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electronics
As well as the usual Raspberry Pi, this is the additional equipment we used for electronics experiments. Don't worry if you don't understand what any of these mean or do, we'll explain these as we go along.
- Vilros RasberryPi Cobbler breakout
- Vilros Breadboard
- Sintron Ultimate 37 in 1 Sensor modules (for Arduino)
The first two were part of a Vilros starter kit, which also included some common electronic components, like resistors, LEDs and button switches.
Components are the individual little pieces used in electronic devices. Different kinds have different shapes or colours but they all have silver metal leads (sometimes called legs or pins)
A circuit is a combination of components put together to do a particular thing.
Electricity flows when it has a way to go around. When simple electrical components are connected to each other 'all the way round in a circle' they form a simple 'circuit'.
When you look at pictures of circuits, you might see photos of green boards with gold lines and lots of little coloured pieces attached - these are actual circuits. Or you may see black and white diagrams with lots of pictorial symbols in an interconnected framework - this is a circuit diagram which makes it clear what is connected to what.
To create permanent circuits, use a hot soldering iron to melt solder and fix components in place
https://www.youtube.com/watch?v=H3-TfdZVBCc
We don't want to solder permanent circuits, we just want to put together experiments, so we use a breadboard
Have a look at the video at: https://www.youtube.com/watch?v=oiqNaSPTI7w
To make connections easily from the breadboard to the Pi we use the Vilros Cobbler breakout module https://www.vilros.com/raspberry-pi/rasp-pi-acc/raspberry-pi-cobbler.html
see also https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/robot/breadboard/
GPIO stands for General Purpose Input Output, and is the parallel rows of pins on one long side of the Pi.
It gives the connections (sometimes called an Interface) that the Raspberry Pi uses to connect to external electronics, to read signals (input) or send them (output).
For pictures and explanations see https://www.raspberrypi.org/documentation/usage/gpio/
The pins are numbered from 1, starting at the end where the ribbon cable has a red stripe, and alternating sides: 1 & 2 are at one end, then 3 & 4, 5 & 6, etc. A 'pinout' is a list of the pin numbers, saying what each of them does - see http://pi.gadgetoid.com/pinout
These are often used as indicator lights in electronic circuits, as they are cheap and use very little power. They must be connected the right way round as the "Diode" part of the name means 'only lets electricity pass one way'.
The "Sintron Ultimate 37 in 1 Sensor Modules Kit" is sold as being for the Arduino, another popular experimental computer board. However, they are simply electronic components, so they may of course be used with the Pi, or any other electronic experiments you would like to make. To find out more see http://www.sintron-hk.com/Ultimate-37-in-1-Sensor-Modules-Kit-for-Arduino-MCU-Education-User-P3112448.aspx or to look at the list of sensors try http://www.amazon.co.uk/Sintron-Raspberry-Education-Documents-Available/dp/B00DU2IQ10#productDetails and for documentation and code (albeit arduino C programmes rather than Pi Python) download from https://www.dropbox.com/s/oitqcijo9za7j9w/37%20in%201%20sensor%20pdf%20files.zip
make sure this library is installed, from the command
sudo apt-get update sudo apt-get -y install python-rpi.gpio
sudo apt-get -y install python3-rpi.gpio
When you first install RPi.GPIO it uses something called /dev/mem, which is the name for a system memory device. Because this is an important part of your system, only the 'root' user can normally access it, using sudo.
So write your code, save it, then run it using
sudo python myprog.py
NEED TO CHECK if using one of the install methods from the project page avoids needing root - see https://pythonhosted.org/RPIO/#installation
alternatively see https://www.raspberrypi.org/forums/viewtopic.php?f=32&t=26934
You could use a gpio group which has the relevant rights - see https://www.raspberrypi.org/forums/viewtopic.php?f=32&t=7370
pigpio uses a daemon (program which is always running) to avoid needing to http://abyz.co.uk/rpi/pigpio/python.html
There is a simple to follow steps to light an LED at http://www.thirdeyevis.com/pi-page-2.php
This does not use a breadboard, but is simple to understand. If you still feel unsure, have a look at the pictures in the next project
On the other hand you might want to see something being done on a breadboard, so you could check out this simple button and led, also bi-colour led http://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/turing-machine/two.html
To recognise the components we will use, see the photos in http://www.ninjagecko.co.uk/how-to-measure-the-amount-of-light-in-a-room-using-a-light-dependent-resistor/
Gordon Drogon's projects are visually simple, and use a breadboard, but do not use the breakout and the coding is in C - https://projects.drogon.net/raspberry-pi/gpio-examples/tux-crossing/3-more-leds-and-a-button/
This project shows a circuit with more buttons and LEDs, and uses Python. It is not as clear and step-by-step, but gives useful ideas http://openmicros.org/index.php/articles/94-ciseco-product-documentation/raspberry-pi/217-getting-started-with-raspberry-pi-gpio-and-python
https://learn.adafruit.com/adafruits-raspberry-pi-lesson-11-ds18b20-temperature-sensing
- http://www.bristolwatch.com/ ** lots of different projects for different platforms - need to work through and see which are simple enough
- https://learn.adafruit.com/category/learn-raspberry-pi ** this reseller has plenty of clear and informative how-to pages to learn about putting the components they sell to good use