Microcontrollers programming Raspberry Pi
- 1. USTF COLLEGE OF ENGINEERING & INFORMATION TECHNOLOGY 210400 ENGINEERING TRAINING I (INTERNAL TRAINING) MICROCONTROLLERS ( RASPBERRY PI) A microcontroller (sometimes abbreviated µC, uC or MCU) is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Program memory in the form of NOR flash or OTP ROM is also often included on chip, as well as a typically small amount of RAM. Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications. RASPBERRYPI The Raspberry Pi is a low-cost credit-card sized single-board computer. The Raspberry Pi was created in the UK by the Raspberry Pi Foundation. The Raspberry Pi Foundation's goal is to "advance the education of adults and children, particularly in the field of computers, computer science and related subjects." Many people have used the Raspberry Pi to make things like cameras, gaming machines, robots, web servers and media centres. VERSIONS There are a few different versions of the Raspberry Pi, each made for different uses. All of the current versions use a microSD card for the operating system and file storage. They are powered by a micro-USB port, have one HDMI port, one audio/video jack socket, and a 40-pin GPIO connector. This is a list of the current versions of the Raspberry Pi and their features. • Model A+: The Model A+ is cheaper, smaller and has fewer connectors than the other versions of the Raspberry Pi. It is made for use in small, low-power projects. It features a single-core 700 MHz ARM processor, 256MBs of RAM and one USB port. • Model B+: The Model B+ is more expensive than the Model A+ and has more connectors and RAM. It features a single-core 700 MHz ARM processor, 512MBs of RAM, four USB ports and one Ethernet port. • Raspberry Pi 2, Model B: The Raspberry Pi 2 Model B is more expensive than the other versions of the Raspberry Pi and has much more RAM and a much faster processor. It features a quad-core 900MHz ARM processor, 1GB of RAM, four USB ports and one Ethernet port.
- 2. FEATURES • The Raspberry Pi uses the ARM processor architecture, which is also used by most modern mobile phones. • The Raspberry Pi can use the Linux operating system, or RISC OS, instead of Microsoft Windows or Mac OS X like most computers. • The Raspberry Pi operating system can be installed using NOOBS (recommended), or by directly installing an operating system. UNIX BASICS LISTING FILES AND DIRECTORIES ls (list) When you first login, your current working directory is your home directory. Your home directory has the same name as your user-name, for example, ee91ab, and it is where your personal files and subdirectories are saved. To find out what is in your home directory, type The ls command ( lowercase L and lowercase S ) lists the contents of your current working directory. % ls
- 3. There may be no files visible in your home directory, in which case, the UNIX prompt will be returned. Alternatively, there may already be some files inserted by the System Administrator when your account was created. ls does not, in fact, cause all the files in your home directory to be listed, but only those ones whose name does not begin with a dot (.) Files beginning with a dot (.) are known as hidden files and usually contain important program configuration information. They are hidden because you should not change them unless you are very familiar with UNIX!!! To list all files in your home directory including those whose names begin with a dot, type As you can see, ls -a lists files that are normally hidden. ls is an example of a command which can take options: -a is an example of an option. The options change the behaviour of the command. There are online manual pages that tell you which options a particular command can take, and how each option modifies the behaviour of the command. MAKING DIRECTORIES % ls -a
- 4. mkdir (make directory) We will now make a subdirectory in your home directory to hold the files you will be creating and using in the course of this tutorial. To make a subdirectory called unixstuff in your current working directory type To see the directory you have just created, type CHANGING TO A DIFFERENT DIRECTORY cd (change directory) The command cd directory means change the current working directory to 'directory'. The current working directory may be thought of as the directory you are in, i.e. your current position in the file-system tree. To change to the directory you have just made, type Type ls to see the contents (which should be empty) THE DIRECTORIES . AND .. Still in the unixstuff directory, type As you can see, in the unixstuff directory (and in all other directories), there are two special directories called (.) and (..) THE CURRENT DIRECTORY (.) In UNIX, (.) means the current directory, so typing % mkdir unixstuff % ls % cd unixstuff % ls -a
- 5. means stay where you are (the unixstuff directory). This may not seem very useful at first, but using (.) as the name of the current directory will save a lot of typing, as we shall see later in the tutorial. THE PARENT DIRECTORY (..) (..) means the parent of the current directory, so typing will take you one directory up the hierarchy (back to your home directory). Try it now. Note: typing cd with no argument always returns you to your home directory. This is very useful if you are lost in the file system. PATHNAMES pwd (print working directory) Pathnames enable you to work out where you are in relation to the whole file-system. For example, to find out the absolute pathname of your home-directory, type cd to get back to your home-directory and then type The full pathname will look something like this - which means that ee51vn (your home directory) is in the sub-directory ug1 (the group directory),which in turn is located in the its sub-directory, which is in the home sub- directory, which is in the top-level root directory called " / " . % cd . NOTE: there is a space between cd and the dot % cd .. % pwd /home/its/ug1/ee51vn
- 6. COPYING FILES cp (copy) cp file1 file2 is the command which makes a copy of file1 in the current working directory and calls it file2 What we are going to do now, is to take a file stored in an open access area of the file system, and use the cp command to copy it to your unixstuff directory. First, cd to your unixstuff directory. Then at the UNIX prompt, type, The above command means copy the file science.txt to the current directory, keeping the name the same. % cd ~/unixstuff % cp /vol/ee/ee-info/Teaching/Unix/science.txt . Note: Don't forget the dot . at the end. Remember, in UNIX, the dot means the current directory.
- 7. MOVING FILES mv (move) mv file1 file2 moves (or renames) file1 to file2 To move a file from one place to another, use the mv command. This has the effect of moving rather than copying the file, so you end up with only one file rather than two. It can also be used to rename a file, by moving the file to the same directory, but giving it a different name. We are now going to move the file science.bak to your backup directory. First, change directories to your unixstuff directory (can you remember how?). Then, inside the unixstuff directory, type Type ls and ls backups to see if it has worked. REMOVING FILES AND DIRECTORIES rm (remove), rmdir (remove directory) To delete (remove) a file, use the rm command. As an example, we are going to create a copy of the science.txt file then delete it. Inside your unixstuff directory, type (Note: The directory /vol/ee/ee-info/Teaching/Unix/ is an area to which everyone in the school has read and copy access. If you are from outside the University, you can grab a copy of the file here. Use 'File/Save As..' from the menu bar to save it into your unixstuff directory.) % mv science.bak backups/. % cp science.txt tempfile.txt % ls
- 8. You can use the rmdir command to remove a directory (make sure it is empty first). Try to remove the backups directory. You will not be able to since UNIX will not let you remove a non-empty directory. RASPBERRY PI: PYTHON SCRIPTING THE GPIO by scottkildall The GPIO: General Purpose Input/Output lets you interface your Raspberry Pi with the outside world, making it a powerful interactive device for just $40-$50. This Instructable will show you how to install the GPIO package on your Raspberry Pi and how to wire up a simple push button circuit with an LED. I use the command-line and Python for this, no web browser or GUI. Before you do this Instructable, make sure you have your Raspberry Pi ready for action. My Ultimate Raspberry Pi Configuration Guide covers how to do this in detail. You will want to have an internet connection to download the packages and probably use ssh. STEP 1: GATHER YOUR COMPONENTS % rm tempfile.txt % ls
- 10. Components * Raspberry Pi * Cobbler breakout board with cable — you can order this from Adafruit for $8. * Breadboard * Wires — breadboard or otherwise * standard LED * 270 Ohm resistor * 1K resistor * 10K resistor * Push button * USB power for RPI (not pictured) * Monitor + keyboard (not pictured) Tools * wire-stripper * small diagonal snips * multimeter for checking continuity STEP 2: ASSEMBLE YOUR CIRCUIT
- 11. We will have a simple push button that will turn an LED on when the button is pressed and off when it is released. I know, it's not super-exciting, but think of this as a building block for digital input and output. Here is the schematic and breadboard diagram. The LED is straightforward: 270 Ohm resistor is needed to light up the LED from a 3.3V input. The concept is simple: the LED is an output of pin 4 and the button is an input of pin 22. The button circuit has a pull-down resistor. Pin 22 will be pulled down to zero through the 10K resistor when the button is inactive. When it gets pressed, the 3.3V power from the Raspberry Pi goes into thepin 22 input, bypassing the 10K resistor. Without the 10K resistor, you'll have a floating input and will get erratic behavior in your code. The 1K resistor protects the Raspberry Pi from too much current. STEP 3: PUTTING IT ON THE BREADBOARD
- 12. After doing the wiring diagram in Fritzing, I laid out the components on a real breadboard. Strip the wires and use the diagonal snips for a clean-looking breadboard. This is what it looks like with the Cobbler breakout board before I attach the ribbon cable to the Pi. Even with a simple circuit like this, double-check your components to make sure you're not shorting your circuit or anything else like that. STEP 4: CONNECT TO THE PI Usethe breakout cable and connect the cobbler to your Raspberry Pi. You will want to be connected to the internet to download the latest packages via Wifi or an Ethernet cable. Power up your Raspberry Pi. STEP 5: INSTALL THE GPIO PACKAGE
- 13. The Raspberry Pi GPIO libraries may come with the latest versions of Wheezy, but maybe not. Just in case, I suggest installing them again, which involves first installing the Python Development toolkit that RPi.GPIO uses and then the GPIO package itself. Type in Then, for the GPIO libraries: If asked for confirmation on either of these, press Y You'll get the usual Linux garble like this. In my case, the Python development tools were not installed but GPIO was. STEP 6: BLINK AN LED IN PYTHON sudo apt-get install python-dev sudo apt-get install python-rpi.gpio
- 14. sudo nano gpio_blink.py sudo python gpio_blink.py At this point, I run the Raspberry Pi from my monitor with a keyboard plugged in — I usually do the package updates from ssh. On the command line, create a new python script by invoking nano. And enter in this script. The advantage with using ssh is that you can just copy-and-paste the script. Alternatively, I have this on a GitHub repository. # gpio_blink.py # by Scott Kildall (www.kildall.com) # LED is on pin 4, use a 270 Ohm resistor to ground import RPi.GPIO as GPIO import time GPIO.setwarnings(False) GPIO.setmode(GPIO.BCM) GPIO.setup(4, GPIO.OUT) state = True # endless loop, on/off for 1 second while True: GPIO.output(4,True) time.sleep(1) GPIO.output(4,False) time.sleep(1) Ctrl-X, Y to save the file. Now run the script:
- 15. Note: you have to invoke sudo — root access for the GPIO library.
- 16. sudo nano gpio_blink.py You should have a blinking LED on your circuit. We're not using the switch at all at this point. CTRL-C TO EXIT THE SCRIPT how it works - Pin 4 is an input pin. We alternate between high (True) and low (False) for 1 second at a time. - I turn warnings off because I was getting errors in my script because the GPIO wasn't properly closed (this shouldn't matter and I found it an annoyance). - Setting the mode to BCM means that the pin numbers etched on the Raspberry Cobbler match the ones that you are using in your code. STEP 7: PYTHON SCRIPT FOR SWITCH-ACTIVATED LED Now, we'll try adding a switch, using the same circuit. Type in: You can also refer to the GitHub repository, if need be. # gpio_swtich.py # by Scott Kildall (www.kildall.com) # LED is on pin 4, use a 270 Ohm reistor to ground # Switch is on pin 22, use a pull-down resistor (10K) to ground import RPi.GPIO as GPIO import time GPIO.setwarnings(False) GPIO.setmode(GPIO.BCM) GPIO.setup(4, GPIO.OUT) GPIO.setup(22,GPIO.IN) # input of the switch will change the state of the LED while True: GPIO.output(4,GPIO.input(22)) time.sleep(0.05)
- 17. CNTL-X, Y TO SAVE THE FILE
- 18. sudo python gpio_switch.py (note the indentations af Now run the script: If you press the switch, the LED should turn on and when you let it go, it should turn off. Congratulations, you have an input and output into your Raspberry Pi. how it works This is like the previous script, except that we are designating Pin 22 as an input pin. We set the output of Pin 4 to match the input of Pin 22. When Pin 22 goes high, so does Pin 4. The time.sleep(0.05) is there to account for any debouncing in the button. REFERENCES: - https://simple.wikipedia.org/wiki/Raspberry_Pi - A computer that is all on a single printed circuit board with no removable parts or external parts needed to work. - The Raspberry Pi Foundation, "About Us". Retrieved on 21 July 2015 - NOOBS stands for New Out Of Box Software. There are several choices of operating system available, including Arch Linux, OpenELEC (media center), Pidora (Fedora Linux remix), raspbmc (media center), Raspbian (recommended), and RISC OS (non-linux). - http://www.ee.surrey.ac.uk/Teaching/Unix/ http://www.instructables.com/id/Raspberry-Pi-Python-scripting-the-GPIO/
- 19. Pre-Session Home Work - DESCRIBE PIC 16F877, ARDUINO UNO, AND RASPBERRY PI 3 MODEL B IN YOUR OWN WORDS CONSIDERING THE COST, HARDWARE, AND CAPABILITIES. ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… - What is the difference between Microprocessors and Microcontrollers and is Raspberry Pi considered one of the two types or something else? ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… - What operating systems could be installed on the Raspberry Pi and what are they used for? ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ………………………………………………………………………………………………………………
- 20. Prepared by Musaab Hasan http://musaab.info - Unlike Windows OS, LINUX OS has a different directory structure as shown below. Explain what each of the directories is used for. ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… - Complete the following table according to the date of release of Raspberry Pi (0, 1, 2, 3). Raspberry Pi Version Cost RAM Size Processor Speed Bluetooth Version Wi-Fi Version Built-in Connections