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Raspberry Pi Introduction 🥧

Quick Overview

You can use a Raspberry Pi (RPi for short) basically like any other desktop computer. The first time you boot the RPi, you will need to install an OS, which is all explained pretty comprehensively on the RPi website (linked below). Most recent projects in EDS, have used Raspbian. If you connect a display, a keyboard and a mouse to the RPi, it practically is a desktop computer (albeit a little slower than today’s standard).

SD Card

Recommended SD Card:Samsung 64GB EVO Plus

Note that the operating system is run off of the micro SD card. Hence the read/write speeds are crutial. Tal and Jordan found this comparison helpful when deciding which card to buy.

If you are using an SD card larger than 32GB, the setup has a formatting difference.

Cloning SD Card (On Windows): For various purposes, such as creating a backup image or making multiple copies of the current state of Raspberry Pi, follow this guide to make clones of SD Cards. Make sure you have enough storage space when making an image of the SD card! For example, even if there are 3Gb data in 32Gb SD Card, you still need to have more than 32Gb storage space on your machine.

Accessing Files on RPi from Windows: Use this freeware to read/write files on RPi from Windows.

OS Installation

Comprehensive tutorial from Raspberrypi.org
If you already know how to do this and just need the link: NOOBS

Finding RPi IP Address

On the RPi find the IP address by opening up a terminal and typing: ifconfig. Under wlan0 you will find the IP address.
It will look something like this 

...
wlan0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        inet 192.168.0.104 netmask 0xffffff00 broadcast 192.168.0.255
...

If the IP were to change, you can find it again using this method.

Controlling over SSH

You can run the RPi in what is called a ‘headless’ mode. This means no screen, no keyboard and mouse or other conventional control peripherals. In order to control the RPi in this manner, you can connect to it over SSH. Most RPis the studio have an onboard WiFi antenna and are capable of connecting to the studio’s wireless network (eds2g or Morse Things network).

  1. In order to connect to the RPi over SSH you first need to make sure your laptop and the RPI are connected to the same wireless network. Because eduroam and SFUNET-SECURE require extra steps, the easiest choice is eds2g or eds5g when working in the studio.

  2. Back on your laptop open up a Linux terminal and type the following command and hit enter:
    ssh pi@192.168.0.101 (where 192.168.0.101 is the IP address of your specific RPi). If you don’t know your RPi’s IP, see above.

  3. If the RPi is on and has an active internet connection, you should see the following response: pi@192.168.0.101's password:

  4. You can then type the password to user ‘pi’ on the RPi and confirm with Enter.

Once your in, you can navigate the RPi just like you would any Linux machine, using ls, cd, touch, mkdir, etc.

In case you are setting up a new RPi and running it in headless mode, this website does a good job of explaining how you make a RPi connect to a WiFi network without ever requiring so much as a mouse or keyboard for the RPi itself. Handy if you’re working on a laptop and have no external keyboard/mouse or display available.

Connecting over VNC

The RPi also has VNC software installed. In case you require the desktop environment of the RPi, but can’t connect a display to it, you can use your own VNC software to connect to the RPi.

  1. On your laptop, download VNC Viewer. Note that unless you will need to be streaming your desktop, you just need VNC Viewer, not VNC Server. Also note that the titles on the VNC website make it confusing as to which program you’re downloading.

  2. Make sure VNC on RPi is up to date
    sudo apt-get update
    sudo apt-get install realvnc-vnc-server realvnc-vnc-viewer

  3. Enable VNC Server graphically
    On your Raspberry Pi, boot into the graphical desktop.
    Select Menu > Preferences > Raspberry Pi Configuration > Interfaces. Ensure VNC is Enabled.

  4. On your laptop, VNC Viewer, enter the IP address of the RPi. This is like selecting a particular chanel on a TV. If you don’t know your RPi’s IP, see above

  5. It should connect and you will be able to see the desktop of the RPi on your laptop.

  6. If you have trouble connecting, particularly if you receive VNC Server not currently listening for Cloud connections. click on VNC in the menubar of the RPi. Then go to the hamburger menu and select Licensing, then login.
    If that doesn’t work, then go through this check list.

Connecting to Pi over Cloud (on VNC)

Follow this instruction to create a VNC cloud account and list devices under the account to get cloud access to Pi from anywhere.

Creating unique names for RPi’s

When working remotely frequently with multiple RPi’s, it might be advisable to give the RPi’s unique names. This means seeing: pi@capra-collector1 in the terminal instead of the default: pi@raspberrypi

This is done simply by opening the terminal in Raspbian (or connecting over SSH) and typing sudo raspi-config, followed by pressing enter. You now get a menu that looks like this: raspi-config menu

Use the arrow keys to choose Network Options, and then change the hostname. The RPi will have to reboot after changing the hostname but will then show up with the name in the terminal.

Programs to Install

Here’s a few recommended programs consider installing

Program Link / Code
Processing https://pi.processing.org
SQLite Browser sudo apt-get install sqlitebrowser
Vim sudo apt-get install vim
xclip sudo apt-get install -y xclip
xscreensaver sudo apt-get install xscreensaver

Locations of Things

| What | Location | |——–|————| |WiFi Passwords| /etc/wpa_supplicant/wpa_supplicant.conf| |Startup Services|/lib/systemd/system/sample.service|

Update Python version

All new projects should start with at least Python 3.7.x. If you aren’t sure the version on your machine, you can run python3 --version to check.
Instructions to update Python version `

Programming the RPi

In the past I’ve edited code on the RPi (i.e. not headless, but while connecting the RPi to a display, keyboard and mouse). This is also possible, but the code editor on the RPi does not come close to the code editor you’re using on your laptop in terms of ease of use. Besides, the RPi is a somewhat slow computer, so typing can lag behind. - Tal Amram

IO Programming

import RPi.GPIO as gpio

gpio.setmode(gpio.BCM)
gpio.setup(24, gpio.OUT)
gpio.output(24, True)

Save As: foo.py
Run: python3 ./foo.py

Helpful Commands

|What|Command| |—-|——-| |Python version|python --version| |Shutdown|sudo shutdown -h now| |Reboot|sudo reboot| |View python scripts running|pgrep -af python| |Kill process|sudo kill -9 [pid]| |Set WiFi Network Passwords|sudo vim /etc/wpa_supplicant/wpa_supplicant.conf
wpa_cli -i wlan0 reconfigure|

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