Write the value from state (LOW) to ledPin. For instance, the button was pressed or it wasn't, never anything in between. Development platforms like the BeagleBone provide an environment for a wonderful hybrid of both software and hardware hacking. There's no password set by default, so if it prompts you, just hit enter. Back in the early days of the Web, every page you visited was represented by a HTML file on the web server. BeagleBone spans that divide. Type "help", "copyright", "credits" or "license" for more information. Hopefully you don't expect them to fire up a terminal and edit the BeagleBone's crontab file. In most cases, this is where you'll put projects that you work on as the root user. 2. As you start to create your own projects with BeagleBone, a good foundation in Linux will be incredibly helpful. The first time you connect, your SSH client may warn you that the host is unknown. This can be RISING (low to high), FALLING (high to low), or CHANGE (any state change). Because JavaScript is an entirely different language than Python, keep an eye on the differences in syntax. Create a variable called level to store the PWM duty cycle and start it at 0.0. After connecting the monitor to your BeagleBone and rebooting the board, you should see the desktop environment on screen ). Many times, the inspiration for my projects comes from what other people are making and what technology they're using. Enter vnc:// beaglebone.local:5900 (see -11) and click connect. When it senses that the door has gone from being closed to being opened, it saves a time value into alertTime. For every subsequent check, if the door is still opened, it checks if 60 seconds has passed. Still, it's probably best to make sure you're plugging only 5 volts into the board. In addition to an Internet-connected BeagleBone, you'll need the following to prototype this project: TMP35 analog temperature sensor (This component is available from vendors like Digi-Key or Mouser. 3. Print a greeting message to the console with the value of name. Connect a 10K pull-down resistor between pin 11 on header P8 and ground. In this chapter, I'll show you a few ways to make an elegant interface to Internet-connected projects. Give your device a name and choose whether you want the data to be public or private. Any version will work in this project because we can use code to check for either a high or low signal. It also indicates that we're logged in as a superuser. Now you can see all the directories explained in -1 (plus a few others). Run the changeLevel function (defined next). Since it can only take up to 1.8 volts, using the other voltage pins will permanently damage your board. As it stands, Example 6-11 will only run when you execute it from the command line and it will stop when you terminate it, when you log out, or when you reboot the BeagleBone. For the tutorials in this chapter, I've provided a quick reference to a few of the pins in -4, but in case you want to use any of the other pins on the board, here's how to derive the number you'll need: You may have noticed that we've only labeled a few pins in -4 and here's why: many pins can be assigned different functions, not just digital input and output. 4. Edit the ntpdate configuration file with nano: root@beaglebone:/usr/share/zoneinfo/America# nano /etc/default/ntpdate Update the line with NTPSERVERS="" so that it looks like this: NTPSERVERS="pool.ntp.org" pool.ntp.org will redirect your to one of about 4,000 public Network Time Protocol servers. With a framework like Node.js, JavaScript can act as the engine of a web server, which affords web application developers many of the advantages of the event-driven nature of the language. Next, you're going to create some files and directories, so let's go back into the root account's home directory: root@beaglebone:/# cd /home/root root@beaglebone:~#. On the menu bar at the top of the screen, click ApplicationsSystem ToolsTerminal, which will bring up a windowed terminal. This is one of the seven analog input pins. It's a good idea to compartmentalize the different parts of your project and be able to test them individually before connecting them all together. Define a function called printValue that takes an input which will be referred to as x within the function. Even though embedded Linux development boards are becoming easier to work with, it does take some skill (or at least patience and persistence) to use them if you're just starting out. To terminate the server and get back to the command line, type Control-C. It can then serve the data via their web interface or via an API for your own applications. If fadingUp is false, subtract .01 from level. You'll need to find the details of your mail provider's SMTP server, which is what you connect to in order to send email. To share with me directly, you can send me an email at mattr@make zine.com or you can find me on Twitter with the handle @MattRichardson. That number stored in value is then rounded to two decimal places to make it look better when it's printed to the console. The name of the function to execute when a state change is detected. If you choose to power your board through this port, the processing speed will be reduced to decrease its power consumption. If set as true, it will always execute the callback function when a state change is detected. As root, you'll have unfettered access to most of the system's functions. We can then set the pin low and turn off the LED by writing a 0 to the value file: root@beaglebone:/sys/class/gpio/gpio44# echo 0 > value If you saw the LED illuminate after writing 1 to its value file and it turned off when you wrote 0 to the value file, congratulations! I encourage you to contact me with any feedback as you read this book. When you click the Run button at the top of the Cloud9 editor, you'll see the LED USR3 blinking on the board and if you hooked up an LED to pin 13 on header P8, you should also see that flash in sync with the on-board LED. If you're using Windows, you'll need to download a VNC client application such as RealVNC or TightVNC. If you just want to reboot the board, use the reboot command. 3. beaglebone This indicates the hostname. Gerald has certainly never been one to be satisfied with typical notions of what is good enough. Much of the Linux software that's already out there can be run on the BeagleBone. 2. It will give you just enough of the basics in a few different realms so that you can start digging deeper on your own. There are a few steps involved in setting the mode of a GPIO pin and therefore a few lines of code. Take note of the auto-generated API key, the Feed ID, and your channel's name on the device's page. *:5a"-{6 k^ evV`fB8+>!.emVg1uI&icDkm;K"[,,aVYYh;GN<6ghrcww4llhQ9x_qVDY*5fN_?=`+aoD_fk(.!weI|^}Re}iI-e?f.57. The part of the Bea-gleBone that's responsible for this is called the analog-to-digital converter, or ADC. You don't need to worry about it for now, but in case you're wondering, files that appear on the desktop in the graphical user interface are stored there. ", "Garage door is open!") When it shows you the prompt "login as:" type root and press enter. Selling or distributing a CD-ROM of examples from MAKE books does require permission. After you log in again, you should see your custom hostname in the prompt. Many projects in MAKE Magazine start off as Make: Projects! Be very careful not to accidentally connect the rail to the 5 volt source on pins 5 and 6. You could write the code yourself to send this formatting along with the return statement in that example, but including all that code in the Python script would get unwieldy very quickly. Be sure to review Set the duty cycle of ledPin to 5%. The tilde is shorthand for the logged in user's home directory. For more information about MAKE, visit us online: To comment or ask technical questions about this book, send email to: If you're familiar with Linux, you probably think of it firstly as a computer operating system, like OS X or Windows. You can also find me on Twitter with the name @MattRichardson. Using another strand of hookup wire, connect pin 2 from the Power-Switch Tail to one of the ground pins on the BeagleBone. By default, LED 0 will show a "heartbeat" when the system is running. Here are a few additional resources for using Python online: This is a popular library helps you build HTTP requests and process their responses. Within the function, that input will be referred to as x. Create an object called msg and store the body in it in the MIME format (the body is passed as an input to this function). In the preceding example, you typed out the path to change the working directory to the root account's home directory, but there are a couple shortcuts that can take you there much more quickly. To be sure, we can always execute pwd again: Because the tilde is shorthand for your home directory, you'll only see it when you're in your home directory or in one of its subdirectories. Putting Python Projects Online 71 -Set the value of alertTime to the current time plus 60 seconds. endobj Source code for button.py Set up pin 11 on header P8 to be used as an input. In Example 6-2 we hardcoded the SMTP server, login, email address, and password into the alertMe function, which means we put these details directly into the code as opposed to taking them as inputs from other sources. I'll also point to outside resources for learning more about Python if you're interested in digging a little deeper into the language. We can test this function by itself, before getting into working on the physical side of the project. Save the file by typing Control-O and exit nano with Control-X. You can specify if you want the code to be executed when the pin is rising (it goes from low to high), falling (it goes from high to low), or both. After you've got it working, remove the test line alertMe("Alert! Using a jumper wire, connect the negative rail of the breadboard to one of the BeagleBone's ground pins, which are located on pin one and two of header P8 and P9. 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