Arduino Mega

A new bigger Arduino has been spotted in the wild.

Arduino Mega

Arduino Mega

The Arduino Mega is the new larger brother of the Arduino Duemilanove microcontroller board. Instead of being based on a 28-pin Atmel ATmega168 or ATmega368 the Mega is based on the larger 100-pin ATmega1280 device.

The Arduino Mega board has 54 digital input/output pins (of which 14 can be used as PWM outputs), 16 analog inputs, 4 UARTs (hardware serial ports), a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button.

The Mega is compatible with most shields designed for the Arduino however a few differences to note from Atmega1280 and ATmega386 are:

  • only 6 of the external interrupts are available (the ATmega1280 has 8).
  • 4 “new” external interrupts are on dual-purpose pins. 2 are on the TX/RX pins for Uart#1 (pins 18-19), and 2 are on the I2C pins (pins 20-21).
  • the I2C pins have moved (from 4-5 to 20-21). Any Arduino shield, or project, using I2C will require re-work for the MEGA.
  • the timers associated with specific PWM pins have changed, Interrupt 0 and 1 are on pins 20 and 21, Input capture for timer1 is not available, and pins 14 through 19 are no longer shared with the analog pins.
  • My Arduino Mega arrived last Saturday 28th March from This was a pretty quick service from Coolcomponents as the Mega was only announced on Thursday 26th March.

    The additional I/O will be very useful, as will the larger available board area => bigger shields but the Arduino Mega still have the problem of available coast area for I/O connectors.

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