Arduino Sketches. Langbridge James A.

learning platforms existed: Parallax's BASIC Stamp and PIC devices were in use, but Atmel's AVR made its appearance and added another alternative for electronics enthusiasts. Previously, on digital systems, the logic was defined before creating the board. Inputs and outputs were connected to logic gates, and the functionality was designed into the product. Now, with the AVR series, enthusiasts and engineers had a new possibility. Instead of designing functionality electronically, systems could be designed to interact with the outside world using computer programming. This simplified electronics; instead of using multiple logic gates, everything was connected directly to the microcontroller, which could then be programmed to react to events from the outside world. Programs could be flashed and re-flashed, and devices could be programmed and re-programmed, opening the gates to a whole new world of electronics. In theory, a device could be made that would adapt to almost every situation possible. The technology existed; all that was left was for someone to create the device.

      The Arduino Project

      The Arduino project started in 2005, and was a project for the students at the Interaction Design Institute Ivrea in Ivrea, Italy. Students were taught to use a BASIC Stamp, a small microcontroller device programmable in PBASIC (a variation of the BASIC programming language), but the price for this device (almost $75) was considered to be too expensive for students, not only on acquisition, but also to replace damaged units.

      Arduino started as a project for design students, targeted as a replacement for the BASIC Stamp. The Atmel 8-bit AVR was chosen for its simplicity and low price, and had the extra advantage of requiring few external components. It also has an impressive amount of inputs and outputs, making it a perfect choice for future designs.

      Students and teachers worked together on a new design, one that used the Atmel AVR and that could easily accept external cards. When the original design was completed, researchers worked to make the design lighter, less expensive and easily usable by students, enthusiasts, and engineers. The first Arduino board was born. Improvements on the Arduino's original design, such as replacing the DB-9 serial connector with USB, has helped expand the platform's appeal.

      There are two sides to every Arduino. There is, of course, the hardware, but this is only part of an Arduino project. Every Atmel microcontroller used for Arduino comes with a specific firmware, a small program embedded on every device that looks for a program to run or helps install a program using a serial device.

      The final design was released as open source and was designed and sold by Arduino. Releasing Arduino as an Open Source Hardware project was an interesting move. Because it was open source, it attracted more and more users to look into their projects. Because the Arduino already had an excellent input/output design, users began to create boards that could be added to the original Arduino. When Arduino designed a new board, it kept the original input/output layout, enabling existing add-ons to be used with new designs.

      Originally designed for education, the Arduino project became famous with electronics enthusiasts, and its boards were sold by more and more distributors.

      Arduino not only created the hardware – an embedded device that does not have corresponding software and support programs might still be difficult to use – but also spent a lot of time developing its own language and Integrated Development Environment (IDE). The end result is a nice IDE that can work on Windows, MacOS, and Linux and converts the Arduino language (a high level variant of C/C++) to AVR code. The Arduino development environment hides away all the complications linked to embedded systems and mixing software – such as setting up an environment, linkers, pesky command lines – and lets the developer program using simple C language functions through the Arduino Programming Language.

      The ATmega Series

      Atmel has placed its AVR design into different groups, depending on various factors. There are numerous AVR microcontrollers, and knowing which one to use is essential for projects. Some ATmega devices have more memory, or more digital and analog inputs and outputs, or have a specific package size.

      The ATmega Series

      The Atmel megaAVR is the muscle of the AVR series. They are designed for applications requiring large amounts of code, with flash memory ranging from 4 k all the way to 512 k, enough for the most demanding of programs. Atmel megaAVR devices come in various sizes, ranging from 28 pins all the way to 100 pins. These devices have an impressive amount of embedded systems: analog to digital converters, multiple serial modes, and watchdog timers, to name but a few. They also have a large amount of digital input and output lines, making them ideal for devices that communicate with numerous components.

      There are close to 100 ATmega devices, ranging in flash memory size and package size, and some models have advanced features such as internal LCD Controllers, CAN controllers, USB controllers, and Lightning controllers. ATmega chips are found in almost every Arduino board produced.

      You can find more information on the ATmega series on Atmel's website at: http://www.atmel.com/products/microcontrollers/avr/megaavr.aspx.

      The ATtiny Series

      The Atmel tinyAVR series has small-package devices designed for applications that require performance and power efficiency. These devices live up to their name “tiny”; the smallest tinyAVR is 1.5 mm by 1.4 mm. The word “tiny” is only a reference to their size. Their power is comparable to the larger AVRs; they have multiple I/O pins that can be easily configured and a Universal Serial Interface that can be configured as SPI, UART, or TWI. They can also be powered with as little as 0.7 V, making them highly energy-efficient. They can be used in single-chip solutions or in glue logic and distributed intelligence in larger systems.

      There are more than 30 ATtiny devices, and they come with between 0.5 k and 16 k of flash memory, and range from 6-pin packages to 32-pin packages. You can find more information on the ATtiny series on Atmel's website at: http://www.atmel.com/products/microcontrollers/avr/tinyavr.aspx.

      While the ATtiny series are powerful devices given their size, no Arduino uses this device as its microcontroller.

      Other Series

      Atmel also has different AVR series: The XMEGA series deliver real-time performance, with added encryption using AES and DES modules, and includes an interesting technology, the XMEGA Custom Logic, reducing the need for external electronics.

      Atmel also produces a 32-bit version of its AVR microcontroller: the UC3. Supporting fixed-point DSP, a DMA controller, Atmel's famous Peripheral Event System and advanced power management, the UC3 is a formidable microcontroller. You can find more information on Atmel's AVR website at: http://www.atmel.com/products/microcontrollers/avr/default.aspx.

      The Different Arduinos

      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 specific 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.

      WARNING

      Beware of counterfeits! Some companies propose Arduino boards that are cheaper than the original Arduino series, but these boards tend to have less reliable hardware. Arduino boards are cheap but still use good quality electronic components, whereas counterfeit boards may well use components that will not last as long. Paying a few extra dollars for a board helps Arduino finance more research to create new Arduino boards and software,