Which Arduino to buy? A variety of Arduino boards is available based on the type of the microcontroller they have. They all are programmed through Arduino IDE. They are different in terms of their number of inputs/outputs, operating voltages (3.5V or 5v), form factor, speed etc.
Arduino boards with ATMEGA328 microcontroller (smaller number of inputs and outputs):
Arduino boards with ATMEGA328 microcontroller have operating voltages from 3.5v to 5v. They have 6 analog inputs and 14 digital input output. The clock speed is 8MHz in case of (Arduino Pro 3.3V/8MHz, Arduino Pro mini, Arduino Fio, LilyPad Arduino 328, LilyPad Arduino USB) and 16MHz in case of (Arduino Leonardo, Pro Micro 5V/16MHz, Pro Micro 3.3V/8MHz, Arduino UNO R3, Red Board etc). Their programming interface is USB via Atmega16U2 or FTDI-Compatible Header. It depends which Arduino board you are using.
Arduino boards with ATMEGA32u4 microcontroller:
If you need to introduce more functionality and sensors in your project, then you need to use a board that has more inputs and outputs. Arduino boards with ATMEGA32u4 microcontroller have more analog inputs/outputs (6 in case of LilyPad Arduino USB, Pro Micro (5v/16MHz, 3.3V/8MHz) and 12 in case of Arduino Leonardo). Similarly, maximum number of digital inputs/outputs is 20. Their Programming interface is Native USB. They also have 6 or 7 built in PWM module.
Arduino boards based on ATMEGA2560 microcontroller:
With respect to the demand of an application, more inputs and outputs pins are accommodated (54 digital and 16 analog) on this board. It has 4 UART on it since the previous two types were having only 1. Arduino Mega 2560 R3, Mega Pro 3.3V, Mega Pro 5v, Mega Pro Mini 3.3V fall in this category. They all have 14PWM module which means they can provide more control in an application design.
There is another board based on AT91Sam3X8E microcontroller called Arduino Due which has very high clock speed 84Mhz.
Now it is easy to answer which board to choose. It all depends on the application requirement. If the design is simple like designing a road signal map or simply controlling the speed or direction of a DC motor, then go for Arduino UNO. Because it is easily available in local market. Also it is cost effective, easy to understand. But your application is complex, has more controlling functions then better to use LilyPad or Arduino Leonardo.
Best Arduino Board
Arduino board is used for designing different applications. It is basically a tiny computer the helps your devices to interact with the physical environment through its input and output pins. Many projects are designed using Arduino board because it is easy to program as compared to ATMEGA or PIC microcontroller. In order to know the answer of which Arduino board is best, it is better to know first what is the purpose behind your question. For a beginner, it is always easy to start with Arduino UNO. Why? Because it is easy to start with a simple board. It has few input/output pins and only one PWM module. Second thing while selecting board is to consider the availability and its cost. Usually Arduino UNO is easily available at a very reasonable price.
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