CHAPTER 0: Getting Started with the Raspberry Pi

CSinParallel distributes a Raspberry Pi image that enables a group of Raspberry Pis to self-organize into a compute cluster. It also works for use as a single computer to study OpenMP. It contains the code examples for this module. You can download a compressed file of this image from here. This should fit on an 8 GB or greater microSD card.

You will need to uncompress this image file and use some software like Belena etcher on a laptop or desktop computer with a card slot or adapter to write the image to the microSD card.

These instructions assume that you have a Raspberry Pi with the associated code already installed. If you are attending the CSinParallel 2020 Summer Workshop, you should have received either a Rapberry Pi Kit or a Raspberry Pi Image for use in conjunction with this workshop. We assume that you have already set up the Pi for initial use.

The following video gives an overview of the Raspberry Pi Kit and its assembly:

The following video shows how to connect to your Raspberry Pi using either SSH/PuTTY or a VNC client.

To SSH into your Pi from Mac OS X or Linux, use the following command:

ssh pi@172.27.0.254

The default password for the system is raspberry. For security purposes, it is recommended that you change this password to one that you can easily remember.

You can also connect to the Raspberry Pi directly by plugging in an HDMI-enabled monitor and USB keyboard and booting up the system.

Note

If you are using the latest Raspberry Pi 4 and want to connect to the system using an external monitor/keyboard/mouse, you will need a microHDMI cable to connect the HDMI monitor to the Pi. Older models have a full HDMI port and will not need this cable.

If you connect to the Pi by using an attached keyboard/monitor or remote desktop into it using a VNC client, booting up the Pi should yield a GUI interface to Raspbian, the Linux distro traditionally used with these machines.

For the rest of today’s workshop, you will primarily use the Terminal application and type commands into it, as if you had accessed the Pi using SSH or PuTTY. However, many students find it useful to see that the Raspberry Pi is actually a mini-computer; seeing the GUI interface really reinforces that fact.

0.1 Preliminaries: The Terminal application

If you are in a GUI environment, start the Terminal window by choosing its icon in the menu bar at the top (it looks like a black square box).

Type the following command into the Terminal window to get to the directory containing code for this tutorial:

cd CSinParallel/RaspberryPiBasics

The ls command lists the contents of the current directory (in this case RaspberryPiBasics):

ls

The ls command reveals that the RaspberryPiBasics directory contains three subdirectories:

• drugdesign

• integration

• patternlets

The rest of this writeup will lead you through some code found in above directories. These examples will let you explore how to write C code that will use the four cores available on the processor in the Raspberry Pi.

0.2 VERY useful terminal tricks

Tab completion of long names

You can complete a command without typing the whole thing by using the Tab key. For example, make sure you are still in the directory /home/pi/CSinParallel/RaspberryPiBasics by typing:

pwd

Then try listing one of the three subdirectories by starting to type the first few letters, like this, and hit Tab and see it complete the name of the directory:

ls pat[Tab]

History of commands with up and down arrow

Now that you have typed a few commands, you can get back to previous ones by hitting the up-arrow key. If you hit up-arrow more than once, you can go back down to previous commands by hitting the down-arrow key, all the way back to the prompt waiting for you to type. You can get a blank prompt at any time (even after starting to type and changing your mind) by hitting the CTRL and the u key simultaneously together (i.e. CTRL-u) .

0.3 Editor Options

Your Raspberry Pi comes equipped with many editor options. For those of you who are famliar with standard command-line editors, the Pi is equipped with vim, emacs, nano, and pico. For those readers who would like to use a command line editor, we will briefly discuss nano.

Nano

The Nano editor is extremely easy to use. To open up a file named example.c, simply type nano example.c into the command line. The available commands are located at the bottom of the Terminal window. Common commands include saving (Write Out, or CTRL-o), exiting (Exit, or CTRL-x), copying (Cut Text, or CTRL-k), pasting (Uncut Text, or CTRL-u), and Find (Where is, or CTRL-w),

Geany

For those of you who prefer a GUI editor, the Raspberry Pi comes equipped with the Geany editor. If you are using the GUI interface, you can simply go to the Programming tab at the top of your screen.

For those of you who want to use Geany but are connected to the Raspberry Pi using PuTTY/SSH, it suffices to enable X tunneling. For PuTTY, simply click “Enable X11 forwarding” under Connection -> SSH -> X11 on the left-hand side of the PuTTY application.

For those of you using SSH, simply logon to the Pi using the command ssh -X pi@172.27.0.254.

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