Arduino - an open platform for the development of electronic devices, as well as for teaching programming. Based on the Arduino constantly creating new devices, as well as libraries for working with different peripherals.
There are many different boards Arduino . They differ in characteristics established microcontrollers, size, number of input-output ports, and other parameters, so you can choose the card that best meet the requirements.
Variety boards Arduino
Arduino xxx - standard size, 20 inputs and outputs, full compatibility with all Shield.
ArduinoMega xxx - increased size of 70 inputs and outputs, compatible with all Shield.
ArduinoNano xxx - reducing the size of 22 input-output is not compatible with the Shield.
ArduinoMini xxx - even smaller, 20 I-vyhoov not compatible with the Shield does not have USB.
All of these card have the same number of inputs and outputs collected in the same connectors (for connecting the periphery and Shield), programmable via USB, and have ATMega microcontroller on board.
stands out in this group UNO board and Leonardo. They USB-UART converter is replaced by a microcontroller Atmega8u2, which made it possible to increase the speed of firmware.
In addition, the board is independent Leonardo USB or UART on any of the general public whatsoever pins. PWM output was 1 more analog inputs - 12, supported by virtual COM-port.
Arduino Mega xxx
The series presents models: Mega, Mega2560, Arduino ADK.
Mega built on ATMega1280 and Mega2560 and Arduino ADK - on ATMega2560.
At the board is compatible with almost all the Shield. Are different from ordinary Arduino pinout SPI-interface, because Schild using it with the digital pins 11,12,13, are not compatible.
Conclusions on the cards in this series:
54 digital (of which 15 - PWM);
16 - analog.
128 / 256kb - flash,
Each motherboard has 4 UART.
A small handkerchief with mini-USB. With Shield is not compatible.
Built on the ATmega328.
As a USB-UART bridge used FT232.
Less than ArdinoNano charge.
With the Shield is not compatible. Convenient for installation in the finished product.
At no mini USB - it is programmed using the adapter USB-Serial.
It has a low-power regulator and the LEDs - Only the power and then to the latest versions.
Built on the ATmega328.
All of the "dimensions" and variations of Arduino-board completely compatible with each other. The project is designed for one of them, can be implemented on the other, and none in the code of any scheme to alter anything not necessary.