. The definitive guide for Arduino’s core MCU.