The Arduino Breakout Board

The Arduino breakout with important labeled components is shown in Figure 1-2.

Figure 1-2. Intel Edison Arduino Breakout Board with labeled components

These important components are:

1. Female 70-pin connector. This connector mates with the male 70-pin connector on the back of the Edison compute module.

2. Buttons. These integrated buttons allow you to mechanically reset or power cycle your Intel Edison or the Arduino breakout.

3. MicroSD slot. While Intel Edison does come with 4 GB of integrated storage, the SD card slot gives the flexibility of adding additional storage to the system.

4. Barrel jack for power. This provides one option for powering your Edison. The barrel jack is the standard interface for a wall adapter power supply, which can be purchased for a few dollars on Amazon or SparkFun. Any supply between 7V and 15V with 500 mA or more will do. Alternatively, a battery with a barrel jack connector will also work, so long as it’s in the same voltage range and can supply at least 500 mA continuously.

5. External USB port. Intel Edison has one full-size USB 2.0 port, selectable via the mechanical microswitch (labeled 6 in Figure 1-2). This port can be used to connect to peripheral USB devices. If you wish to connect to multiple USB devices simultaneously, an externally powered USB hub is necessary.

6. Power mode microswitch. This switch allows you to toggle between using the full-size external USB port and the adjacent microUSB port (labeled 7 in Figure 1-2). The active port is the one that the switch is clicked toward. Note that you will need to supply external power if the USB port is selected, because the microUSB you’d otherwise use for power will be deactivated.

7. On-The-Go (OTG) microUSB port. This microUSB port supplies power and Ethernet capabilities, transfers Arduino sketches, and allows the host computer to access Edison as a mass-storage device.

8. Serial console USB port. Connecting this port to your host computer allows direct access to the Intel Edison operating system via serial communication. This port, however, does not supply power to the device.

9. Power LED indicator. When the device is powered on properly, this LED should remain in its lit state.

The Arduino breakout also has input and output, or I/O, pins that match the Arduino Uno in both physical layout and functionality. Input pins are used for signals that transmit information into your Intel Edison, such as the push of a button or measurements from a thermometer. Outputs are signals emitted by your Intel Edison, often to control attached devices. For instance, Edison might output voltage signals to make lights flicker or to display images on a screen. These I/O pins are labeled in Figure 1-3. Briefly, they are:

1. Digital input/output and pulse-width modulation

2. Analog input

3. Power

4. ICSP pins (for the Serial Peripheral Interface)

Figure 1-3. Intel Edison Arduino Breakout with pins labeled

Don’t be worried if you’re not familiar with these terms. You will be soon. In Chapter 3 and Chapter 4, you’ll learn how to use and control these specific I/O pins. And, by using electronics that have been prebuilt for this configuration, I’ll also illustrate why this layout is so extremely useful.

Other Breakout Options

Though you’ll be using the Arduino Breakout Board in this book, it is worth taking a moment to explain the difference between this and the other breakout options: the Intel Mini Breakout Board and the SparkFun Base Block, shown in Figure 1-4 and Figure 1-5, respectively.

Figure 1-4. Intel Mini Breakout Board and Intel Edison compute module

Figure 1-5. SparkFun Base Block from the top and the bottom

Both breakout boards provide access to the Edison compute module by attaching Edison to a female 70-pin connector. Both breakouts have two microUSB connectors: one for console access and one that serves as a USB On-the-Go (OTG) port. On the Intel mini breakout, the OTG port can also be used to supply power to the system. On the SparkFun Base Block, either microUSB port can be used to supply power. Both boards have LED indicators lights for Edison power and charging.

There are two additional ways to supply power to the Intel mini breakout. The pair of header pins next to the microUSBs is for supplying 7-15V power. To more easily mate with a wall plug, a barrel jack can be soldered to the pads on the underside of this portion and used in lieu of the header pins. You can also use a 7-15V battery pack with a barrel jack connector if you want a battery-powered solution. Alternatively, the pair of pins on the opposite end of the board, labeled J22, can be connected to a 3.7V lithium polymer (LiPo) battery for power. A LiPo battery will supply enough power for most of the board functionality but will not provide enough to power peripherals attached to the microUSB OTG port. The functional components of both boards are labeled in Figure 1-6 and Figure 1-7.

Figure 1-6. Parts of the Intel Mini Breakout Board: (a) 70-pin connector, (b) OTG port, (c) serial console port, (d) power LEDs, (e) 7-15V input power headers, and (f) 3.7V LiPo battery headers

Figure 1-7. Parts of the SparkFun Base Block: (a) 70-pin expansion header, (b) OTG port, (c) serial console port, (d) power LED, (e) data-transfer LEDs, and (f) power-reset button

The main difference between the two breakouts is the way they use Edison’s microcontroller. You’ll notice that the Intel mini breakout has four rows of solderable pin holes, which are routed from the 70-pin connector. This allows you to access the programmable inputs and outputs on Edison directly. The SparkFun Base Block, on the other hand, provides no access to the I/Os. So, how do you attach sensors and other devices to the Edison?

If you look at the top of the Base Block (Figure 1-5), you’ll notice that the 70-pin female connector runs through to a 70-pin male connector on the other side. SparkFun has made a series of modular boards for Edison, breaking out a few capabilities on each and designing them to stack using the 70-pin connectors all the way through. If you want access to a specific function, then you buy an additional breakout for that function and stack it with the base block. For example, if you want to read the values of a few digital inputs, you can buy the GPIO breakout. If you want to power your Edison using a LiPo battery, you can buy the battery block for stacking. And, of course, it is possible to stack more than two blocks together for increased functionality. The full list of SparkFun blocks can be found at SparkFun’s website.

Mac and Windows

Under “Step 2: Choose your Operating System,” select your OS from the dropdown menu. and click the button that appears to start the download. Alternatively, you can download the stand-alone installers directly from the software downloads page. The reason I include both is that Intel has a nasty little habit of moving its links and files around, and you’ll sometimes find broken links to downloads. The software downloads page, however, tends to be very consistent and up to date.

The standalone installer will download and install the most recent Arduino IDE, the necessary drivers (if you’re on Windows), and all other dependencies necessary for connecting to your Edison. Additionally, it will flash your Edison with the most up-to-date build.

The first time the standalone installer is run, it will download quite a heavy load, so make sure you have a strong Internet connection before running it. If you do, the whole installation and flashing process should only take 10-15 minutes. Make sure to watch the installer as it runs, because it prompts you to take certain actions, such as plugging in the Arduino board, at different times during the install process. It also helps to be watching in case the installer throws an error, which has only happened to me during the board-flashing process.

If your flash fails, you’ll either have to flash the board again with the standalone installer or perform a manual flash using the Phone Flash Tool. When run subsequent times, the installer will automatically detect the Edison-specific software on your system and skip the software download and install steps. However, in my experience with Edison, the Phone Flash Tool is much more reliable for flashing boards than the standalone installer, so it’s definitely worth trying if you run into trouble. Instructions for performing this process can be found below the installer download button on the main page, as shown in Figure 1-9.

Figure 1-9. Link location for performing a manual flash using Intel’s Phone Flash Tool

The Phone Flash Tool software, most recent Yocto complete image, and all the necessary drivers for install can also be found on the software page.

cd /media/username/Edison
rm –rf *
rm –rf .*

sudo apt-get install screen

sudo screen /dev/ttyUSB0 115200

Windows

Open the Windows Device Manager, and expand the “Ports (COM and LPT)” dropdown as shown in Figure 1-10. Look for the COM port associated with the “USB Serial Port.” In Figure 1-10, this is COM6.

Figure 1-10. Windows Device Manager for finding Edison serial communication port

To connect to Edison interactively (to send commands at the boot prompt, for example) you’ll need a terminal program. A good Windows option is PuTTY. You can download the PuTTY installer at the PuTTY download page. Look for the file named putty-0.64-installer.exe, download it, and double-click it to install after it’s finished downloading.

To access Edison, configure Putty as shown in Figure 1-11. First, select Serial for the Connection Type, and then replace COM6 with your USB Serial Port number in the Serial line text box. Set the Speed to 115200. Before opening the connection, you can save these parameters for future use by entering a name into the Saved Sessions text box and clicking the Save button as indicated in Figure 1-11. The name of your new saved session, which is “Edison” in Figure 1-11, should appear under “Default Settings.” Click the Open button in the bottom right to initiate the connection to Edison.

To connect to Edison in the future, simply open Putty and double-click the name of your saved session.

Figure 1-11. Putty configuration for connecting to Intel Edison

A blank terminal screen will appear after the connection is made. Press Enter twice, and you will be prompted for a login.

Mac

Open Terminal. If you’ve never used this program before, you can find it by searching for “terminal” in Mac Spotlight search. To connect to Edison, you’ll use a program called screen. Type the following into the terminal and then press tab:

screen /dev/tty.usbserial-

You’ll notice that the remainder of the Edison serial address autocompletes when you press tab. Complete the command by adding the configuration 115200 –L so that the entire line looks like this:

screen /dev/tty.usbserial-XXXXXXXX115200 -L

Press Enter twice, and you should see the Edison login prompt.

Linux

If you flashed your Edison using the old-fashioned method that I recommended, then you’re already screen’ed into the device. If you used the Phone Flash Tool, then you still have to connect for a first time.

To connect, open a terminal window and install screen using your distribution’s package manager. For example, under Debian and Ubuntu, you’d use the command:

sudo apt-get install screen

Now connect to Edison using screen with the following command:

sudo screen /dev/ttyUSB0 115200

Press Enter twice, and the login screen displays.

Logging In

After connecting to Edison, you will be prompted for your login. The default login on Intel Edison is “root” with no associated password. Go ahead and enter the username now, and then press Enter. Your reward will be the Linux command line:

root@edison:~#

Congratulations! You’re successfully connected to your Edison. If you’re unsure of what to do at the Linux command line, don’t worry. Chapter 2 provides a quick overview of commands to help you navigate and program your device.

Configuring Edison and Getting Online

At the Edison command prompt, type configure_edison --setup, and press Enter. Edison will walk you through the process of setting a password for the root user, naming your device, and connecting to the Internet. After connecting to the Internet, you will see the following response:

Done. Please connect your laptop or PC to the same network as this device and go to http://XXX.XXX.X.XX or http://devicename.local in your browser.

XXX.XXX.X.XX is your device IP address, and devicename is whatever you’ve just named your device. After configuration, Edison starts up its own node.js webserver, which is accessible from the browser on your host computer, so long as you’re on the same network. Open a browser window and check it out. You’ll see a webpage with the device name and IP address displayed against a blue background.

It is now possible to connect to Edison wirelessly instead of using screen, eliminating the need for a USB tether. Again, you must be on the same network in order for this to work.

To wirelessly connect from the terminal, use either of the following two commands:

ssh root@IP Address
ssh [email protected]

Then press Enter and provide your password when prompted.

If you’re using Putty on Windows, Figure 1-12 shows the setup for a wireless connection.

To terminate the wireless connection on any system, either close the window or type exit at the Edison command prompt.

Figure 1-12. Configuration for connecting wirelessly to Intel Edison using Putty; be sure to replace edison.local with your devicename.local

If you issue the command configure_edison or configure_edison --help at the Edison command prompt and hit Enter, you’ll see the other configure options that are preinstalled in the current build. You can run any of these with the command configure_edison option. Some of the more important possibilities for option are:

--wifi

Walks you through the process of configuring additional WiFi networks for Intel Edison. All networks added to Edison this way will be remembered and automatically joined at start-up, with network preference going in the order in which they were added.

--version

Returns the build version of the current Yocto system.

--latest-version

Pings Intel’s site for the newest officially released Yocto build for Edison.

--upgrade

Downloads and installs the newest officially released Yocto build for Edison. Using this option is like performing an automatic flash of the most recent build. If you’re already on the most recent build, this returns a status message and performs no action.

--flash <version>

You can use this option to flash any previous or current version of the officially released Yocto builds. Replace <version> with any version number of interest.

Note that flashing Intel Edison will remove previous configuration settings, so you’ll have to run configure_edison --setup to rename the device, set passwords, and configure WiFi each and every time you flash.

Finally, shutting down Intel Edison is easy: simply issue the following command and then press Enter:

shutdown now

Edison will display a series of shutdown messages ending with:

[  OK  ] Reached target Shutdown.

Then Edison will power itself off. The power LED on the Arduino board will turn off when the process is complete.