Raspberry

Workshop

Ali Nik & Radi Almac

Content

 

  • What is a Raspberry?
  • Why Rasberry?
  • Generations of Raspberry
  • Parts of the raspberry
  • Operating System
  • Linux commands
  • Bash
  • GPIOs
  • Compile/Run (C,Python)
  • IoT?
  • Q & A
#!/bin/bash
Topic="Raspberry Workshop"

SubTopic[0]="What is a Raspberry"
SubTopic[1]="Why Rasberry"
SubTopic[2]="Generations of Raspberry"
SubTopic[3]="Parts of the raspberry"
SubTopic[4]="Operating System"
SubTopic[5]="SSH"
SubTopic[6]="GNU/Linux"
SubTopic[7]="Bash"
SubTopic[8]="GPIOs"
SubTopic[9]="Compile/Run (C,Python)"
SubTopic[10]="IoT?"
SubTopic[11]="Q & A"

getContent(){
    echo ${SubTopic[$1]}
}

echo $Topic
getContent $1

#Run: bash workshop.sh 0 

What is a Raspberry?

 

Is a low cost, credit-card sized computer.

 

Enables people of all ages to explore computing.

 

It’s capable of doing everything you’d expect a desktop computer to do.

 

Why Raspberry?

It’s Cheap!

It’s Tiny

Can Run A Variety Of Operating Systems

Is Really Versatile

You Can Overclock It

Generations of Raspberry

Raspberry Pi 1

Release date

February 2012

CPU

Memory

Storage

700 MHz single-core ARM1176JZF-S (model A, A+, B, B+, CM)[2]

256 MB[3] (model A, A+, B rev 1) 512 MB (model B rev 2, B+, CM)

SDHC slot (model A and B), MicroSDHC slot (model A+ and B+), 4 GB eMMC IC chip (model CM)

Raspberry Pi 1 model B+

Power

1.5 - 3.5 W

Raspberry Pi 2

Release date

February 2012

CPU

Memory

Storage

900 MHz quad-core ARM Cortex-A7

1 GB RAM

MicroSDHC slot

Raspberry Pi 2 model B

Power

4.0 W

Raspberry Pi 3

Release date

29 February 2016

CPU

Memory

Storage

1200 MHz quad-core ARM Cortex-A53

1 GB RAM

MicroSDHC slot

Raspberry Pi 3 model B

Power

4.0 W

Raspberry Pi Zero

Release date

November 2015

CPU

Memory

Storage

1000 MHz single-core ARM1176JZF-S

512 MB RAM

MicroSDHC slot

Raspberry Pi Zero

Power

Price

0.8 W

US$5

Parts of the Raspberry

GPIO Header

CSI Camera Port

Audio/Video Out

USB 2.0

Ethernet Out

HDMI Out

SD Card Slot

Micro USB Power

Broadcomm BCM2837

Status LED

DSI Display Port

Operating System

Most Popular operating systems

 

  • Raspbian
  • Ubuntu MATE
  • Snappy Ubuntu
  • Pidora
  • Linutop
  • SARPi
  • Arch Linux ARM
  • Gentoo Linux
  • FreeBSD
  • Kali Linux
  • RISC OS Pi

SSH

SSH?

Secure Shell is a cryptographic network protocol for secure data communication, remote command-line login, remote command execution, and other secure network services between two networked computers.

We will use a SSH client to connect to the Raspberry Pi remotely over a Local Area Network (LAN)

Software and configurations

No additional software is required, but we need to activate SSH service

*Putty: Free SSH and telnet client

*Xming:

pi@raspberrypi ~ $ sudo raspi-config

Restart your Pi and login again.

Advanced Options >>

SSH >>

Enable

IP Address

pi@raspberrypi ~ $ ifconfig

A list of networks will appear, look at eth0 and save the IP Address.

Using SSH in PuTTY

Password:

raspberry

User:

pi

Graphic mode?

In windows VNC  Server

pi@raspberrypi ~ $ xtightvncviewer raspberrypi.local:1

In Linux

(such as Xming)

(such as TightVncServer)

GNU/Linux 

What is GNU/Linux?

 Four main parts make up a GNU/Linux system:

 

  • The Linux kernel
  • The GNU utilities
  • A graphical desktop environment
  • Application software

Linux Kernel

The kernel is primarily responsible for four main functions:

  • System memory management
  • Software program management
  • Hardware management
  • Filesystem management

System File

Directory  Usage
/ root of the virtual directory ,where normally ,no files are placed
/bin binary directory,where many GNU user-level utilities aare stored
/boot boot directory,where boot files are stored
/div device directory,where Linux creates devices nodes
/etc system configuration files directory
/lib library directory,where system and application library files are stored
/media media directory ,a common place for mount points used for removable media
/mnt mount directory,another common place for mount points for removable media
/opt optional directory ,often used to store third-party software oackages and data file 
Directory Usage
/proc process directory ,where current hardware and process information is stored
/root root home directory
/sbin system binary directory,where many GNU admin-level utilities are stored
/run run directory,where runtime data is held during system operation
/srv service directory,where system hardware information files are stored
/tmp temporary directory
/usr user binary directory,where the bulk of GNU user-level utilities and data files are stored
/var variable directory ,for files that change frequently,such as log files
/sys system directory,where system hardware information files are stored

The Shell

  • The GNU/Linux shell is a special interactive utility.

 

  • It provides a way for users to start programs, manage files on the filesystem, and manage processes running on the Linux system.

 

  • It allows you to enter text commands, and then it interprets the commands and executes them in the kernel.

Bash

The default shell used in all Linux distributions is the bash
shell.
 The bash shell was developed by the GNU project as a replacement for the standard Unix shell, called the Bourne shell (after its creator). The bash shell name is a play on this wording, referred to as the “Bourne again shell.”

Bash

The default prompt symbol for the bash is the dollar sign ($).  

I will be using the "$ " in my codes to represent terminal input, you don't need to type it.

You can check more basic commands

Name Shortcut key Description
Cupy shift+ctrl+C Copies the selected text
Past shift+ctrl+V Pastes text
Full screen F11 Toggles on/off the terminal window filling the entire desktop
Zoom in ctrl++ Enlarges the font size in the window
Zoom out  ctrl+- Reduces the font size in the window
Normal size ctlr+0 Returns the font size to default
Find shift+ctrl+F Opens find window to provide designated text search options

Basic commands

Display current directory:

$ pwd

Now create an empty file:

Display the content of the folder:

$ touch file.txt
$ ls -lh

Display a string:

Create a variable and display its content:

$ echo "Hello world!"
Hello world!
$ var="Hello world!"
$ echo $var
Hello world!
$ echo var
var
$ rm file.zip
$ rm -R dir

Delete

More commands

Command Action 
Sudo shutdown-h now turn off your Pi
Sudo reboot Reboot your Pi
Sudo raspi-config Open configuration window
Sudo su Switch to root user
Startx Start graphic mode
cd name _of_folder Change to a specific directory
cd  .. Go back one directory
cd  / Go back to the main directory
Is Display list of files and folders

Bash

Scripts

If you need to write code that needs to run more than one time, you must consider to writing down in a file and then execute it when you need it.

Scripts needs to have at the first line the shebang.

#!/bin/bash

The shebang is used to tell the system the name of the interpreter that should be used to execute the script that follows.
 

Hello world!

    • Now time to write our first script
    • We will use an editor to write our script. 
    • Two popular editors: the traditional  vi and the user friendly  nano
    • I will use vi
    $ vi hello_world.sh

    Hello world!

      #!/bin/bash
      
      # This is a comment
      echo 'Hello World!' 
      # "" and '' have the same effect

      Type ( i) and later the code:

      Save script. (Press Esc and then :wq  Enter)

      We can execute  file type:

      $ sh hello_world.sh

      Output:

      Hello World!

      The other way to execute the file is to make it an executable file

      chmod 755 hello_world.sh
      $ ls -l hello_world
      -rwxr-xr-x 1 pi pi 63 2015-10-07 10:10 hello_world

      Execute file 

      $ ./hello_world.sh
      Hello World!

      If statment

        We can evaluate an expression: 

        #!/bin/bash
        
        x=1
        
        if [ $x -eq 10 ]; then
            echo "x is equal to 10"
        elif [ $x -gt 10]; then
            echo "x es greater than 10"
        else
            echo "x is less than 10"
        fi

        For loop

          Example 1: 

          Example 2: 

          Example 3: 

          Example 4: 

          #!/bin/bash
          
          for i in $( ls ); do
              echo item: $i
          done
          #!/bin/bash
          
          n="1 2 3 4 5 6 7 8"
          for i in $n; do
              echo "number: "$i
          done
          #!/bin/bash
          
          for i in `seq 10`; do
              echo i
          done
          #!/bin/bash
          
          for i in `seq 1 2 10`; do
              echo i
          done

          While loop

            Example 1: 

            Example 2: 

            Older UNIX shells like Borne shell  and ksh88 have clumsy, inefficient way of doing arithmetic based on external  expr  command

            #!/bin/bash
            
            count=0
            while [ $count -lt 10 ]; do
                echo $count
                count=`expr $count + 1`
            done
            #!/bin/bash
            
            count=0
            while [ $count -lt 10 ]; do
                echo $count
                count=$((count + 1))
            done

            Parameters

              You can send parameters to a script. Write:

              Execute file by typing:

              #!/bin/bash
              
              echo $0
              echo $1
              echo $2
              echo $#
              $ sh myscript.sh Hello World
              myscript.sh
              Hello
              World
              2

              Program 1

                Make a script that prints a count depending on the first parameter​

                ?

                Program 2

                  Validate if a given number is odd

                  ?

                  Program 3

                    Calculate the factorial number of a given number (0-9)

                    ?

                    GPIOs

                    General Purpose Input Output

                    About GPIOs

                    * All GPIOs are 3.3 V tolerant

                     

                    * They can provide maximum 16 mA, but not exceeding 50 mA from all at the same time


                    * 3.3 V pin can deliver 50 mA maximum


                    * 5 V pin can deliver your power supply – 700 mA for the raspberry*

                    Differences having an OS

                    Several inputs:

                    You have a mouse, keyboard, Ethernet connection, monitor, SD card without need to connect additional electronics
                    Filesystem:

                    Being able to read and write data in the Linux file system will make many projects much easier.
                    Linux tools:

                    Packaged in the Raspberry Pi’s Linux distribution is a set of core command-line utilities, which let you work with files, control processes, and automate many different tasks.
                    Languages:

                    There are many programming languages out there and embedded Linux systems like the Raspberry Pi give you the flexibility to choose whichever language you’re most comfortable with

                    Program

                    We will turn on and off and LED


                    Connect and LED to GPIO25 using a 330 ohm resistor

                    Digital Output: Lighting Up an LED

                    You can then use the Linux command line to turn the LED on and off.

                    Steps:
                    1)
                    Connect to raspberry (SSH)
                    2) In order to access the input and output pins from the command line, you’ll need to run the commands as root, the superuseraccount on the Raspberry Pi. To start running commands as root, type sudo su  at the command line and press enter:

                    The root account has administrative access to all the functions and files on the system and there is very little protecting you from damaging the operating system if you type a command that can harm it.

                    pi@raspberrypi ~ $ sudo su
                    root@raspberrypi:/home/pi#

                    Digital Output: Lighting Up an LED

                    3) Before you can use the command line to turn the LED on pin 25 on and off, you need to export the pin to the userspace(in other words, make the pin available for use outside of the confines of the Linux kernel), this way:
                     

                    root@raspberrypi:/home/pi# echo 25 > /sys/class/gpio/export

                    The echo command writes the number of the pin you want to use (25) to the export file, which is located in the folder /sys/class/gpio. When you write pin numbers to this special file, it creates a new directory in /sys/class/gpio that has the control files for the pin. In this case, it created a new directory called /sys/class/gpio/gpio25.

                    Digital Output: Lighting Up an LED

                    4) Change to that directory with the cd command and list the contents of it with ls:

                    root@raspberrypi:/home/pi# cd /sys/class/gpio/gpio25
                    root@raspberrypi:/sys/class/gpio/gpio25# ls
                    active_low direction edge power subsystem uevent value

                    The echo command writes the number of the pin you want to use (25) to the export file, which is located in the folder /sys/class/gpio. When you write pin numbers to this special file, it creates a new directory in /sys/class/gpio that has the control files for the pin. In this case, it created a new directory called /sys/class/gpio/gpio25.

                    Digital Output: Lighting Up an LED

                    5) The directionfile is how you’ll set this pin to be an input (like a button) or an output (like an LED). Since you have an LED connected to pin 25 and you want to control it, you’re going to set this pin as an output:

                    root@raspberrypi:/sys/class/gpio/gpio25# echo out > direction

                    6) To turn the LED on, you’ll use the echo command again to write the number 1 to the value file:

                    root@raspberrypi:/sys/class/gpio/gpio25# echo 1 > value

                    7) After pressing enter, the LED will turn on! Turning it off is as simple as using echo to write a zero to the value file:

                    root@raspberrypi:/sys/class/gpio/gpio25# echo 0 > value

                    Virtual Files

                    The files that you’re working with aren’t actually files on the Raspberry Pi’s SD card, but rather are a part of Linux’s virtual file system, which is a system that makes it easier to access low-level functions of the board in a simpler way.


                    For example, you could turn the LED on and off by writing to a particular section of the Raspberry Pi’s memory, but doing so would require more coding and more caution.

                    Program

                    We will read a digital input and display its status “0” for GND and “1” for 3.3v.


                    Connect the following diagram

                    Digital Input

                    Almost same instructions. Remember to run commands as root.

                    root@raspberrypi:/home/pi# echo 24 > /sys/class/gpio/export
                    root@raspberrypi:/home/pi# cd /sys/class/gpio/gpio24
                    root@raspberrypi:/sys/class/gpio/gpio24# echo in > direction
                    root@raspberrypi:/sys/class/gpio/gpio24# cat value
                    0

                    (1) Export the pin input to userspace.
                    (2) Change directory.
                    (3) Set the direction of the pin to input.
                    (4) Read the value of the of the pin using cat command.
                    (5) Print the result of the pin, zero when you aren’t not pressing the button.

                    Compile/Run (C,Python)

                    Python GPIOs

                    We can use Python to control the GPIOs.
                    Open Python by typing on the Linux console:

                    sudo python

                    First make sure this library its already installed on the Raspberry Pi. In console type:

                    >>> import RPi.GPIO as GPIO

                    If you don’t get an error, you’re all set.
                    Close the console

                    How to install Python library

                    Type the following command on the Linux console

                    $ wget http://pypi.python.org/packages/source/R/RPi.GPIO/RPi.GPIO-0.6.2.tar.gz
                    $ tar zxf RPi.GPIO-0.1.0.tar.gz
                    $ cd RPi.GPIO-0.1.0
                    $ sudo python setup.py install

                    The instructions here refer to an early version of RPi.GPIO. Please search the web for the latest version and replace the version numbers in the instructions below. On newer Raspbian distributions library is included.

                    Installing and Testing GPIO in Python

                    On the Python console type:

                    >>> import RPi.GPIO as GPIO
                    >>> GPIO.setmode(GPIO.BCM)
                    >>> GPIO.setup(25, GPIO.OUT)
                    >>> GPIO.output(25, GPIO.HIGH)
                    >>> GPIO.output(25, GPIO.LOW)
                    >>> exit()

                    1) Import GPIO library
                    2) Use BCM convention for the names of the GPIOs
                    3) Pin 25 as output
                    4) Turn on pin 25 (send 3.3v)
                    5) Turn off pin 25 (connect to ground)
                    6) Close python interpreter

                    BCM is for Broadcom BCM 2835 chip, the chip that is containned in the Raspberry Pi. When we set mode as BCM we are telling to the library that I want to use the real pin names of the BCM chip. There are other configurations that we will not use in this class (such as board).

                    Blinking an LED

                    We will use a Python Script.
                    Create a new file,  name it blink.py
                    Write the following code:

                    import RPi.GPIO as GPIO
                    import time
                    GPIO.setmode(GPIO.BCM)
                    GPIO.setup(25, GPIO.OUT)
                    while True:
                        GPIO.output(25, GPIO.HIGH)
                        time.sleep(1)
                        GPIO.output(25, GPIO.LOW)
                        time.sleep(1)	
                    touch blink.py
                    vi blink.py

                    Run:

                    pi@raspberrypi ~ $ sudo python blink.py

                    Your LED should now be blinking!!!
                    Hit Ctrl+C to stop the script and return to the command line

                    Read a Button

                    import RPi.GPIO as GPIO
                    import time
                    GPIO.setmode(GPIO.BCM)
                    GPIO.setup(18, GPIO.IN, pull_up_down=GPIO.PUD_UP)
                    count = 0
                    while True:
                        inputValue = GPIO.input(18)
                        if (inputValue == False):
                            count = count + 1
                            print("Button pressed " + str(count) + " times.")
                            time.sleep(.3)    	#Wait for the user
                        time.sleep(.01)  #So the CPU is not at 100%
                        

                    IoT?

                    What kind of things?

                    How will the things be used?

                    Amazing IoT Project

                    Open this link Now !

                    https://iotpi.localtunnel.me

                    Q & A

                    Thanks for your attention !

                    Raspberry Pi Workshop

                    By SFD2016

                    Raspberry Pi Workshop

                    Raspberry Pi Workshop - Software Freedom Day 2016 - Tehran Ali Nik & Radi Almac

                    • 390