The original Arduino was designed for one specific task, and it fit that task perfectly. With the success of the original Arduino board, the company decided to create more designs, some of them for very specifi c tasks. Also, because the original Arduino design was open source, several companies and individuals have developed their own Arduino-compatible boards, or have followed in the open source tradition, and have proposed their modifications to Arduino. Arduino has begun a certification program to ensure compatibility with boards that use different processors, with the Intel Galileo being the first to receive such a certification. Anyone is free to make their own Arduino-based derivative, but the name and logo of Arduino are trademarked. As such, you’ll find a number of boards with names ending in “uino”, implying compatibility.
Arduino made the board design open source, but it still produces its own boards. These boards are known as official boards. Other companies also make Arduino-compatible boards.
Arduino Uno
The Arduino Uno is the “standard” Arduino board and the most readily available. It is powered by an Atmel ATmega328, with a total of 32 KB of flash memory, 2 KB of SRAM, and 1 KB of EEPROM memory. With a total of 14 digital I/O pins and 6 analog I/O pins, this is a very capable device, able to run most programs. An on-board ATmega16u2 chip manages serial communication. It is one of the least expensive boards and the most used. When starting a new project, if you do not know what Arduino to use, start with the Uno, as shown in Figure 1-3.
Arduino Leonardo
The Arduino Leonardo is slightly different to the Uno. Based on the ATmega32u4, this microcontroller has enhanced USB capabilities and therefore does not require a dedicated microchip for USB serial communication like the Uno. One advantage to this is cost; one less microchip means a cheaper solution. It also means that a developer can use the microcontroller as a native USB device, increasing flexibility in the communication with a computer. The Leonardo can effectively emulate a keyboard and mouse via USB HID, as shown in Figure 1-4.
Arduino Ethernet
The Arduino Ethernet, based on the ATmega328 found in the Uno, can connect to an Ethernet network, a functionality needed in a number of projects. Physically, the Arduino Ethernet has the same 14-digital inputs/outputs as the Arduino Uno, with the exception that 4 are used to control the Ethernet module and onboard micro-SD card reader, limiting the amount of pins available.
It is interesting to note that the Arduino Ethernet has an optional POE module, short for Power Over Ethernet. This option enables the Arduino Ethernet to be powered directly from an Ethernet connection, without the need for an external power source provided that there is a POE supply on the other end of the Ethernet cable. Without POE, the Arduino must be powered by an external source Another difference from other Arduino boards is the lack of a USB connector. Because most of the space is taken up with an Ethernet connector, this device instead supports a 6-pin serial programming header and is compatible with numerous programming devices (including a device from Arduino, the USBSerial adapter). The Arduino Ethernet is shown in Figure 1-5.
Arduino Mega 2560
The Arduino Mega 2560 is only slightly larger than the Arduino Uno, but it has more input and output pins. It has a total of 54 digital I/O pins and 16 analog inputs. It also has a large amount of flash memory: 256 KB, capable of storing larger programs than the Uno. It also has generous SRAM and EEPROM: 8 KB and 4 KB, respectively. It also has 4 hardware UART ports, making it an ideal platform for communicating with multiple devices serially.
Arduino Mega boards are used when large amount of inputs and outputs are required. It is shown in Figure 1-6.
Arduino Mini
The Arduino Mini is a tiny device, useful for applications where space is reduced to the absolute minimum (see Figure 1-7). It has 14 digital I/O pins and 4 analog input pins. (Four more are available but are not broken out.) The device has the strict minimum: it does not have a USB connector; it has no power regulator; and it has no headers. Programming is done via an external USB or RS232 to TTL serial adapter. It is shown in Figure 1-7.
Arduino Micro
The Arduino Micro lives up to its name; it is one of the smallest Arduino boards available. Despite its small size, it still has a large amount of input and output pins; it has 20 digital input/output pins, of which 7 can be used as PWM outputs. It also has 12 analog inputs. The Micro is not designed to have shields but it does have an interesting layout, as shown in Figure 1-8. It can be placed directly onto a breadboard.
Arduino Due
The Arduino Due differs from all other Arduino designs in that it is not based on an AVR, but rather uses a microcontroller based on an ARM Cortex-M3, the Atmel SAM3X8E. This advanced microcontroller is clocked at 84 MHz and is a full 32-bit device. It has a large amount of digital and analog I/O: 54 digital pins (12 of which can be used as PWM) and 12 analog inputs. The board has 4 UARTs, an SPI header, a Twin-Wire Interface, and even includes a JTAG header.
The Arduino Due has more strict power supply requirements, and the microcontroller itself is powered under 3.3 V. Be careful not to apply 5 V to any of the pins: otherwise, you will damage the board. When choosing a shield for the Due, make sure the shield supports 3.3 V. You can identify if a shield is Due compatible by making sure it conforms to the Arduino R3 layout.
The Arduino Due is an incredibly powerful Arduino. The Due has 512 KB of flash memory and a total of 96 KB of SRAM. It can handle the largest programs at a fast speed. If you have a lot of calculations to perform, this is the Arduino that you need (Figure 1-9).
LilyPad Arduino
The LilyPad Arduino is an interesting device. It strays from the typical Arduino build because it is not rectangular, but round. Secondly, it does not support shields. What it is designed for, however, is to be a small device that is perfect for wearable computing, or e-fabric. The round shape means that connectors are evenly distributed, and its small scale (2 inches in diameter) makes it perfect or wearable devices. This device is easily hidden, and multiple manufacturers have designed devices especially for the LilyPad: Wearable LEDs, light sensors, even battery supply boxes that can be sewn into fabric.
Arduino Pro
The Arduino Pro exists in two versions, based either on the ATmega168 or the ATmega328. The 168 version operates at 3.3 V with an 8 MHz clock, and the 328 version runs on 5 V at 16 MHz. Both versions have 14 digital inputs/outputs and 6 analog inputs. It has a JST battery power connector, a power switch to select between power modes, and space reserved for a power jack, if needed. It does not have a USB connector but instead uses a FTDI cable for programming.
The Arduino Pro is different from most other Arduinos in that while it is a prototyping board it is designed to be embedded in projects. It does not come with headers—indeed, it does not have any headers at all, as shown in Figure 1-11. All the digital and analog inputs and outputs are placed at the exterior of the board, retaining shield layout, ready to be soldered to wire or connectors if necessary. Instead of being used for prototyping, the Arduino Pro is aimed at semipermanent installation in finished products. The Arduino Pro was not designed by Arduino but was designed and is manufactured by SparkFun Electronics.
Arduino Robot
The Arduino Robot is, simply put, an Arduino on wheels. There are two Arduino boards on the Robot—one controls the on-board motors, and the other contains sensors. The Control board controls the Motor board and gives it instructions on how to operate. The Control board is powered by an ATmega32u4, with 32 KB of flash, 2.5 KB of SRAM, and 1 KB of EEPROM. It also has an external I2C EEPROM device, providing more storage. It has a compass, a speaker, three LEDs, a five-button key pad, and an LCD screen. It also has three solder points for external I2C devices. It also has I/O capability, with five digital I/Os, six PWMs, and four analog inputs. There is space for eight analog inputs (for distance sensors, ultrasound sensors, or other sensors) and six digital I/O pins for other devices (four of which can be used for analog input).
The Motor board is a fully independent board, powered by an ATmega32u4, the same microcontroller as on the Control board. The Motor board contains two wheels powered independently, five IR sensors, and I2C and SPI ports. It also contains the power supply; it is powered by four rechargeable AA batteries, and contains a jack port to recharge the on-board batteries. The board can also be powered by an on-board USB connector, but in this configuration, for safety reasons, the motors are disabled (Figure 1-12).
Arduino Esplora
The Arduino Esplora is a strange device. Where most Arduinos are designed to sit on a table or be placed under fabric, the Esplora is designed to be held in your hand. Based on an ATmega32u4, it is not shield compatible and does not have any solder points for inputs and outputs. Instead, it looks and feels like a game pad; it has thumb inputs in the form of four digital switches, one analog joystick, and a linear potentiometer. For more feedback, the Esplora has a buzzer and an RGB LED. It also features more advanced devices; it has an on-board microphone, a temperature sensor, a connector for an LCD screen, and a three-axis accelerometer.
The Esplora has 32 KB of flash; 4 KB are used by the bootloader. It has 2.5 KB of SRAM, and 1 KB of EEPROM. It is a capable device, and it makes up for its lack of connectors with four TinkerKit connectors: two inputs and two outputs, as shown in Figure 1-13.
Arduino Yún
The Arduino Yún is based on an ATmega32u4, but it also has an Atheros AR9331 on the same board. The Atheros processor has a complete Linux distribution, based on OpenWRT, famous for Linux-based wireless routers.
The Arduino Yún has built-in Ethernet and WiFi, and also has a micro-SD slot. The Yún is different from other Arduinos and shields in that it has advanced network functionality; the Arduino can send commands to OpenWRT and then continue processing its sketch (Figure 1-14). The two processors work independently, the Bridge library facilitates communication between the two processors.
Arduino Tre
The not-yet-released Arduino Tre promises to be a phenomenal beast. Up until now, the fastest Arduino was the Arduino Due, based on an ARM-compatible microcontroller. The Tre, created by Arduino and BeagleBoard, combines the power of a full computer with the flexible input and output of an Arduino.
The Tre has a Cortex-A8 class processor, the Sitara AM335X processor, running at 1 GHz. This processor has access to 512 MB of RAM and has an HDMI port capable of displaying Full HD (1920 x 1080). All this power is interfaced by an Atmel ATmega32u4 using the Arduino programming environment that enthusiasts have come to love.
Arduino Zero
The Arduino Zero is a brand new Arduino using Atmel’s SAM D21 microcontroller. It has 256 KB of flash memory, 32 KB of RAM, and runs at 48 MHz. The Arduino Zero is designed to handle future requirements from the Maker community, by creating a design that is powerful, robust, and flexible enough to be used in robotics and wearable projects, as well as the IoT. It is also the first design to have an advanced debugger interface.
Your Own Arduino?
Arduino has always created open-source designs, and all the boards listed previously have schematic files available directly from the Arduino website, under a Creative Commons Attribution Share-Alike license. Put simply, this means that you are free to study the Arduino schematics to make your own or
to make modifications either for personal use or professional use on the condition that you give credit to Arduino for the original design and release your own design under the same license.
to make modifications either for personal use or professional use on the condition that you give credit to Arduino for the original design and release your own design under the same license.
With the exception of the Arduino Due, all Arduino boards are based on the Atmel AVR. These chips can be bought from electronic distributors with the Arduino firmware pre-installed, or if you have the proper tools, you can buy blank chips and load the firmware yourself.
