IntroductionWelcome| 00:00 |
(MUSIC).
Hi, I'm Mark Niemann-Ross, and welcome to
| | 00:06 |
up and running with Raspberry Pi.
The Raspberry Pi is a credit card-sized
| | 00:11 |
microcomputer designed by the Raspberry Pi
Foundation for experimentation and education.
| | 00:17 |
In this course, we'll explore how the
Raspberry Pi microcomputer works and get a
| | 00:23 |
taste of what it can do.
I'll start with an explanation of how to
| | 00:26 |
buy Raspberry Pi and some necessary
accessories, then show you how to
| | 00:32 |
configure and boot it up with a Linux
operating system.
| | 00:36 |
I'll show you how to talk to the Raspberry
Pi from your computer, and then explore
| | 00:40 |
how to use it with peripherals.
When you're finished with this course,
| | 00:44 |
you'll have a great platform to learn more
about embedded computers, and a working
| | 00:48 |
introduction into the world of do it
yourself computing.
| | 00:51 |
So, let's get up and running with
Raspberry Pi.
| | 00:54 |
| | Collapse this transcript |
| What you should know| 00:00 |
The Raspberry Pi is nothing but a small
computer.
| | 00:04 |
Small power needs, small physical size,
small memory.
| | 00:08 |
Everything about it is small, but it's
still just a computer.
| | 00:12 |
And it runs Linux, so you'll be more
comfortable if you know some basic commands.
| | 00:17 |
I'll discuss those commands later, but the
more you know about Linux the better off
| | 00:21 |
you'll be.
I'm also assuming you have a working
| | 00:24 |
ethernet connection with a wired, not a
wireless connection.
| | 00:28 |
You can use wireless adapters, but to get
started, it's easier with a wired connection.
| | 00:34 |
You'll also need a USB mouse, keyboard and
powered speakers.
| | 00:38 |
During this course, we'll build a simple
webcam.
| | 00:40 |
And for that you'll need an inexpensive
USB camera.
| | 00:44 |
Towards the end of this course, we'll be
discussing the general purpose input
| | 00:48 |
output pins.
Also known as GPIO.
| | 00:52 |
We're only going to have time to skim the
surface.
| | 00:54 |
GPIO requires a knowledge of electronics,
as well as some skill with a soldering iron.
| | 00:59 |
| | Collapse this transcript |
| Using the exercise files| 00:00 |
In some chapters we'll be entering code
and downloading files.
| | 00:04 |
If you're not familiar with Linux shell
programming you may find some of the
| | 00:08 |
syntax odd and prone to typographic
errors.
| | 00:11 |
Fear not, all of these scripts are
included in the exercise files and can be
| | 00:15 |
transferred to the raspberry pie for
cutting and pasting into the Raspberry Pie Editor.
| | 00:20 |
Download the exercise files from this
course at lynda.com, and unpack the zip file.
| | 00:25 |
I've already got the folder here on my
Desktop.
| | 00:28 |
You'll need to copy that fold over to a
flash drive, for use later in the course.
| | 00:32 |
I've included the source files for the
Python programs.
| | 00:36 |
I'll discuss what these programs do and
how to create them, but they are here if
| | 00:40 |
you need to refer to them during the
session.
| | 00:42 |
| | Collapse this transcript |
| Related websites and documentation| 00:00 |
The internet contains a wealth of
information about Raspberry Pi.
| | 00:04 |
As you work on more advanced topics you'll
find it helpful to know where to find answers.
| | 00:08 |
Raspberrypi.org is the official website
for the Raspberry Pi Foundation.
| | 00:13 |
It lists sources to purchase the Raspberry
Pi micro computer.
| | 00:17 |
It has a variety of tutorials and helpful
forums.
| | 00:19 |
Elinux.org is a clearing house of
information about the version of Linux
| | 00:24 |
running on Raspberry Pi.
There is information about the general
| | 00:28 |
purpose and put-out put-pins.
Raspbian Wheezy, the version of Linux
| | 00:32 |
design for the Raspberry Pi.
And sample projects.
| | 00:35 |
You'll also find information about other
embedded systems, such as the Minnow board
| | 00:40 |
and Beagle board.
Neil Black has created a stellar beginners
| | 00:44 |
guide to the Raspberry Pie, and deserves a
round of applause.
| | 00:48 |
If you ever find yourself confused during
the set up process, check here for another perspective.
| | 00:54 |
Finally, adafruit sells the Raspberry Pi
as well as power supplies, motor control
| | 00:59 |
boards, and experimentation kits.
If you can't buy parts locally, this group
| | 01:04 |
is an excellent place to purchase
accessories and other useful components.
| | 01:08 |
| | Collapse this transcript |
|
|
1. Obtaining a Raspberry Pi and AccessoriesBuying a Raspberry Pi| 00:00 |
The Raspberry Pi is made by the Raspberry
Pi Foundation in the United Kingdom.
| | 00:04 |
And unfortunately, it has a history of
being back ordered.
| | 00:08 |
Fortunately, there are several vendors you
can buy from.
| | 00:11 |
Some of them listed on the main page of
rasberrypi.org.
| | 00:15 |
You can also buy it from Amazon.com,
although you'll pay a bit more.
| | 00:19 |
Prices vary from what you'll see here.
Finally, check out adafruit.
| | 00:25 |
They are reasonably priced and also carry
some useful accessories that we'll talk
| | 00:29 |
about in a minute.
As of the date of this recording, there
| | 00:33 |
are two models of the Raspberry Pi, A and
B.
| | 00:36 |
The model A is cheaper, but only has one
USB port and no Ethernet connection.
| | 00:43 |
This may not be a problem.
If you connect a powered USB hub to the
| | 00:47 |
Model A, and then employ a USB to WI-FI
adapter, you have all the networking
| | 00:52 |
capabilities of Model B.
One main difference between the two models
| | 00:56 |
is the amount of RAM.
Model A has 256 MB of on board RAM.
| | 01:02 |
The Model B, has 512 MB.
This is not up-gradable on either model.
| | 01:10 |
All Raspberry Pi microcomputers come with
a slot for an SD memory card, an audio
| | 01:16 |
out-jack, video ports for RCA, and HDMI.
And a row of pins for general purpose
| | 01:24 |
input and output.
There are two additional connectors for
| | 01:28 |
display, and a camera, but both require
highly specialized hardware.
| | 01:33 |
Given a small price difference, typically
$10 to $25, I recommend getting the Model
| | 01:38 |
B to start with.
If you are purchasing more than one for,
| | 01:42 |
say, a classroom, the Model A may be
sufficient.
| | 01:46 |
| | Collapse this transcript |
| Selecting a monitor| 00:00 |
You'll need some way to see what the
Raspberry Pi is doing, and for that you'll
| | 00:04 |
need a monitor.
Surprisingly, there is no VGA port, only
| | 00:09 |
RCA and HDMI.
You wont be able to use a standard
| | 00:13 |
computer monitor, as they usually only
support VGA.
| | 00:16 |
Using the RCA video port is the cheapest
way to go.
| | 00:20 |
You'll need a TV with an RCA jack.
This is often used to plug in a video
| | 00:26 |
recorder or a game console.
It's quite possible that you can pick up a
| | 00:29 |
small, used TV from friends or a thrift
store.
| | 00:33 |
While you're looking for a TV also look
for an RCA connector.
| | 00:37 |
You'll often find them listed in the
stereo department as speaker cables.
| | 00:42 |
This cable will go between your Raspberry
Pi and the video input on the television.
| | 00:46 |
There is a drawback to using a television.
You may find the type difficult to read
| | 00:51 |
and the flickering may drive you crazy.
Fortunately, this is only a temporary requirement.
| | 00:57 |
Later on, I'll show you how to communicate
using VNC, which removes the need for any
| | 01:01 |
monitor, whatsoever.
There is also the option of using HDMI,
| | 01:06 |
typically found on more expensive computer
monitors and flat screen TVs.
| | 01:11 |
For our needs in this class, HDMI is
overkill and an expense you can avoid.
| | 01:16 |
If you have an HDMI monitor sitting around
the house, that's fine, but it's not
| | 01:20 |
necessary to run out and purchase one.
If you purchase an HDMI to DVI adapter
| | 01:25 |
cable, you could also use a DVI monitor.
| | 01:27 |
| | Collapse this transcript |
| Other components you'll need| 00:00 |
The designers of Raspberry Pie worked hard
to reduce costs and use standard components.
| | 00:05 |
As a result, any USB mouse or keyboard
will work just fine.
| | 00:10 |
You probably have one laying around your
house.
| | 00:13 |
Or you can pick up a used one from less
than 10 dollars.
| | 00:16 |
Power supplies are a snap.
Raspberry Pie uses a standard microUSB
| | 00:21 |
phone charger.
Check the rating on the side.
| | 00:24 |
You're looking for five volts with at
least 700 milliamps.
| | 00:28 |
You'll be happier if you purchase a power
supply branded by one of the larger phone carriers.
| | 00:34 |
If you have a model a raspberry pie, or
have plans for more USB peripherals later
| | 00:39 |
on, you'll need a USB hub.
Be sure to purchase a powered hub with its
| | 00:44 |
own power supply.
The raspberry pie doesn't supply enough
| | 00:48 |
current for devices such as hard drives or
some USB WiFi adapters.
| | 00:53 |
If you're using a powered hub plug it into
a switchable power strip along side the
| | 00:58 |
power adapter for the raspberry pie then
use that switch to turn everything on at once.
| | 01:04 |
This will avoid unexpected voltages at the
USB port.
| | 01:08 |
You'll need an SD card for external
memory.
| | 01:10 |
This will take the place of a hard drive.
SD cards are readily available from any
| | 01:16 |
electronics or camera store.
Be sure to buy a regular SD card, not a microcard.
| | 01:22 |
At a minimum, you'll need eight gigabytes.
Anything larger than 16 gigabytes will
| | 01:27 |
work, but the extra memory is unnecessary.
Don't use an SD card that has valuable
| | 01:32 |
photographs or other files.
Those photographs will all be deleted by
| | 01:36 |
the installation process.
You cannot share an SD card with your
| | 01:40 |
camera or other device.
When we get to the chapter on building a
| | 01:44 |
webcam, you'll need a USB webcam.
These are a bit more difficult to find now
| | 01:49 |
that most laptops have built in cameras.
But with some searching you'll find one.
| | 01:53 |
Almost any brand will work.
The sound jack on the Raspberry Pi is standard.
| | 01:59 |
Any standard earphone will work.
In my case, the television I'm using for a
| | 02:04 |
monitor also had an RCA audio jack.
I found a cable with an earphone plug on
| | 02:10 |
end, and an RCA connector on the other,
and now can use the volume control on a
| | 02:14 |
television to adjust the sound from the
Raspberry pie.
| | 02:17 |
| | Collapse this transcript |
|
|
2. Booting UpConnecting the hardware| 00:01 |
Now that you have all the parts you need,
connecting the Raspberry Pi is simple.
| | 00:05 |
Physically, you can't plug things in
wrong, but be careful.
| | 00:09 |
It is possible to snap connectors off of
the board if you use too much force.
| | 00:14 |
Before you plug in the power, go ahead and
connect the Ethernet cable.
| | 00:21 |
Keyboard, mouse and video.
If you wish, plug in the sound, although
| | 00:33 |
there won't be anything to hear until a
later chapter.
| | 00:37 |
Hold back on plugging in the SD card.
If you plug in power right now you'll see
| | 00:42 |
the red power LED glow, but nothing else
will happen.
| | 00:45 |
| | Collapse this transcript |
| Installing the Raspbian Wheezy operating system| 00:00 |
Your Raspberry Pi will do nothing without
an Operating System, which is loaded from
| | 00:05 |
the SD Card.
We'll be using a customized version of
| | 00:08 |
Debian Linux called Raspbian Wheezy.
This isn't the only Operating System
| | 00:13 |
available, there are also specialized OS's
that turn the Raspberry Pi into a firewall
| | 00:19 |
PBX or even an audio server.
Loading the Operating System is an easy
| | 00:24 |
process if you have internet access and
can mount an SD card on your computer.
| | 00:28 |
If you don't have access to wired
internet, you might want to consider
| | 00:32 |
purchasing a pre-formatted SD card.
Search Google for Raspbian Preinstalled SD
| | 00:38 |
card for sources.
Okay, we're ready.
| | 00:42 |
Use a web browser to download a small file
called berryboot.zip from berryterminal.com.
| | 00:50 |
Unpack the resulting zip file.
Mount your SD card on your computer,
| | 00:58 |
either using the available slot or an
adapter.
| | 01:02 |
Copy the files, not the folder, to the SD
card.
| | 01:08 |
Unmount the SD card in the normal fashion.
Just a note about SD cards, and the
| | 01:17 |
Raspberry Pie, unplug the power to the
Raspberry Pi when connecting or removing
| | 01:22 |
the SD Card.
Failing to do so might not cause any
| | 01:26 |
problems, but might also corrupt the card.
So, with the power disconnected, insert
| | 01:33 |
the SD Card into the Raspberry Pi.
Make sure the Ethernet cable is connected
| | 01:39 |
and then connect the power to the
Raspberry Pi.
| | 01:46 |
Berry boot will start up and display this
dialogue on screen.
| | 01:50 |
Adjust the green bars on the monitor so
you can see them, and select wired
| | 01:54 |
Ethernet and your location.
And then hit OK.
| | 01:58 |
Select the top disk to install the
software.
| | 02:01 |
Use No trim, discard, for the file system.
And remember, all files will be erased
| | 02:09 |
from this SD card.
If that's okay, then go ahead and hit Format.
| | 02:14 |
If that's not okay, go find a different SD
card.
| | 02:18 |
When you see the ad OS screen, choose
Debian Wheezy Raspbian.
| | 02:24 |
Those other options look fun, but save
them for later exploration.
| | 02:28 |
Once you've selected this, and hit OK, let
it run.
| | 02:31 |
BerryBoot will download the necessary
files from the internet and configure the
| | 02:37 |
SD card it could take about 15 minutes or
more depending on your internet speed.
| | 02:42 |
When it's done, exit out of BerryBoot and
Raspberry Pi will boot into Wheezy.
| | 02:47 |
Here's an interesting thing to keep in
mind.
| | 02:50 |
If you somehow mess up this SD card,
simply reformat and repeat the install process.
| | 02:56 |
You may lose a few files along the way,
but you won't physically break the card by
| | 03:01 |
deleting a necessary file.
Proceed boldly, and with no fear.
| | 03:05 |
The rasby config screen gives you a series
of options that you can use to configure
| | 03:11 |
your Raspberry Pi.
But for the most part, you can simply
| | 03:15 |
ignore them, move to finish with your
arrow keys, and hit Return.
| | 03:19 |
If you selected something you don't like
during the configuration process, you can
| | 03:29 |
restart the configuration by typing
sudurasbyconfig.
| | 03:30 |
| | Collapse this transcript |
| Testing, starting a desktop, and shutting down| 00:00 |
If the Raspberry pi was correctly figured,
you'll see a series of Linux boot messages
| | 00:05 |
scroll by followed by a request to log in.
The default user log in is pi, and the
| | 00:12 |
password is raspberry.
Now you'll be presented with a standard
| | 00:16 |
Linux prop.
Congratulations, your Raspberry pi is up
| | 00:20 |
and running...
Let's use the Linux command Clear to get a
| | 00:24 |
clear screen.
Weezy comes with a graphic user interface.
| | 00:28 |
Simply type start x, start x and you'll
see a colorful user interface complete
| | 00:38 |
with games, word processors and web
browsers.
| | 00:41 |
This is LXDE, the lightweight X11 desktop
environment.
| | 00:46 |
Spends some time exploring.
You'll find it very familiar, although a
| | 00:50 |
bit slower than your high powered desktop
computer.
| | 00:54 |
When you're done with LXDE, simply log
out.
| | 00:57 |
And you'll arrive back at the Linux
prompt.
| | 01:03 |
For the sake of the information on your SD
card, it's important to gracefully shut
| | 01:07 |
down your Raspberry pi.
Before you yank out the power cord, issue
| | 01:12 |
a shut-down command.
Sudu shutdown -h now.
| | 01:21 |
This will make sure that everything is
written to the SD card before all the
| | 01:25 |
processes are shut down.
Now you can safely pull out the power cord
| | 01:30 |
and that's the extent of the on off switch
for the Raspberry pie.
| | 01:33 |
| | Collapse this transcript |
|
|
3. Just Enough LinuxFrequently used Linux commands| 00:00 |
This is a good time to cover a few basic
Linux commands.
| | 00:04 |
We have an in depth course called Unix for
Mac OS X Users you might want to refer to.
| | 00:09 |
Don't be put off by the Mac OS X part,
Unix commands are pretty much universal
| | 00:14 |
regardless of the platform.
You'll often want to list the contents of
| | 00:18 |
a directory.
To do this in Linux, type ls, short for list.
| | 00:23 |
Predictably, Linux responds with a list of
all the files in the current directory.
| | 00:28 |
If you'd like a more detailed list, you
can also add dash al.
| | 00:32 |
So, the command looks like ls space dash
al.
| | 00:38 |
Every Linux command has a range of
options.
| | 00:40 |
You probably don't know them all by heart
since they're thousands of commands.
| | 00:45 |
Not to worry, use man to display the
manual page for each command.
| | 00:50 |
Typing man ls gives us the manual for ls,
showing us all the available options.
| | 00:58 |
Man works for every Linux command.
Many times, you'll need to switch to the
| | 01:05 |
current directory.
That command is cd.
| | 01:08 |
For example, cd space slash takes us to
the root directory.
| | 01:16 |
Simply typing cd will return you to your
home directory.
| | 01:19 |
Typing cd space dot dot will move you to
the directory just above the current directory.
| | 01:28 |
There is a tremendously handy feature in
most Linux systems called tab completion.
| | 01:34 |
This can save you time, but more
importantly, it will help you edit the
| | 01:37 |
correct file.
Here's how it works.
| | 01:40 |
Let's switch to the root directory by
typing CD slash.
| | 01:44 |
Typing ls shows us a list of the
directories and files in the current directory.
| | 01:49 |
If I wanted to switch to the home
directory, I could type cd home, or I
| | 01:53 |
could type cd then an h followed by the
Tab key.
| | 02:01 |
This tells Linux to auto complete with the
file or directory that matches with what
| | 02:05 |
I've typed.
In this case, it completes with Home.
| | 02:08 |
If I tried to switch to a nonexistent
directory, I'll know immediately that I've
| | 02:12 |
done somethings wrong.
For example I'd like to switch to the
| | 02:16 |
zebra directory.
I could type in cd zebra and get nothing.
| | 02:23 |
Or I could type in cd z followed by the
Tab key, and immediately see it doesn't exist.
| | 02:32 |
This will be particularly useful when we
are editing files.
| | 02:35 |
Issuing a command to edit a nonexistent
file normally causes that file to be
| | 02:40 |
created, which we may not want to happen.
Tab completion will prevent that.
| | 02:45 |
Clear.
Now, let's talk about sudu.
| | 02:48 |
Sudu allows us to do things we normally
shouldn't be able to do.
| | 02:53 |
So, use it cautiously.
Think of it as super user do.
| | 02:59 |
You've already seen this used once when we
shut down the Raspberry Pi.
| | 03:03 |
A normal user shouldn't be allowed to turn
off a computer, especially when more than
| | 03:06 |
one person is using it.
Shutdown dash h will generate an error.
| | 03:13 |
Only a super user should be allowed to do
that.
| | 03:16 |
So, we can first type in sudu followed by
the command we want to run as a super user.
| | 03:26 |
In the upcoming chapters, we'll need to
edit some configuration files.
| | 03:30 |
To do that, we'll use a text editor called
nano.
| | 03:33 |
I can edit files in my local directory by
entering cd to switch to my directory,
| | 03:40 |
then typing nano followed by the name of
the file I want to edit.
| | 03:44 |
We'll edit a file called yellow.
If the file doesn't exist, nano creates it.
| | 03:50 |
Make your changes, then hit Ctrl+O to
output from nano to disc and Ctrl+X to
| | 03:59 |
quit nano.
In some cases, you'll need to edit files
| | 04:04 |
located outside of your home directory.
Perhaps the etc directory.
| | 04:09 |
Trying to nano/etc/newfile and then
writing Ctrl+O, will produce an error
| | 04:15 |
message, because we don't have permission.
A simple fix is to sudu nano/etc/new file.
| | 04:30 |
Now, we're allowed to do this.
This is a new file.
| | 04:36 |
Now, I hit Ctrl+O to write to disk, and
were successful.
| | 04:40 |
Again, be careful, you don't want to sudu
delete all files.
| | 04:46 |
| | Collapse this transcript |
| Killing a process| 00:00 |
In an upcoming exercise, we'll need to
start a program and then stop it.
| | 00:04 |
In Linux, programs that are currently
active are known as processes.
| | 00:09 |
You can show a list of all the active
processes by typing psux.
| | 00:14 |
There's a wealth of information about each
process.
| | 00:17 |
We're mainly interested in the process ID
or PID.
| | 00:21 |
If you're looking for the process id of a
certain command, use ps dash capital c
| | 00:26 |
followed by the command.
For example, ps -C k helper tells us the
| | 00:35 |
process id for khelper is 8.
Once you know a processes' ID you can stop
| | 00:40 |
that process.
Be careful with this, killing the wrong
| | 00:44 |
process can be a bad thing.
I'm going to start a background process we
| | 00:48 |
can safely kill.
Let's call up a manual page for the LS command.
| | 00:51 |
Enter man, ls, followed by an ampershand.
To tell it to run in the background.
| | 00:57 |
Use ps ux to identify the PID for our new
command.
| | 01:03 |
Here the PID is 2102, now kill -9 2102 and
that will kill the process.
| | 01:13 |
The -9 is just a simple way of saying, yes
I really do mean to do this, ps will
| | 01:20 |
confirm that the man process is no longer
running.
| | 01:24 |
We can also kill a process by name.
Let's restart man ls epershand, use ps ux
| | 01:32 |
to see the process, and here it is.
Now, use pkill -9 man, ps ux shows us that
| | 01:43 |
the process is gone.
Again, be careful when killing processes.
| | 01:47 |
If you kill something important, you may
have to reboot.
| | 01:51 |
| | Collapse this transcript |
|
|
4. Setting Up VNCWhy VNC is useful| 00:00 |
VNC is the acronym for Virtual Network
Computing.
| | 00:04 |
It allows you to control one computer from
another over a network.
| | 00:08 |
It provides a graphical user interface,
including the mouse and keyboard.
| | 00:13 |
In our case, it will allow us to see and
use the Raspberry Pi GUI without the need
| | 00:19 |
for a physical keyboard.
Right now, this is a convenience, and if
| | 00:22 |
you're happy with your current mouse,
keyboard and monitor setup, you can skip
| | 00:26 |
this chapter.
When you begin experimenting with devices
| | 00:29 |
that require one or more USB ports, VNC
will become a necessity.
| | 00:34 |
There are four steps to setting up VNC.
Setting up a static IP address, installing
| | 00:41 |
VNC on the Raspberry Pi, setting up to
start at boot, and then connecting to VNC
| | 00:48 |
with a client.
| | 00:48 |
| | Collapse this transcript |
| Setting up a static IP address| 00:00 |
Connecting with the Raspberry Pie over VNC
requires a static IP address one that
| | 00:06 |
doesn't change.
IP addresses look like 192.168.0.102, and
| | 00:15 |
every computer accessing the internet gets
one.
| | 00:18 |
Usually they are provided for a temporary
period of time called dynamic.
| | 00:23 |
If you have a system administrator, ask
them for a static IP address and the
| | 00:27 |
gateway address.
They may ask you for a MAC address.
| | 00:31 |
I'll show you how to get that in just a
minute.
| | 00:34 |
If you are on a home network you'll need
to discover a usable I P address.
| | 00:39 |
To do this, turn to your Raspberry Pi and
type I F config.
| | 00:46 |
One of the entries will be labeled with
ETH0.
| | 00:49 |
Look for a line that starts with inetaddr.
This is the IP address currently being
| | 00:56 |
used by the Raspberry Pi.
Write that number down.
| | 00:59 |
We're mainly interested in the first three
sets of numbers, in this case192.168.0.
| | 01:09 |
Replace the last number with 50 and write
that down.
| | 01:13 |
If your system administrator asks for the
Mac address of your Raspberry Pie, look
| | 01:18 |
for HWADR followed by letters and numbers
punctuated by colons.
| | 01:24 |
In this case, my Mac address is
b8:27:eb:af:60:31.
| | 01:36 |
I'm going to clear the screen, you'll also
need to know your gateway address.
| | 01:41 |
If you didn't get this from your system
administrator or our on home network,
| | 01:46 |
simply type netstat - r.
A table is displayed, one column is
| | 01:54 |
labeled gateway.
The first row is default and displays an
| | 01:58 |
IP address for the gateway.
In this case, my gateway address is
| | 02:02 |
192.168.0.1 write that down.
Setting up a static IP should really be
| | 02:05 |
done at the router controlling your
network.
| | 02:09 |
If you have a system administrator, they
will do this for you.
| | 02:15 |
If you have a home computer you may be
able to get away with being a little bit
| | 02:19 |
sloppy and not reserving the address.
However, if you start receiving error
| | 02:24 |
messages about 'this IP Address is already
in use by another computer'.
| | 02:28 |
Change the 50 to a larger number or refer
to the documentation for your router for
| | 02:33 |
instructions on how to reserve an IP
address.
| | 02:36 |
If you do reserve an IP address at your
router, go ahead and reboot your Raspberry
| | 02:41 |
Pi right now.
Now that you have a static IP address,
| | 02:45 |
you'll need to set the raspberry pi to use
it.
| | 02:48 |
From a command line prompt, enter
sudunano/etc/network/interifaces.
| | 03:04 |
Remember that Sudu allows us to execute
commands as a super user.
| | 03:09 |
Nano is a text editor and interfaces is a
network configuration file.
| | 03:16 |
Your screen will display the contents of
the interfaces config file.
| | 03:20 |
Look for the line with iface eth0 inet
dhcp.
| | 03:24 |
Then use the cursor keys and Delete key to
remove it.
| | 03:30 |
Use the cursor keys to move to the bottom
of the screen.
| | 03:34 |
You'll need to add some text, here are the
new lines: iface eth0 inet static.
| | 03:45 |
address And then enter the static IP
address you obtained from i f config.
| | 03:52 |
In my case it's 192.168.0.50.
Now enter net mask space 255.255.255.0
| | 04:11 |
then, gateway.
And then enter the gateway number you
| | 04:16 |
obtained from NetStand in my case,
192.168.0.1.
| | 04:22 |
When you're satisfied, type Ctrl + O to
output the file from nano to disk, and
| | 04:32 |
then type Ctrl +X to quit nano.
Reboot the Raspberry Pie to implement
| | 04:36 |
these changes, use sudo_shut down_r for
reboot now.
| | 04:47 |
| | Collapse this transcript |
| Installing VNC on a Raspberry Pi| 00:00 |
Now that you have a static address, you
can install a VNC server on Raspberry pie.
| | 00:05 |
If you're using Rasbia-weezy /g, this is
simple.
| | 00:09 |
At a command prompt enter pseudo apt-get
for apt-get, space, install, tight VNC
| | 00:20 |
server, that's T I G H T V N C, S E R, V E
R...
| | 00:27 |
You'll be asked, Do you want to continue?
Yes or No?.
| | 00:31 |
Answer with a capital Y and take a break.
When the install is finished, enter VNCSERVER.
| | 00:39 |
You'll be asked to create a password, I
use raspberry.
| | 00:47 |
It notes that the password is longer than
eight characters, go ahead and retype raspberry.
| | 00:55 |
Next you'll be asked, would you like to
enter a view only password?
| | 00:58 |
Enter N for no.
And congratulations.
| | 01:02 |
You're running VNC on your Raspberry pi.
| | 01:06 |
| | Collapse this transcript |
| Using the Macintosh VNC client to connect| 00:00 |
Before going any further, let's check to
make sure everything is working correctly.
| | 00:05 |
To do this, you'll need a VNC client.
If you're using a Macintosh with a recent
| | 00:10 |
version of OS 10, this is simple.
Go to the finder, then.
| | 00:16 |
Go from the top menu and down to Connect
to Server.
| | 00:19 |
Enter vnc:// and the IP address you have
given to your Raspberry Pie.
| | 00:27 |
In my case, 192.168.0.50 followed by a
colon.
| | 00:36 |
And the number 5901.
5901 is the number of the port the
| | 00:41 |
Raspberry Pi VNC server is listening to.
Hit Connect.
| | 00:47 |
And don't worry about the screen sharing
encryption, hit Connect again.
| | 00:53 |
Now type in the password you created
earlier, raspberry.
| | 00:58 |
If everything is working correctly, you'll
see a large raspberry.
| | 01:03 |
Congratulations.
| | 01:04 |
| | Collapse this transcript |
| Using the Chrome VNC client to connect| 00:00 |
If you're not on a Macintosh computer,
you'll need to download a VNC client.
| | 00:04 |
You can obtain free viewers from
realvnc.com.
| | 00:09 |
There are clients for Windows, IOS,
Android and the Chrome browser.
| | 00:13 |
Yes, you can control your Raspberry Pie
from your cell phone.
| | 00:18 |
In case you're not working on a
Mackintosh, let's step through the Chrome browser.
| | 00:22 |
You can use Chrome on any platform,
Windows or Macintosh, which makes it
| | 00:28 |
pretty convenient.
It may be a bit slower than using an
| | 00:32 |
application, but the Raspberry Pie is
moving pretty slow anyway, so performance
| | 00:37 |
really doesn't matter.
Installing VNC into a Chrome browser is simple.
| | 00:42 |
I'll assume you've already installed the
Chrome browser on your computer.
| | 00:45 |
If not, use your existing browser to
search the Internet for Google Chrome.
| | 00:51 |
The first entry will be a link to the
download, follow the instructions from there.
| | 00:54 |
To install the VNC extensions, start
Chrome just like normal.
| | 00:58 |
Go to Window, Extensions, and then get
more extensions to browse the gallery.
| | 01:06 |
This takes you to the Chrome web store.
Search for VNC and choose the VNC Viewer
| | 01:13 |
from RealVNC.
If you're not signed in, you'll need to do
| | 01:18 |
so now.
Click on ADD TO CHROME.
| | 01:24 |
Click Add, to accept the warning, and
after a minute, you'll find the VNC Viewer
| | 01:29 |
has been installed.
Any time you open up a new tab, you'll see
| | 01:32 |
the VNC Viewer icon.
Click to start VNC, enter the Static IP
| | 01:38 |
Address for the Raspberry Pi, in this
case, 192.168.0.50:5901 and hit return.
| | 01:50 |
Go ahead and hit Connect.
And type in your password, raspberry and
| | 01:59 |
hit Presto.
You're connected to the Raspberry Pie.
| | 02:01 |
| | Collapse this transcript |
| Running VNC at boot| 00:00 |
As you become more advanced you may not
always need VNC, but for now let's assume
| | 00:06 |
you want VNC to run every time you start
your Raspberry pi.
| | 00:10 |
This involves installing a start up file
which we can do from the VNC client.
| | 00:15 |
We'll need a file from the exercise files
that are on the flash drive you created earlier.
| | 00:20 |
Insert the flash drive in a USB port on
the Raspberry pi.
| | 00:24 |
In my case, I had to unplug the mouse to
open a port.
| | 00:28 |
In the lower left corner is a startup
menu.
| | 00:30 |
Go to Accessories, then File Manager.
Look for the flash drive you've just
| | 00:36 |
inserted and copy the exercise files to
the Pi directory.
| | 00:40 |
You'll need super-user access to copy the
VNC server file to the proper location.
| | 00:46 |
Open LX Terminal and cd to the home
directory.
| | 00:49 |
Then use sudo to copy the files to the
init.d directory.
| | 00:55 |
Sudo, copy, exercise files using tab
completion.
| | 00:59 |
Tight vncserver/etc/init.d.
Now we need to tell the system to use this
| | 01:10 |
file at startup.
Enter sudo update-rc.d tightvnc server default.
| | 01:22 |
And you can ignore the INS serve warnings.
Restart your Raspberry Pi using sudo shut
| | 01:34 |
down dash r now.
Now every time you start your Raspberry
| | 01:38 |
Pi, VNC will be available.
If you ever want to shut off the VNC
| | 01:43 |
server, use sudo update-rc.d
tightvncserver remove.
| | 01:52 |
| | Collapse this transcript |
|
|
5. Working with SoundIntroducing sound on the Raspberry Pi| 00:00 |
The Raspberry Pi can produce high-quality
streaming sound, but not out of the box.
| | 00:06 |
You'll need to install extra software and
jiggle a few controls.
| | 00:09 |
In this movie, we'll go over the basics of
setting up sound and making sure it works.
| | 00:14 |
Sound can come from the HDMI ports, or the
3.5 millimeter audio jack.
| | 00:20 |
The audio jack is the simplest, so let's
start there.
| | 00:23 |
If you're going to use speakers be sure to
they're powered and have an amplifier, as
| | 00:27 |
the Raspberry Pi only puts out two watts
and won't be very audible.
| | 00:31 |
Let's run a quick check to make sure
everything is connected correctly.
| | 00:35 |
At a command line prompt type,
speaker-test.
| | 00:40 |
The Raspberry Pie will play white noise
through the speaker.
| | 00:45 |
You should be able to hear static, press
Ctrl+C to stop the test.
| | 00:50 |
If you didn't hear any sound, check to
make sure the plug is firmly seated in the jack.
| | 00:55 |
Sometimes, it doesn't get pushed in all
the way.
| | 00:58 |
Check your speakers with a different sound
source, just to make sure they're working.
| | 01:03 |
In some cases HDMI monitors will stop
sound.
| | 01:07 |
A solution is to simply unplug the HDMI
monitor and rely on VNC connection.
| | 01:12 |
If that's not the problem we can check the
Raspberry Pi mixer.
| | 01:15 |
At a command prompt alsamixer, alsamixer.
You'll see a thermometer showing the
| | 01:23 |
volume level.
Use the arrow keys to increase or decrease
| | 01:27 |
the volume.
Hit Escape to exit.
| | 01:32 |
Raspberry Pi comes with a simple sound
playing command called Aplay.
| | 01:36 |
Here's a quick demonstration.
Change to the User Share Sounds alsa
| | 01:42 |
directory, cd /usr/share/sounds/alsa, and
then list the contents.
| | 01:54 |
You'll see a list of available sound
files.
| | 01:58 |
To play a sound simply type aplay, and the
name of a wav file.
| | 02:02 |
In this case, Front Center.
>> Center.
| | 02:10 |
>> If you're feeling adventurous, you can
use Linux to find and play all sounds on
| | 02:14 |
the system CD to your home directory.
Then type in find/, to start at the top of
| | 02:20 |
the directory, dash name, star, .wav to
find all wav files.
| | 02:28 |
And then dash exec aplay with some curly
braces a backslash and a semi-colon, (MUSIC).
| | 02:47 |
>> This will play an amusing series of
sounds until you type Ctrl+C.
| | 02:52 |
Some sounds may not play, aplay is
somewhat finicky about what files it will perform.
| | 02:57 |
There are other more robust sound
utilities available.
| | 03:00 |
Search online for raspberrypie.mpg
| | 03:05 |
| | Collapse this transcript |
| Playing a sound with Python| 00:00 |
The Raspberry Pi comes with several
programming languages installed and ready
| | 00:04 |
for use.
You'll find C, Bash, Lua, Scratch, Squeak,
| | 00:09 |
and two versions of Python.
If you're familiar with Linux, you'll be
| | 00:13 |
right at home.
But, even if you've never seen Linux
| | 00:15 |
before today, it's easy to get started.
I'm going to build on our recent
| | 00:19 |
discussion about using sound on Raspberry
Pi with a programming example in Python 3.
| | 00:25 |
Let's write a program that plays a sound
for each day of the week if at any time
| | 00:29 |
you get confused or need help I've
included the finished program as part of
| | 00:33 |
the exercise files.
To launch a Python development environment
| | 00:37 |
double click on the desktop icon labelled
IDEL 3 don't use this plain IDEL that's
| | 00:43 |
for Python 2.7 and we want to use Python
3.
| | 00:47 |
If you can't see the icon, look in the
start up menu under programming.
| | 00:54 |
It will take a minute, but the Raspberry
Pie will launch idle.
| | 00:57 |
The standard integrated development
environment for Python.
| | 01:01 |
It defaults to a shell that allows
experimentation with Python, so let's try
| | 01:05 |
something simple.
At the triple arrow prompt type in
| | 01:08 |
Datetime dot now parentheses.
You'll see an error message telling us
| | 01:15 |
that datetime isn't defined.
That's easy to fix.
| | 01:19 |
Type from datetime import Date time, now
repeat our last command datetime dot now parentheses.
| | 01:31 |
And Python will print today's date and
time.
| | 01:34 |
Now let's write a program, if you're not
familiar wit Python you may want to brush
| | 01:39 |
up with Python three Essential Training
here on Lynda dot com.
| | 01:43 |
Let me open up the exercise file and
explain how it works.
| | 01:47 |
Use file open, navigate to the home pie
exercise files and open Pythons sales dot py.
| | 01:58 |
The first thing we do in our program is
import the os library and then from the
| | 02:03 |
date time library we import a function
called date time Throughout the program,
| | 02:08 |
there are several debug functions that may
be useful.
| | 02:11 |
An easy way to turn them on and off is to
include a debug variable.
| | 02:14 |
i'm going to set it to false for now.
If you need to debug the function, you can
| | 02:20 |
change this to true.
Next, define a function that will be used
| | 02:24 |
to play the sound and show diagnostic
information.
| | 02:27 |
death play a sound in parenthesis end
colon.
| | 02:31 |
And let's add a couple of lines for
debugging.
| | 02:33 |
If debug equals true, colon, then print,
n, comma, end, the dash.
| | 02:40 |
And then print day sounds, bracket, end
bracket, parentheses.
| | 02:45 |
Be careful with parentheses and brackets.
And that's the end of the debugging block.
| | 02:50 |
Move out by one indent level to show the
end of the code block.
| | 02:53 |
In Python Three the easiest way to play a
sound is to use the system level command A
| | 02:58 |
Play to pass a complete system command as
a string.
| | 03:03 |
So let's create that string.
Today sound, equals, quote A Play, space,
| | 03:10 |
plus, say day directory plus DaySounds
bracket n bracket plus quote .wav space
| | 03:18 |
dash R 1 quote.
Then you send it to the system, os.system
| | 03:24 |
parentheses todaySound parentheses.
Now we need a variable that points to the
| | 03:29 |
directory holding the sound files.
We've provided a set of sound files in the
| | 03:34 |
exercise files for your use.
Earlier, I showed you how to use tab
| | 03:38 |
completion to build a path, and it works
in idle as well.
| | 03:42 |
(UNKNOWN) directoy equals
"/home/pie/exercise files, and don't
| | 03:50 |
forget to use a back slash in front of the
space between exercise and files.
| | 03:56 |
Then slash day of week sounds slash quote.
Day sounds is an array of the names of
| | 04:02 |
wave files to be played for each day of
the week.
| | 04:06 |
In the exercise files we've used
understandable names.
| | 04:09 |
Day sounds equals bracket quote Monday,
start with Monday.
| | 04:13 |
In a minute we'll ask the raspberry pie
for the day of the week and it will return
| | 04:18 |
an integer where zero equals Monday One
equals Tuesday and so on.
| | 04:22 |
In Python the first element of an array is
indexed to zero.
| | 04:27 |
So that's where we put Monday.
Then put in the rest of the names of the week.
| | 04:31 |
Now we have two lines of code to retrieve
the day of the week.
| | 04:34 |
Today's date equalls datetime.now
parenthesees.
| | 04:39 |
And today's day equals
datetime.weekday(today's date).
| | 04:43 |
Playing todays sound is done by passing
the day of the week index to the play a
| | 04:51 |
sound function.
Play a sound(today's date.) Finally a bit
| | 04:56 |
more debug code.
This will go through the array of sounds
| | 05:00 |
and make sure they are all playable.
If DEBUG == True; then print "Other sounds
| | 05:06 |
are..." and then a for, for n in range
(0,7): playASound(n).
| | 05:16 |
To run your program, use Run > Run Module,
the Python Shell will come to the front
| | 05:26 |
and play your program.
>> Wednesday.
| | 05:28 |
>> If there are errors, they will appear
along with details on where to find the problem.
| | 05:34 |
Remember, the complete program is also
located in the exercise files.
| | 05:38 |
If you get confused check your program
against my original.
| | 05:41 |
| | Collapse this transcript |
|
|
6. Building a Webcam Website with PythonIntroduction to a webcam project| 00:00 |
In this project, we'll step through the
process of using the Raspberry Pi for a
| | 00:04 |
very simple webcam.
This project will combine several skills
| | 00:08 |
to help you understand how to use the
Raspberry Pi for projects.
| | 00:12 |
And will give you a jumping off point for
projects of your own.
| | 00:16 |
| | Collapse this transcript |
| Obtaining and installing a webcam| 00:00 |
You'll need to obtain a USB webcam.
These used to be very easy to obtain but
| | 00:05 |
now that cameras are built into every
laptop, they're becoming rare.
| | 00:09 |
I found mine at a thrift store.
But you can also purchase them online if
| | 00:14 |
they aren't available at a local
electronics store.
| | 00:19 |
Pretty much any webcam will work, but if
you're unsure, consult the list at elinux.org.
| | 00:24 |
Just make sure it has a full size USB
connector, and note that some webcams
| | 00:30 |
require a powered USB hub.
Installation is easy.
| | 00:34 |
Just plug it in to the USB connector.
| | 00:37 |
| | Collapse this transcript |
| Using fswebcam to drive the camera| 00:00 |
The Raspberry Pi doesn't come with
software for a webcam.
| | 00:04 |
Fortunately it's easy to install, we can
use apt-get to install fswebcam.
| | 00:11 |
Here's how, sudo apt-get install fswebcam.
This will show some activity.
| | 00:21 |
There's nothing for you to do except just
watch.
| | 00:24 |
When it finishes, cd will take you to your
home directory.
| | 00:29 |
Now, with the webcam plugged in, type
fswebcam test.jpg.
| | 00:37 |
Smile, the webcam should take your
picture.
| | 00:41 |
You can take a look at the picture by
opening the file manager.
| | 00:49 |
Click on pi, then open up the Image
Viewer, there I am.
| | 00:54 |
How flattering.
If your image is chopped up it may be
| | 00:59 |
taking a minute for your webcam to
respond.
| | 01:01 |
You can tell fswebcam to delete the first
two images by typing fswebcam --skip 2
| | 01:12 |
test.jpg, and that will skip the first two
frames.
| | 01:20 |
You can also tell fswebcam to take a
series of pictures, fswebcam --loop 2, a
| | 01:29 |
number of seconds, and then background to
run in the backrgound and we'll tell it to
| | 01:37 |
skip the first image.
And save the result to test.jpg.
| | 01:45 |
| | Collapse this transcript |
| Using Python as a web server| 00:00 |
Now that the webcam is capturing an image,
let's set up a web server, so that we can
| | 00:05 |
see the image on a different computer.
There are lots of web servers available
| | 00:09 |
for the raspberry pi, but the easiest is
the web server built into the Python
| | 00:14 |
programming language.
And already available on your raspberry pi.
| | 00:18 |
To start a web server simply enter python3
-m http.server 8000.
| | 00:30 |
That's all, were running this in a
foreground so Ctrl+C, will stop it.
| | 00:36 |
While the web server is running, you can
test it by going to another computer on
| | 00:41 |
your local network and entering http://.
Followed by the static IP address you
| | 00:47 |
created earlier.
In my case, 192.168.0.50 followed by colon 8000.
| | 00:56 |
8000 is the port the web server is
listening to.
| | 01:00 |
You'll see a very simple home page.
If you'd like to see the image you've
| | 01:04 |
captured with a web cam.
Either click on test.jpeg or follow the
| | 01:10 |
8000 with slash test.jpeg, I've provided a
simple HTML file you can use as a homepage.
| | 01:19 |
It's located in the exercise files and is
called index.html.
| | 01:24 |
It simply shows the test image, and then
refreshes the page every second.
| | 01:34 |
To copy this to your home directory,
simply drag it on top of the pi icon.
| | 01:40 |
When you point a browser at the raspberry
pi, that updated image is now sent to the browser.
| | 01:45 |
| | Collapse this transcript |
| Starting the webcam at boot| 00:00 |
Starting up the webcam server at boot
requires starting FS webcam and the Python
| | 00:06 |
Web Server with a script.
This is done the same as when we installed
| | 00:09 |
VNC to run at boot.
First, you'll need a script to turn the
| | 00:13 |
camera and the web server on.
I've provided a script in exercise files
| | 00:17 |
that will do this, all you need to do is
install it.
| | 00:20 |
You'll need super user access to do so.
Let's start by cding to our directory and
| | 00:26 |
then, sudo, copy, exercise, use tab
completion to fill out the name of the file.
| | 00:34 |
And I'm looking for a file called, py
webcam serve.
| | 00:37 |
If I type in py Nothing happens.
That's because there's probably more than
| | 00:42 |
one file that starts with py.
To get a list of those, I can hit Tab twice.
| | 00:48 |
And that gives me a list of all of the
files in that directory that start with py.
| | 00:52 |
I can see the pyWebCamServe has a capital
w.
| | 00:56 |
Now if I hit Tab I see it completes it
with pyWebCamServe.
| | 00:59 |
I complete the rest of the line with
/etc/init.d.
| | 01:05 |
Now I need to tell the system to use this
file at start up.
| | 01:08 |
Sudo update - rc.d piewebcamserve
defaults.
| | 01:20 |
You can ignore the INS serve warnings.
Now reboot.
| | 01:24 |
Sudo shutdown dash r now.
There are lots of things you could do to
| | 01:33 |
improve this project the rest is up to you
and your creativity.
| | 01:37 |
| | Collapse this transcript |
|
|
7. Using GPIOWhat is GPIO?| 00:00 |
The Raspberry pi has a set of pins for
general purpose input/output or GPIO for short.
| | 00:07 |
It's right here on the board.
A double row of 13 pins for 26 pins in all.
| | 00:13 |
Using these pins, you can control external
devices like motors or lights and receive
| | 00:18 |
signals from switches or sensors.
Hooking devices up to the Raspberry Pi
| | 00:23 |
requires a knowledge of electronics.
You'll need to know a bit about resistors,
| | 00:28 |
transistors, possibly how to solder.
And what a short circuit is and how to
| | 00:32 |
avoid it.
But it's all worth it, because hooking the
| | 00:35 |
Raspberry Pi up to another device is where
the fun truly starts.
| | 00:39 |
Unfortunately, we don't have enough time
in this course to walk step by step
| | 00:43 |
through construction of a project.
But I can give you a couple of pointers
| | 00:48 |
that will start you on your way.
As an example, I'm going to animate this
| | 00:52 |
rubber fish.
It's perfect.
| | 00:54 |
It comes with simple servo motors a built
in speaker a battery compartment and it's amusing.
| | 01:00 |
| | Collapse this transcript |
| Creating interface circuits| 00:00 |
The first thing you should be aware of is
that the GPIO isn't buffered, that is to
| | 00:05 |
say, be careful.
If you hook up something wrong you may
| | 00:08 |
short it out.
A loud snap, a quick puff of smoke and
| | 00:11 |
you'll be buying a new Raspberry Pi.
So, when you're starting out, look online
| | 00:16 |
for circuit diagrams and followed them
closely.
| | 00:20 |
In general, unless you're buffering the
IO, do not connect the Raspberry Pi GPIO
| | 00:26 |
to anything that puts out voltage or pulls
current.
| | 00:28 |
An alternative to building your own
circuit board is to buy a pre-assembled
| | 00:34 |
buffer board.
You'll find a long list of them at elinux.org.
| | 00:40 |
If you don't have electronics experience,
this is your only choice, but it's a good choice.
| | 00:45 |
The rubber fish comes with three simple
servo motors.
| | 00:49 |
Applying outage to a motor moves it out.
Turning off voltage allows the spring to
| | 00:54 |
return to a resting position.
The motors pulls about four watts a
| | 00:58 |
current, which is more than the Raspberry
pie can provide.
| | 01:01 |
So, I set up a simple transistor circuit,
and tested the connection.
| | 01:07 |
Connecting the interface to the correct
GPIO pins, requires a bit of study.
| | 01:14 |
Some pins provide power.
Some provide input or output depending on
| | 01:19 |
how they're configured.
Some are simply ground.
| | 01:24 |
And the physical pins don't correspond to
the GPIO numbers.
| | 01:28 |
For example, the seventh bottom pin is
noted as GPIO 27 unless you're using a
| | 01:36 |
revision one board board in, which case it
is GPIO 21.
| | 01:40 |
Don't worry if that doesn't make any sense
at first.
| | 01:43 |
It's confusing for everyone.
Again figuring out GPIO pin out are a bit
| | 01:47 |
beyond this course.
It will require some knowledge of electronics.
| | 01:52 |
Familiarity with a volt O meter and some
soldering skills.
| | 01:56 |
This is just a walk through, so you
understand how they work.
| | 01:59 |
| | Collapse this transcript |
| Controlling a device with GPIO in Python| 00:00 |
Once the hardware is all correctly
connected, we can write a program to
| | 00:04 |
control or read those pins.
Let's walk through a Python program that
| | 00:08 |
will control the rubber fish.
The complete program is located in the
| | 00:12 |
exercise files and you can open it up
using the Python Idol editor, located on
| | 00:16 |
your Raspberry Pi desktop.
First, we need a module that will allow us
| | 00:20 |
to communicate with a GPIO ports.
Python has one called rpi.gpio.
| | 00:25 |
If you're using raspbian wheezy, this
module is already installed, and you can
| | 00:31 |
simply import it.
The first line does that, import rpi.gpio
| | 00:37 |
as GPIO.
I'm also going to use a sleep timer so I
| | 00:41 |
grab that from the time module.
From time import sleep.
| | 00:45 |
I need to tell the GPIO module that I'm
going to refer to the actual pin number
| | 00:49 |
instead of the designated signal number.
GPIO.setmode uses GPIO.BOARD to indicate that.
| | 00:58 |
This means I can simply count pins on the
raspberry pie to figure out what to connect.
| | 01:02 |
This doesn't mean I can just choose any
pin.
| | 01:05 |
Some pins are always 3.3 volts, some are
ground and some are used to provide 5
| | 01:12 |
volts to the raspberry pie.
In my case, I'm going to connect to GPIO 18.
| | 01:18 |
Which is present on physical pin 12, which
is the sixth pin from the left on the
| | 01:24 |
bottom row, and yes this is confusing.
Don't just guess, you'll most likely guess
| | 01:30 |
wrong and fry your Raspberry pi.
Pins can be configured to either read a
| | 01:35 |
signal, say from a switch, or write a
signal...
| | 01:39 |
The following line sets up pin 11 to
accept input.
| | 01:42 |
GPIO.setup(11, GPIO.IN).
Then to tell the Raspberry pi to send a
| | 01:51 |
signal out of pin 12, just simply use
GPIO.setup(12, GPIO.OUT).
| | 02:00 |
Now, all that remains is to set a pin high
or low.
| | 02:04 |
Setting it high will set the voltage of
the pin to 3.3 volts, setting it low will
| | 02:09 |
set the pin to 0 volts.
I've put this in a loop so it will turn
| | 02:13 |
the pin on, pause, then off, pause, then
on.
| | 02:18 |
So I've set it up while true colon sleeper
time equals 3, which will control the
| | 02:23 |
amount of pause between the commands.
And then GPIO dot output to pin 12, set it
| | 02:29 |
low with GPIO.LOW.
Pause three seconds, GPIO dot output,
| | 02:34 |
parentheses 12, and then you set the pin
to high with GPIO.HIGH.
| | 02:39 |
And then sleep for another three seconds.
Accepting input is equally as simple.
| | 02:44 |
You just simply read the value from the
pin.
| | 02:47 |
In this case, I'm setting the variable
input_value equal to the state of
| | 02:51 |
GPIO.input number 11.
Save the program, then run it using sudo.
| | 02:58 |
sudo python3 tryGPIO.
Any time you use the GPIO pins you have to
| | 03:07 |
do so as the super user.
This example is in Python but there are a
| | 03:13 |
wide range of other languages you can use
with the Raspberry Pi.
| | 03:19 |
Including C, Bash, Lua, Scratch, and two
versions of Python.
| | 03:25 |
Plus more that can be installed from the
internet.
| | 03:27 |
You'll find a growing list at elinux.org.
| | 03:31 |
| | Collapse this transcript |
|
|
ConclusionWhere to go from here?| 00:00 |
Now that you have a functioning Raspberry
Pi and an understanding of how it works,
| | 00:04 |
the rest is up to you and your ingenuity.
Join the community on Facebook, follow the
| | 00:09 |
blog at Raspberrypi.org and above all,
experiment.
| | 00:13 |
I appreciate your time, and I hope your
enjoyed watching this course as much as I
| | 00:17 |
enjoyed making it.
Please take a moment to provide feedback
| | 00:20 |
through the course homepage on lynda.com.
Thank you.
| | 00:25 |
| | Collapse this transcript |
|
|
