Friday, January 13, 2017

Arduino as a Microcontroller Reference Platform

The Arduino line of microcontrollers has, arguably, been the spark that brought programmable hardware to Makers worldwide. This article takes a look at how Arduino furthered the use of microcontrollers and how it is important defining standards today.

Arduino dates back to Hernando Barragán's design of the Wiring platform in 2004. In 2005, Massimo Banzi, with David Mellis forked the Wiring source code and started running it as a separate project. Arduino use grew through successive product releases including the Arduino Diecimila, Arduino Duemilanove, and the baseline Arduino Uno board series (in its third revision). The evolution set the Atmel ATmega328P microcontroller in the Uno to become the microcontroller standard of its time.
The Arduino Uno R3 (photo via Adafruit)
The ecosphere of Arduino, consisting of the circuit board and Arduino Integrated Development Environment (IDE) became very compelling for developers. Many software libraries were created to extend Arduino software capability and hardware connectivity. This growing capability launched the ATmega328 into many project designs. The success of the Uno board design led to other companies and makers to make Uno compatible boards based on the '328. The price of the Uno was set at the time at $35 and it did not go on sale often, requiring an investment on the purchase of each board.

In expanding the Arduino product line, the Arduino team introduced other boards based on newer microcontrollers. Some have been more widely adapted into maker designs than others. Many software libraries required changes to support different microcontroller architectures.

The development of the Atmel ATmega328P has evolved from the ATmega168 and smaller ATmega8, which all use the Atmel's AVR architecture. The '328 chip runs at a nominal 16 MHz (on the Uno) with 32 kilobytes of flash memory. This is modest by computer standards, but this chip equalled much of the industry when it was introduced.

The Arduino team, in looking for better designs, introduced the Arduino Leonardo. Leonardo was based on the Atmel ATmega32U4 microcontroller with the same 32kB of flash at 16 MHz. The chip was mostly compatible with the '328 but also had the feature of native USB controller onboard, eliminating the need for a separate USB chip on boards such as Uno. The Leonardo was less popular than the Uno but found some interesting uses due to features not found in other microcontroller boards. The native USB was very popular with other company/Maker board designers who, to this day, use the ATmega32U4 and the Leonardo software to make compelling microcontroller boards at a low cost.
Arduino Leonardo (photo via arduino.cc)
Sadly the Leonardo has been discontinued by the Arduino team but the use of the ATmega32U4 lives on in many new designs.

The Arduino Due was the Arduino team's first commercial step into the Atmel SAM architecture chips. SAM features an ARM processor, capable of speeds much higher than the Uno/Leonardo 16 MHz and also capable of more flash and other compelling features. The Due, being the first Arduino SAM board did (has) not find (found) a wide following in products or maker projects but it did (has) start software migration of the Arduino software base to use non-AVR chips. (Note: While announced as discontinued, they are still available via arduino.cc).

Note: Yes, I am skipping some Arduino releases here and there which are also AVR based designs.

The Arduino Zero, beta tested in 2014 with release in 2015, has become the new tier for microcontroller designers. Based on the newer Atmel/Microchip SAMD series, the board provides the SAM higher clock rates, ARM core, and a much smaller size.

Microchip recently bought Atmel, hence the processor provider name change.

The Zero has not supplanted the venerable Arduino Uno, yet, but the day draws closer where there are no arguments for selecting the more modern chip. Variants are smaller and much easier for manufacturers to incorporate. The Arduino Zero software is defining a new generation of compatible boards, especially from Adafruit.com which is revising a number of their microcontroller boards to use the SAMD chips. The third party boards are often less expensive than the Zero as the Zero design uses an additional debug hardware chip not used by most hobbyists.

It is conceivable that Microchip may look to discontinue AVR production through price hikes, leaving the SAMD and possibly their own PIC lines more widely available.
Arduino Zero (photo via Adafruit)
Where does the flood of Arduino compatibles leave the Arduino team?  Actually in a fairly good spot. The team are the Research and Development group foremost, providing both the low level chip firmware and the ever more powerful IDE to tap into new chips. The Arduino team continues to bring forward very compelling boards in different form factors: the Arduino Zero, MKR1000, and MKRZero boards have a great amount of capability at a cost lower than the Arduino Uno of old.

The Arduino team also has been collaborating on non-Microchip boards, including Arduino Yun, Arduino 101, and others. They also are important in expanding both the capabilities of the Arduino ecosphere and in partnering with companies other than Microchip to include Intel. The ability to easily use new, powerful microcontrollers and Linux based processors only benefits the ability of both companies and Makers to use the newer processors.

We all can look forward to the growth of the Arduino family tree, which has grown from a seedling over ten years ago. The innovation of the Arduino team has enabled people worldwide to harness some incredible hardware in making incredible products.