|Exploring Edison - Meet Edison|
|Written by Harry Fairhead|
|Tuesday, 02 June 2015|
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The Intel Edison is a very attractive single board computer for IoT projects. It has WiFi and Bluetooth as standard and it's cheap. The only minor downside is the it doesn't seem quite as easy to use as an Arduino, but when you understand it a little better you'll find it is both flexible and powerful.
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The Intel Edison is remarkable because it is small, uses little power and yet has a lot of computing in a tiny SD card-sized board. It is a core component in Intel's Internet of Things (IOT) initiative where it has a large role to play.
At around $50 an Edison it isn't as cheap as an Arduino or a Raspberry Pi, but it has enough advantages over both to make it a sensible choice for many applications. Also, when you include the cost of the extras needed to provide WiFi and Bluetooth for the other two, then it is price comparable. More to the point there are situations where its small size and low power consumption make it the only sensible choice.
However, the Edison is a little different from the alternatives and you need to know a little more about its characteristics and the best ways to make use of it depending on what you are trying to achieve.
In this first chapter of Exploring Edison we take a look at the general details of the Edison in comparison to two alternatives you may already be familiar with. In looking at each device we'll consider when and why it might be an appropriate choice.
Contrast And Compare
First some basic facts - missing out a lot of fine detail:
1) Arduino Uno
The key feature of the Arduino is that it is simple but very expandable. It doesn't have a full operating system and it doesn't have a video/keyboard interface. It supports a range of digital and analog I/O as standard.
It is programmed with the help of another machine via a USB connection.Once programmed it can run standalone. If you want to use a network, WiFi or Bluetooth then you need an expansion board - a Shield - and a suitable library. The Arduino doesn't have the processing power to handle complex protocols and do something else at the same time.
2) Raspberry Pi
The Pi is a full computer that just happens to have a GPIO interface that you can use to control the real world. It has a video display and keyboard interface and you can use it standalone just like any machine - though it is common to use another PC to configure and program it via a remote console or desktop.
It is good at networking because it has Linux support for it. However, you need to buy add-on USB WiFi or Bluetooth dongles if you want to use either. It also only has digital I/O unless you buy an expansion board for Analog I/O.
3) Intel Edison
The Edison is a full computer, but without a video or keyboard interface. This means you have to work with it via a remote console - either connect via a serial/usb or network connection. Connections to the outside world can be via the built in WiFi, BlueTooth, serial port or USB. Even though it runs Linux it doesn't have a desktop environment only a command line.
It has 40 digital GPIO connections, but no analog I/O. No analog I/O might sound like a problem but for such a small form factor this isn't surprising.
All of the devices connections are made via a tiny 70-pin I/O connector. If you are used to wiring jumper wires directly to a Raspberry Pi or to an Arduino you will need to think again. The connector is intended not for direct connection but to connect to another PCB. For prototyping you need to use a breakout board and for a finished product you would create a custom board.
If you plan to use a prototype as a one off finished device then you need to keep in mind that the need for a breakout board increases the size and cost.
The Edison Architecture
You can see the general structure of the Edison in the diagram below:
You can see that the dual core 500MHz Atom processor has access to memory, WiFi, Bluetooth LE, USB and to the GPIO. You can write programs that work with all of these facilities. The Atom generally runs Yocto Linux which you can treat as a fairly standard Linux for most of the time.
In fact the structure of the Edison is little more complex than this would suggest as there is a second processor on the board - an MCU Micro
One little appreciated feature of the Edison is that it has two separate processors - the Atom Host CPU and a Quark processor acting as an MCU Microprocessor Control Unit.
The MCU is a separate small CPU that handles the interfacing with the outside world. Most of the time you can ignore it because the main Atom CPU talks to it on your behalf. The dual core Atom runs the Linux OS and the MCU is the microcontroller in the system running its own RTOS derived operating system. The MCU is a full 32 bit Intel Quark microcontroller running at 100MHz, which makes it more powerful than your average microcontroller.
Until recently the SDK didn't provide access to the MCU. Instead the host CPU was the only thing you could program and so all Edison programs accessed the GPIO via programs written on the Atom processor running Linux. Now you can also write programs for the MCU that work with the GPIO lines without the need to involve the host CPU. What this means is that you can now use the MCU to preprocess the data and allow the Host to get on with higher level tasks.
For example, a slightly contrived example would be that the MCU could be programmed to pulse a line in morse code corresponding to each letter of the alphabet. The Host processor could then simply pass the character to the MCU and expect it to get on with the task of sending the morse code.
The division of labour here is typical of the way the Host and MCU can be used together. Of course not all, indeed not many applications need this sort of division of labour and in the main you can mostly concentrate on programming the host.
So which system for which applications?
Of course these are greatly simplified design criteria and in any case there could be a requirement that makes a particular device suitable that we haven't considered.
However, the Edison is clearly a great choice if you are looking for a lot of computing power and connectivity in a low power package.
There is just one complication - the breakout board - and in particular which breakout board.
|Last Updated ( Monday, 29 June 2015 )|