Arduino Mega Tutorial – Pinout & Schematics

First of all, Why Arduino Mega?

When cheaper boards are available, why go with Arduino Mega? The main reason behind this is the additional features that are inbuilt with this board. First feature is the large I/O system design with inbuilt 16 analog transducers and 54 digital transducers that supports with USART and other communication modes. Secondly, it has inbuilt RTC and other features like analog comparator, advanced timer, interrupt for controller wakeup mechanism to save more power and fast speed with 16 Mhz crystal clock to get 16 MIBS. It has more than 5 pins for Vcc and Gnd to connect other devices to Arduino Mega.

Arduino Mega Tutorial – Pinout & Schematics

Other features include JTAG support for programming, debugging and troubleshooting. With large FLASH memory and SRAM, this board can handle large system program with ease. It is also compatible with different type of boards like high-level signal (5V) or low-level signal (3.3V) with I/O ref pin.

Brownout and watchdog help to make system more reliable and robust. It supports ICSP as well as USB microcontroller programming with PC.

Arduino Mega 2560 is also packed with additional features like Analog Comparator, External Interrupt & Software Interrupt, Power Saving Mode, Inbuilt Temperature Sensor, RTC and more.

Arduino Mega Pinout

Arduino Mega Pin Diagram

Controller Pins:

RESET: (Reset input) A low level on this pin for longer than the 4 clock cycle will generate a reset. Arduino Mega has inbuilt reset circuit with push button to reset system and this pin can be used by other devices to reset controller.

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XTAL1,XTAL2: Crystal (16Mhz) is connected to supply clock for controller with 2 bypass capacitor to ground.

AREF: This pin is used, when we use Adc for analog to digital conversion with external reference voltage for conversion and don’t want to use internal 1.1V or 5v reference.

Digital pins (70):
Digital pins (0-53) + Analog (0-15) = Total Digital I/O pins.

Digital Pins: From 0-53(digital) and 0-15(analog) can be use as input or output for digital transducer and output devices by pinMode() for pin direction, digtalWrite() to write pin and digitalRead() to read pin status.


Output devices : Relay, LED, buzzer, LCD and others.

Input devices: digital thermistor, push button, ultrasonic sensor, joystick and others

Arduino Mega Tutorial – Pinout & Schematics


  • Output low signal on Arduino mega board



  • Input read signal on Arduino mega board



 Analog Pins (16):

Analog pins: From 0-15(analog) can be used as analog input pin for adc, if not used than it work as normal digital pin. It can be used by pinMode() for pin direction, analogRead() to read pin status and get digital value for analog signal, care must be taken for internal or external reference voltage selection and Aref pin.

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