Raspberry Pi User Guide

1. Meet the Raspberry Pi: A Unique, Affordable Computer

The Raspberry Pi is cheap enough to buy with a few weeks’ pocket money, and you probably have all the equipment you need to make it work: a TV, an SD card that can come from an old camera, a mobile phone charger, a keyboard and a mouse.

A computer for everyone. The Raspberry Pi was created to make computing accessible and affordable, especially for education. Unlike expensive, locked-down devices, it's a small, general-purpose computer designed to be tinkered with, costing around the price of a textbook and utilizing common household items as peripherals. This low barrier to entry encourages experimentation without fear of breaking costly equipment.

Different architecture. At its core, the Pi uses an ARM processor (BCM2835) unlike the x86 chips in most desktops. This means standard Windows or OS X software won't run directly, but its low power consumption allows it to run off a simple micro-USB power supply without needing bulky heatsinks. The Pi runs Linux, an open-source operating system, which is freely available and can be modified to suit various needs.

More than a desktop. While capable of basic desktop tasks, the Pi excels in areas like multimedia and physical computing. Its powerful GPU handles HD video playback, making it ideal for media centers, and its exposed GPIO pins allow it to interact directly with electronic components. This versatility opens doors to projects like robotics, sensor systems, and custom servers, going beyond typical PC uses.

2. Getting Started: Connecting Peripherals & Flashing the SD Card

To prepare a blank SD card for use with the Raspberry Pi, you’ll need to flash an operating system onto the card.

Essential connections. To use your Raspberry Pi, you'll need to connect a display, keyboard, and mouse. Displays can connect via HDMI (for modern monitors/TVs) or composite video (for older TVs), though HDMI offers better quality. Audio is available via HDMI or a 3.5mm jack. Input devices like keyboards and mice connect via USB ports, potentially requiring a powered USB hub if using a Model A or multiple devices.

Storage is key. The Pi uses an SD card as its primary storage, holding the entire operating system and user files. Unlike traditional hard drives, the SD card needs to be "flashed" with a specific operating system image, not just copied onto. This process creates an exact replica of a pre-configured system on the card.

Flashing the OS. Flashing involves using a special utility (like dd on Linux/OS X or Win32 Disk Imager on Windows) to write the operating system image file onto the SD card. This overwrites any existing data on the card. It's crucial to select the correct drive when flashing to avoid accidentally erasing data on your main computer's hard drive.

3. Navigating Linux: The Pi's Open-Source Operating System

Unlike Windows or OS X, Linux is open source: it’s possible to download the source code for the entire operating system and make whatever changes you desire.

Why Linux? The Raspberry Pi runs GNU/Linux, an open-source operating system chosen for its flexibility, low resource requirements, and modifiability. This contrasts with the closed-source nature of Windows and OS X. Linux distributions (like Debian, Fedora Remix, Arch Linux) are tailored versions, offering different software sets but sharing a common core.

Terminal vs. GUI. Linux offers two main ways to interact: the graphical user interface (GUI), familiar from Windows/OS X, and the command line interface (CLI), known as the console or terminal. While GUIs like LXDE (used in Debian) provide point-and-click ease, mastering basic terminal commands is essential for system administration and scripting.

Basic commands and structure. Key terminal commands include ls (list files), cd (change directory), mv (move/rename), rm (remove files), mkdir (make directory), and sudo (run as root user). The file system is structured hierarchically under a single root (/), unlike Windows' drive letters. Important directories include /home (user files), /etc (configuration), and /dev (device files).

4. Solving Problems: Common Troubleshooting Tips

Many problems with the Raspberry Pi can be traced to an inadequate power supply.

Power issues. Insufficient power is a frequent cause of Pi problems, from repeating keyboard characters to intermittent crashes. The Pi requires a stable 5V supply, drawing up to 700mA (Model B). Standard computer USB ports or low-power phone chargers often can't provide enough current. Using a powered USB hub or a dedicated 1A (or higher) power supply is recommended.

Peripheral conflicts. Keyboards and mice can sometimes cause issues, either by drawing too much power or due to chipset incompatibility. Symptoms include jerky mouse pointers or repeating keys. Checking online compatibility lists and using a powered USB hub can help mitigate these problems.

Boot and display. If the Pi's power light is on but the OK light is off and nothing appears on screen, the SD card is likely the issue. This could be due to a bad flash, a corrupted file system, or SD card incompatibility (especially with some high-speed cards). Display problems (shifted image, wrong resolution, black and white) often stem from incorrect video settings, which can be adjusted in configuration files.

5. Getting Online: Wired and Wireless Networking

For most users, configuring the Pi’s network is as easy as plugging a cable into the Model B’s Ethernet port...

Wired simplicity. The Raspberry Pi Model B includes a built-in Ethernet port for wired networking. Connecting it to a router or switch usually results in automatic configuration via DHCP. The port supports auto-MDI, allowing the use of standard or crossover cables. Manual configuration is possible by editing the /etc/network/interfaces file if DHCP is unavailable or a static IP is desired.

Adding wireless. Neither Pi model includes built-in Wi-Fi, but wireless connectivity can be added using a USB wireless adapter. These adapters often require specific firmware to be installed in Linux. It's crucial to check adapter compatibility with Linux and ensure it supports your network's standard and encryption type. USB Wi-Fi adapters can be power-hungry, often requiring a powered USB hub.

Configuration details. Wireless setup involves identifying the adapter (using dmesg or lsusb), installing the correct firmware (often via apt-get), and configuring the connection details (SSID, password, encryption type) in the /etc/network/interfaces file and potentially /etc/wpa.conf using tools like nano. Network status can be checked using ifconfig (wired) and iwconfig (wireless).

6. Customizing Your Pi: Essential Configuration Files

Because of its origins in embedded computing, the BCM2835 chip at the heart of the Raspberry Pi doesn’t have anything like a PC’s BIOS menu...

Hardware control (config.txt). Low-level hardware settings on the Pi are controlled via text files in the /boot directory, read when the system powers on. config.txt manages display settings (overscan, resolution, HDMI/composite mode), boot options (kernel selection), and even overclocking parameters. Modifying this file allows fine-tuning the Pi's interaction with peripherals and adjusting performance.

Display adjustments. Common display issues like black borders or shifted images can be fixed by adjusting overscan_ settings or disabling overscan entirely in config.txt. Manual control over HDMI resolution (hdmi_mode, hdmi_group) and composite video format (sdtv_mode) is also possible, useful for incompatible displays. Incorrect settings can prevent the display from working, requiring editing the file on another computer.

Performance tuning. config.txt allows overclocking the CPU, GPU, and memory (arm_freq, gpu_freq, sdram_freq) for performance gains, but this can reduce the chip's lifespan and potentially void the warranty, especially if overvoltage settings (over_voltage) are used. Memory partitioning between the CPU and GPU is controlled by selecting different start.elf files in /boot, allowing users to allocate more RAM to the CPU for general tasks at the expense of graphics performance.

7. Beyond the Desktop: Media, Productivity, and Web Serving

One of the most popular tasks for a Pi to carry out is that of a home theatre PC, or HTPC.

Multimedia powerhouse. The Pi's hardware is optimized for multimedia, making it an excellent HTPC. It can play HD video (H.264) and various audio formats. Dedicated distributions like Rasbmc (based on XBMC) provide user-friendly interfaces for playing local media, streaming from network shares (UPnP, SMB, NFS), and accessing online content via add-ons.

Productivity on a budget. The Pi can function as a basic productivity machine using cloud-based office suites (Google Drive, Zoho) accessed via a web browser like Chromium, or by installing local applications like OpenOffice.org and The Gimp. While performance may be slower than a desktop, these options provide essential word processing, spreadsheet, presentation, and image editing capabilities. Installing larger suites requires sufficient SD card space, potentially necessitating partition resizing.

Serving the web. Despite its modest power, the Pi can act as a web server, ideal for low-traffic sites or local network use. Installing a LAMP stack (Linux, Apache, MySQL, PHP) turns the Pi into a capable server for dynamic websites. Platforms like WordPress can be installed on the Pi, allowing users to host their own blogs or content management systems, though performance will be limited compared to commercial hosting.

8. Learn to Code: Programming with Scratch and Python

The chief goal of the Raspberry Pi project is to get people writing their own programs...

Scratch for beginners. Scratch is a visual, drag-and-drop programming language designed for young children (ages 8+). It introduces core programming concepts like loops, conditionals, and events through connecting graphical blocks. Scratch is pre-installed on the recommended Debian distribution and is excellent for creating interactive stories, animations, and simple games, serving as a gentle introduction to programmatic thinking.

Python's power. Python is a flexible, high-level text-based language recommended for progressing from Scratch. Known for its clear, readable syntax, Python is used for a wide range of applications, from simple scripts to complex web applications and games (using libraries like pygame). Python programs are text files containing instructions, executed by the Python interpreter.

Getting started with Python. Writing Python involves using a text editor or an Integrated Development Environment (IDE) like IDLE. Basic concepts include print (output), raw_input (input), variables, loops (while, for), and conditionals (if, elif, else). Python's versatility and extensive libraries make it a powerful tool for controlling hardware, building applications, and interacting with networks.

9. Connect to the World: Hardware Hacking with GPIO

The Pi has another trick up its sleeve, though, which places it above and beyond the capabilities of the average PC: its 26-pin general-purpose input-output (GPIO) port...

Physical computing. The GPIO port (P1) is the Pi's unique feature, allowing it to interact with the physical world. These 26 pins include power (3.3V, 5V, Ground), general-purpose I/O pins, and dedicated buses (UART, I²C, SPI). The Pi's internal logic is 3.3V, so connecting 5V components directly can cause damage.

Basic components. Getting started requires basic electronics components like a breadboard (for prototyping), jumper wires, resistors, push-buttons (input), and LEDs (output). Understanding resistor color codes and calculating current-limiting resistors for LEDs is essential for building safe circuits.

GPIO in Python. A Python library (like RPi.GPIO) is needed to easily control the GPIO pins from code. Pins must be configured as inputs (GPIO.IN) or outputs (GPIO.OUT). GPIO.output(pin, True/False) sets an output pin high or low, while GPIO.input(pin) reads the state of an input pin. Simple circuits like flashing an LED or reading a button demonstrate these concepts.

Beyond prototyping. For more permanent projects, stripboard and soldering equipment are used to create robust circuits. While breadboards are great for experimentation, they are less durable. Add-on boards like the Gertboard can provide protection and additional functionality, bridging the gap between the Pi and external electronics.

Last updated: May 6, 2025