RaspberryPi_Workshop and Programming with python.

Introduction to the Raspberry Pi
Jani Kalasniemi

Agenda
• FIRST STEPS
• What is a Raspberry Pi?
• Setting up your Raspberry Pi
• Using your Raspberry Pi as a Desktop
Computer
• PROGRAMMING WITH PYTHON
• Start Programming in Python
• Write your own Function
• Using GPIO to drive outputs and read inputs
• MAKINGADESKTOPAPPLICATION
• Learn about event-driven programming
• Create a simple Graphical User Interface(GUI)

• A credit-card-sized computer
• Runs on several operating systems
Raspbian WE WILLUSE RASPBIAN
Windows 10 IoT Core
RetroPie
OpenElec
• Possible to connect with a variety
of sensors to interact with the
physical world.
• Make decisions based on processing of
gathered sensor data
What is a Raspberry Pi?

Getting started with your Raspberry Pi
Basic 1-2-3
1. Connect the Raspberry Pi
to the keyboard, mouse
and the screen.
2. Plug in the power and wait
for it to boot.
3. Username : pi
Password : raspberry
(should not be needed)

Using you Raspberry Pi as a Desktop Computer
• Try to access the internet through your Raspberry Pi and find a
picture that reflects your group. Hands up when you are done, for
help if needed!
• Save this picture to the desktop.

Communicating through the terminal
• Start the terminal by going to
Accessories and then clicking
on the Terminal program.
• Run through the commands
and get a feel for how to
change directories, and list its
contents.

Programming in Python3
• General-purpose programming language used for scientific and
numerical applications as well as desktop and web applications.
• Open source language that has a lot of online resources for problems
you might come across.
• We are using Thonny IDE for programming with Python3 in our
Raspberry Pi 3 Model B
• https://stackoverflow.com is your best friend for programming
troubles

The GPIO
layout
General
Purpose
Input /
Output

Use the GPIO to drive outputs and read inputs
• Build the circuit in the figure.
Use 470 Ohm resistor
• Next we will make a program
that makes one LED blink on
and off, and the other dim up
and down in idensity when the
Button is pressed.

Use the GPIO to drive outputs and read inputs

Common errors and debugging
• Python is sensetive to intendation.
• Make sure that the variables and the functions have the same exact
writing. Watch out for small and Capital letters!
• Remember that python starts counting from zero.
i.e when using loops.

Test your program and what you have made!
Questions?

Making a sin(x) function to get some output

Should return something like this

Using a sensor with the Raspberry Pi
• The GPIO on the Raspberry Pi can only handle a maximum of 3.3V,
but many of the available sensors can return a signal of 5V to the
GPIO. This will damage the Raspberry Pi.
• How do we deal with this?
• Resistors connected as voltage dividers.
• Important to be aware of this.

MeasuringDistancewitha UltrasonicSensor:HC-SR04
• The Trigger sends a burst of
sound that bounces and hits the
Echo.
• If we measure the time it takes
from sending to receiving we can
calculate the distance.
• NOTE: Two different resistors
here

Now we need a function to calculate the distance
• With the sensor we can measure the time it takes for a signal to be
sent out and reflected back.
• We need to convert the elapsed time to distance by using the speed
of sound in air and multiplying it with the time divided by two
(Because it travels to the object, and back).

Making it loop until we tell it to stop

If the program is not giving any measurements
• Check the wiring!
• Check you code one more time.
• Check the resistors
• Check the wiring!

Introducing Tkinter :AGUI Toolkit for Python
• De facto standard GUI for Python
• Toolkit for GUI programming in Python. Not the only one, but the most
commonly used one.
• Enables you to build GUI’s with buttons, sliders, drop downs, and
other interactions for the user of the program/device you build.

Event driven programming.
• When creating a GUI you use event driven programming.
• In the GUI all buttons, sliders, etc, are known as Widgets.
• When a widget is used it make an event in you code start.

• We will create a GUI
that enables us to
turn the LED on and
off with a button in a
GUI.
• Use the 470 Ohm
resistor in the circuit.
Create a simple Graphical User Interface(GUI)

Building the code for this GUI

Building the GUI
• Now we need do decide what the GUI will actually do.
1. We will create a button that will switch the LED on and off
2. We also have to make an exit button so that when we exit the
program the LED turns off, and the GPIO port is reset to default as
input ports.

Creating the widget triggered event : ledToggle()

Creating the widget triggered event : close()

Creting the toggle button, aka a Widget

What happensif we exit the programthrough the window
exit?
This exit

Making sure that we have a clean exit

What happensif you run your program and pressa GUI
button?

Making the program run after we exit it on purpose
Will the last line be printed? If so, when?

Summary – What have we done?
• Introduced the Raspberry Pi and used it as a computer
• Learned simple commands to use in terminal
• Introduced the GPIO and how to get inputs from the physical world,
interpret them, and create output from input
• Used a XX sensor to read and evaluate data from your environment
• Introduced the Tkinter package and created a simple, event-driven,
GUI

Resources
• Raspberry Pi GPIO examples:
https://sourceforge.net/p/raspberry-gpio-python/wiki/Examples/
• Python Documentation:
https://www.python.org/doc/
• Tkinter Documentation:
https://www.tutorialspoint.com/python/python_gui_programming.htm

RaspberryPi_Workshop and Programming with python.

RaspberryPi_Workshop and Programming with python.

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