Introduction

ATMega328P is a commonly used microcontroller, and its pinout refers to the pin layout and function description of the microcontroller. The importance of the ATMega328P pinout is that it specifies the specific positions and functions of the input and output interfaces, power supply, and ground pins of the microcontroller, and is an important basis for circuit design and programming.

Table of Content

ATMega328P Pinout Frame Diagram

The features of ATMega328P Pinout include moderate pin count, rich functions, and flexible use. ATMega328P Pinout is divided into many types, including digital pins, analog pins, power pins, and special function pins.

The ATmega328P chip has 28 pins, and the usage and pin diagram configuration details of each pin are shown in the figure below:

ATMega328P Pinout

I/O Pins

This microcontroller has three digital ports (B, C, D), namely PORTB, PORTC and PORTD. All these pins can be used as digital input/output. Best of all, every port can be used for other purposes. To use them as output/input or any other function, they should be defined first, otherwise, all I/O pins will not have any default function. The controller’s digital I/O pins are:

PBO -GPIO14

PB1 -GPIO15

PB2 - GPIO16

PB3- GPIO17

PB4 - GPIO18

PB5 - GPIO19

PB6- GPIO9

PB7 - GPIO10.

PC0 - GPIO23

PC1 - GPIO24

PC2 -GPIO25

PC3 - GPIO26

PC4 - GPIO27

PC5 - GPIO28

PC6 -GPIO1

PD0 - GPIO2

PD1 - GPIO3

PD2- GPIO4

PD3 - GPIO5

PD4 - GPIO6

PD5 - GPIO11

PD6 -GPIO12

PD7 -GPI013

Interrupt pin

Most electrical functions require an interruption to the system to operate, such as AC dimmers, etc. ATmega328P provides support for 2 interrupt pins within the controller, which can be used to draw the attention of the CPU at any time. The interrupt pins of ATmega328P are as follows:

• INo -GPIO4
• IN1 -GPIO5

UART communication module

While there are multiple communication systems within this device and modules, the most common is USART. It is one of the simplest and easiest methods for most developers and systems to implement and understand. In this method, two wires are used to send and receive data. The USART pins of ATmega328P are:

• RX -GPIO2
• TX -GPIO3

Data can be sent at a specified send rate within the controller, but an external clock pin can also be used to keep the data synchronized:

• XCK -GPIO6

The USART/UART communication system can be used to program microcontrollers.

SPI communication

It is one of the best serial communication systems for multiple peripheral situations. The SPI protocol allows multiple devices to communicate using the same channel. It consists of four wires, two for data sending, and one for clock, but the fourth wire is used to select the peripheral called select slave. When more peripherals are selected as slaves, the number of pins will increase. The SPI pins of the microcontroller are:

• MOSI - GPIO17
• MISO - GPIO18
• SS - GPIO16
• SCK -GPIO19

I2C communication module

Most peripherals come with IPC communication, which is a time-specific method. The I-C protocol uses only one data line and one clock line. The data lines will transmit and receive data, and the clock lines will send clock pulses to keep the data in sync. The I2C pins on the microcontroller are:

• SDA -GPIO27
• SCL -GPIO28

Timer module

The ATtiny328P has two internal timers that can be used to make counters and generate pulses. Both timers rely on oscillators. Both timers can operate using internal and external clocks, but they also have an internal pin that can count based on external pulses. All these pins in microcontroller ATmega328P are as follows:

• T0 -GPIO6
• T1 -GPIO11
• TOSC1 -GPIO9
• TOSC2-GPIO10
• ICP1 -GPIO

Among them, ICP1 is the input capture pin, which can capture external pulses at specific time intervals. An input pulse on this pin generates a timestamp that can tell when an external signal is received.

System clock

The internal clock and external clock pulses can be divided by prescalers and their values can be received at external pins. The external pins for the divided clock pulse are:

• CLKo - GPIO14

Comparator module

The microcontroller has an internal comparator module for analog signals. This module takes inputs in inverting and non-inverting forms and can be further used for any internal purpose and can also be used to generate output signals. The comparator pins of the microcontroller are as follows:

• ANO (positive)-GPIO12
• AN1(negative)-GPIO13

Capture/Compare/PWM Channel

ATmega328P has six capture/compare/PWM pins for generating the required time pulse-based signal, it uses a prescaler to divide the time pulse, all these pins are:

OCOB -GPIO11

OCOA -GPIO12

OC1A - GPIO15

OC1B - GPIO16

OC2A -GPIO17

OC2B -GPIO5

ADC channel

ATmega328P has 6 ADC channels that can convert analog signals into digital signals. The analog converter needs to be activated first via its power pin (AVCC). The ADC channel uses the supply voltage as a reference to differentiate between different levels of the analog signal. The analog pins of the controller are:

ADCO - GPIO23

ADC1 -GPIO24

ADC2 - GPIO25

ADC3 - GPIO26

ADC4 -GPIO27

ADC5 -GPIO28

AVCC-Pin 20

AREF pin

Sometimes the analog signal voltage fluctuates, but the controller is constantly measuring based on the controller's power input. The analog voltage reference AREF will be used to measure it through any other power input or the power supply of an analog signal-generating device. This pin will detect the maximum value of the analog signal and then be able to give the correct output. The AREF pin in ATmega328P is:

• AREF -GPIO21

RESET

In ATmega328, some resets can restart the microcontroller in certain situations. Among all these resets, there is an external reset that can use an external signal to reset the device:

• RESET -GPIO1

Power

Every controller requires power to operate, and there is always a power input pin. The number of power pins of ATmega328P is three. One pin is for voltage and the remaining two are for common ground. Both ground pins are connected internally and it doesn't matter which one is used. The power pins of the microcontroller are:

• l VCC-pin 7
• l GND - Pin 8, Pin 22

Oscillator

The controller is equipped with an 8MHz variable oscillator. However, it can also use an external oscillator up to 40MHz. To use an external oscillator, an oscillator pin is required for input and output signals. These pins are as follows:

• XTAL1 -GPIO9
• XTAL2- GPIO10

Specific applications of ATMega328P Pinout

In circuit design, it is necessary to select appropriate pins for configuration and use according to specific needs. In programming, you need to understand the specific functions of each pin and the corresponding input and output signals to correctly control and use these pins. Like Arduino, the pins become specific to their function. When using the ATmega328P's compiler, almost all pins can be used as GPIO. However, when using Arduino, each pin will only perform a specific function, but the controller can still perform all operations like the ATmega328P.

Conclusion

ATMega328P Pinout is a crucial foundation for circuit design and programming. It is necessary to understand and master its characteristics, classification, and specific application methods. In practical applications, it is essentical to use the ATMega328P Pinout flexibly and conduct circuit design and programming according to the actual situation to achieve more efficient and stable project development.