ATMega328P-UP Microcontroller


ATMega328P-UP Microcontroller

ATMega328P Microcontroller is high performance, low power controller from Microchip. The ATMega328P-UP is 8-bits microcontroller based on AVR RISC architecture. The most popular of all AVR controllers due to the usage in Arduino boards.

ATMega328P-UP Microcontroller Pinout Configuration

ATMega328P-UP is a 28 pins Microcontroller chip as shown in pin diagram above. Some of the pins has additional functions as describe in the table below. We will describe functions of each pin in below table.

Pin No. Pin name Description Secondary Function
1 PC6 (RESET) Pin6 of  PORTC Pin by default is used as RESET pin. PC6 can only be used as I/O pin when RSTDISBL Fuse is programmed.
2 PD0 (RXD) Pin0  of  PORTD RXD (Data Input Pin for USART)USART Serial Communication Interface[Can be used for programming]
3 PD1 (TXD) Pin1 of  PORTD TXD (Data Output Pin for USART)USART Serial Communication Interface[Can be used for programming] INT2( External Interrupt 2 Input)
4 PD2 (INT0) Pin2  of  PORTD External Interrupt source 0 
5 PD3 (INT1/OC2B) Pin3  of  PORTD External Interrupt source1 OC2B(PWM – Timer/Counter2 Output Compare Match B Output)
6 PD4 (XCK/T0) Pin4  of  PORTD T0( Timer0 External Counter Input)XCK ( USART External Clock I/O)
7 VCC   Connected to positive voltage
8 GND   Connected to ground
9 PB6 (XTAL1/TOSC1) Pin6  of  PORTB XTAL1 (Chip Clock Oscillator pin 1 or External clock input)TOSC1 (Timer Oscillator pin 1)
10 PB7 (XTAL2/TOSC2) Pin7  of  PORTB XTAL2 (Chip Clock Oscillator pin 2)TOSC2 (Timer Oscillator pin 2)
11 PD5(T1/OC0B) Pin5 of  PORTD T1(Timer1 External Counter Input) OC0B(PWM – Timer/Counter0 Output Compare Match B Output)
12 PD6 (AIN0/OC0A) Pin6  of  PORTD AIN0(Analog Comparator Positive I/P) OC0A(PWM – Timer/Counter0 Output Compare Match A Output)
13 PD7 (AIN1) Pin7  of  PORTD AIN1(Analog Comparator Negative I/P) 
14 PB0 (ICP1/CLKO) Pin0  of  PORTB ICP1(Timer/Counter1 Input Capture Pin) CLKO (Divided System Clock. The divided system clock can be output on the PB0 pin)
15 PB1 (OC1A) Pin1  of  PORTB OC1A (Timer/Counter1 Output Compare Match A Output)
16 PB2 (SS/OC1B) Pin2  of  PORTB SS (SPI Slave Select Input).  This pin is low when controller acts as slave.[Serial Peripheral Interface (SPI) for programming] OC1B (Timer/Counter1 Output Compare Match B Output)
17 PB3 (MOSI/OC2A) Pin3  of  PORTB MOSI (Master Output Slave Input). When controller acts as slave, the data is received by this pin. [Serial Peripheral Interface (SPI) for programming]OC2 (Timer/Counter2 Output Compare Match Output)
18 PB4 (MISO) Pin4  of  PORTB MISO (Master Input Slave Output). When controller acts as slave, the data is sent to master by this controller through this pin. [Serial Peripheral Interface (SPI) for programming]
19 PB5 (SCK) Pin5  of  PORTB SCK (SPI Bus Serial Clock). This is the clock shared between this controller and other system for accurate data transfer.[Serial Peripheral Interface (SPI) for programming]
20 AVCC   Power for Internal ADC Converter
21 AREF   Analog Reference Pin for ADC
23 PC0 (ADC0) Pin0  of  PORTC  ADC0 (ADC Input Channel 0)
24 PC1 (ADC1) Pin1  of  PORTC ADC1 (ADC Input Channel 1)
25 PC2 (ADC2) Pin2  of  PORTC  ADC2 (ADC Input Channel 2)
26 PC3 (ADC3) Pin3  of  PORTC  ADC3 (ADC Input Channel 3)
27 PC4 (ADC4/SDA) Pin4  of  PORTC ADC4 (ADC Input Channel 4)SDA (Two-wire Serial Bus Data Input/output Line)
28 PC5 (ADC5/SCL) Pin5  of  PORTC ADC5 (ADC Input Channel 5)SCL (Two-wire Serial Bus Clock Line)


ATMega328P-UP – Simplified Features

CPU 8-bit AVR
Number of Pins 28
Operating Voltage (V) +1.8 V TO +5.5V
Number of programmable  I/O lines 23
Communication Interface Master/Slave SPI Serial Interface(17,18,19 PINS) [Can be used for programming this controller]Programmable Serial USART(2,3 PINS) [Can be used for programming this controller]Two-wire Serial Interface(27,28  PINS)[Can be used to connect peripheral devices like Servos, sensors and memory devices]
JTAG Interface Not available
ADC Module 6channels, 10-bit resolution ADC
Timer Module Two 8-bit counters with Separate Prescaler and compare mode, One 16-bit counter with Separate Prescaler, compare mode and capture mode.
Analog Comparators 1(12,13 PINS)
DAC Module Nil
PWM channels 6
External Oscillator 0-4MHz @ 1.8V to 5.5V0-10MHz @ 2.7V to 5.5V0-20MHz @ 4.5V to 5.5V
Internal Oscillator 8MHz  Calibrated Internal Oscillator
Program Memory Type Flash
Program Memory or Flash memory 32Kbytes[10000 write/erase cycles]
CPU Speed 1MIPS for 1MHz
RAM 2Kbytes Internal SRAM
Watchdog Timer Programmable Watchdog Timer with Separate On-chipOscillator
Program Lock Yes
Power Save Modes Six Modes[Idle, ADC Noise Reduction, Power-save, Power-down, Standby and Extended Standby]
Operating Temperature -40°C to +105°C(+105 being absolute maximum, -40 being absolute minimum)

Note: Complete technical details can be found in the ATMega328P-UP Datasheet.

How to Use ATMega328P-UP Microcontroller

ATMega328 is used similar to any other controller. All there to do is programming. Controller simply executes the program provided by us at any instant. Without programming controller simply stays put without doing anything.

To program the controller is done by writing the appropriate program file in the ATMega328P-UP FLASH memory. After dumping this program code, the controller executes this code and provides appropriate response.

Entire process of using an ATMega328P-UP microcontroller goes like this:

  1. List the functions to be executed by controller.
  2. Write the functions in programming language in IDE programs. You can download the IDE program for free in company websites. IDE program for AVR controllers is ‘ATMEL STUDIO’. Link for ATMEL STUDIO is given below. (Usually Atmel Studio 6.0 for Windows 7, Atmel Studio 7 for Windows 10
  3. ATMega328P-UP programming can be done in ARDUINO IDE.
  4. After writing the program, compile it to eliminate errors.
  5. Make the IDE generate HEX file for the written program after compiling.
  6. This HEX file contains the machine code which should be written in controller flash memory.
  7. Choose the programming device (usually SPI programmer made for AVR controllers) which establishes communication between PC and ATMega328P-UP. You can program ATMega328P-UP using Arduino Uno board.
  8. Run the programmer software and choose the appropriate hex file.
  9. Burn the HEX file of written program in ATMega328P-UP flash memory using this program.
  10. Disconnect the programmer, connect the appropriate peripherals for the controller and get the system started.

How to Use ATMega328P-UP in Arduino Platform

The ATMega328P-UP is used in Arduino Uno and Arduino Nano boards, you can directly replace the arduino board with ATmega328 chip. For that first you need to install the Arduino bootloader into the chip. This IC with bootloader can be placed on Arduino Uno board and burn the program into it. The Arduino program is burnt into the IC, it can be removed and used in place of Arduino board, along with a Crystal oscillator and other components as required for the project. Below is the pin mapping between Arduino Uno and ATMega328P-UP chip.

ATMEGA328P-UP Microcontroller and the Arduino pin out. | Download Scientific Diagram


There are hundreds of applications for ATMega328P-UP:

  • Used in Arduino Uno, Arduino Nano and Arduino Micro boards.
  • Industrial control systems.
  • SMPS and Power Regulation systems.
  • Digital data processing.
  • Analog signal measuring and manipulations.
  • Embedded systems like coffee machine, vending machine.
  • Motor control systems.
  • Display units.
  • Peripheral Interface system.


All measurements are in millimeters.

ATMega328P Dimensions

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