A Tour of the Boards

There have been quite a few different versions of the Raspberry Pi board. The first version was the Raspberry Pi 1 Model B, which was followed by a simpler and cheaper Model A. In 2014, the Raspberry Pi Foundation announced a significant revision (and improvement) in the board design: the Raspberry Pi 1 Model B+. The Model B+ set the form-factor for “mainline” Raspberry Pis for the foreseeable future. Since then, the Foundation has also created a device for embedding the Pi in products, called the Compute Module. In 2015, it also released a stripped-down $5 model called Raspberry Pi Zero. And as of February 2016, Raspberry Pi 3 Model B is the latest mainline Raspberry Pi. A few different types of Raspberry Pis are pictured in Figure 1-1.

Figure 1-1. There are many versions of the Pi, and here are a few (clockwise from top left): Raspberry Pi 3 Model B, Raspberry Pi 1 Model A+, Raspberry Pi Compute Module, and Raspberry Pi Zero. As of February 2016, Raspberry Pi 3 Model B is the latest mainline Raspberry Pi.

Let’s start with a tour of what you’ll see when you take your Raspberry Pi out of the box.

It’s tempting to think of Raspberry Pi as a microcontroller development board like Arduino or as a laptop replacement. In fact, it is more like the exposed innards of a mobile device with maker-friendly headers for various ports and functions. Figure 1-2 shows the parts of the board.

Figure 1-2. A map of the hardware interface of the Raspberry Pi

Here’s a description of each part:

1. The processor

   At the heart of the Raspberry Pi is the same kind of processor you’d find in a cell phone. If you’re using Raspberry Pi 3, this is a 64-bit, quad core 1.2 GHz system on a chip, which is built on the ARM architecture. ARM chips come in a variety of architectures with different cores configured to provide different capabilities at different price points. Raspberry Pi 1 has 512 megabytes of RAM and Raspberry Pi 2 and 3 have one gigabyte of RAM.

2. Composite video and analog audio out

   Analog audio and video outputs are available on a standard 3.5mm 4-pole plug connector. One side of the connecting cable is a four-connector mini jack (which looks like a headphone jack), and the other side is three RCA plugs for stereo audio (red and white) and composite NTSC or PAL video (yellow).

3. Status LEDs

   Two indicator LEDs on the board provide visual feedback (Table 1-1). There are also network activity LEDs on the Ethernet jack itself.

   Table 1-1. The status LEDs

   ACT	Green	Lights when the SD card is accessed
   PWR	Red	Hooked up to 3.3V power

   Note

   Starting with Raspberry Pi 3, the status LEDs are placed near the MicroUSB power port as shown in Figure 1-2. For previous boards, you’ll find them near the GPIO pins, in place of the WiFi antenna

4. External USB ports

   On the mainline versions of Raspberry Pi, there are four USB 2.0 ports for connecting peripherals like keyboards, mice, thumb drives, and printers. While many USB devices can be powered from these ports, you may want to consider using a powered external hub if you have peripherals that need more power, such as a hard drive.

5. Ethernet port

   This is a standard RJ45 Ethernet port capable of 10 or 100 megabits per second data speeds. Connect this to your router to get online; otherwise you can use WiFi.

6. HDMI connector

   The HDMI port provides digital video and audio output. Fourteen different video resolutions are supported, and the HDMI signal can be converted to DVI (used by many monitors), composite (analog video signal usually carried over a yellow RCA connector), or SCART (a European standard for connecting audiovisual equipment) with external adapters.

7. Power input

   One of the first things you’ll realize is that there is no power switch on the Pi. This MicroUSB connector is used to supply power (this isn’t an additional USB port; it’s only for power). MicroUSB was selected because the connector is cheap and USB power supplies are easy to find.

8. The microSD card slot

   You’ll notice there’s no hard drive on the Pi; everything is stored on a microSD card. Raspberry Pi 1 and 2 are equipped with spring-loaded slots, so you’ll push to put the microSD card in and push again to take it out. With Raspberry Pi 3, they did away with the spring-loaded component in favor of a friction-fit slot. On that model, you’ll push to insert the microSD card and pull to remove it. Of course, you should only do this when the Raspberry Pi is powered down.

Figure 1-3 shows all of the power and input/output (I/O) pins on the Raspberry Pi.

Figure 1-3. The pins and headers on the Raspberry Pi

Here’s a description of the pins and headers shown:

1. General-purpose input/output (GPIO) and other pins

   The current Raspberry Pis have a 2 × 20 pin GPIO header. Chapters 6 and 7 show how to use these pins to read buttons and switches and control actuators like LEDs, relays, or motors.

2. The Camera Serial Interface (CSI) connector

   This port allows a camera module to be connected directly to the board (see Figure 1-4).

3. The Display Serial Interface (DSI) connector

   This connector accepts a 15-pin, flat ribbon cable that can be used to communicate with the official Raspberry Pi touch display.

Figure 1-4. The Raspberry Pi camera module connects directly to the CSI connector. See Chapter 9 for a full discussion of cameras and the Pi.

The Proper Peripherals

Now that you know where everything is on the board, you’ll need to know a few things about the proper peripherals to use with the Pi. There are a bunch of prepackaged starter kits that have well-vetted parts lists; there are a few caveats and gotchas when fitting out your Raspberry Pi. There’s an extensive list of supported peripherals on the eLinux.org wiki, but these are the most basic:

A power supply

This is the most important peripheral to get right; you should use a MicroUSB adapter that can provide 5V and at least 1,500mA (1.5A) of current for Raspberry Pi 3 and 1,000 mA (1A) for Raspberry Pi 2 and older. A cell phone charger won’t necessarily cut it, even if it has the correct connector. Many cell phone chargers don’t provide enough current, so check the rating marked on the back. An underpowered Pi may still seem to work but will be flaky and may fail unpredictably. If in doubt, use the official Raspberry Pi power supply, which is available at most places where Raspberry Pis are sold.

There are also a number of battery-pack solutions for taking your Raspberry Pi on the go; the same rules about voltage and current apply there as well.

A microSD card

You’ll need at least 8 GB, and it should be a Class 10 card for the best read and write performance. There are operating systems that fit onto SD cards with less than 8 GB, but the standard Raspbian installation requires at least an 8 GB microSD card.

USB keyboard and mouse

They’ll be helpful for controlling your computer. These peripherals are fairly generic, so no need to use anything fancy.

An HDMI cable

If you’re connecting to a monitor, you’ll need this, or an appropriate adapter for a DVI monitor. You can also run the Pi headless, as described later in this chapter. HDMI cables can vary wildly in price. If you’re just running a cable three to six feet to a monitor, there’s no need to spend more than $3 on an HDMI cable. If you are running long lengths, you should definitely research the higher-quality cables and avoid the cheap generics.

Ethernet cable

Your home may not have as many wired Ethernet jacks as it did five years ago. Because everything is wireless these days, you might find the wired port to be a bit of a hurdle; see the section “Getting Online” for some alternatives to plugging the Ethernet directly into the wall or a hub.

WiFi USB dongle

If you’re using Pi 1 or 2, you may want to add a WiFi dongle for wireless Internet access. Many 802.11 WiFi USB dongles work with the Pi out of the box. WiFi uses a lot of power, so you will need to make sure you have an adequate power supply; a 2A supply or a powered USB hub is a good choice. If you are having problems with a WiFi dongle, power is almost always the problem.

You may also want to consider some of the following add-ons:

A powered USB hub

If you want to add more than four USB devices to a mainline Raspberry Pi, you’ll need a USB hub. A powered USB 2.0 hub is recommended.

Heatsink

A heatsink is a small piece of metal, usually with fins, that creates a lot of surface area to dissipate heat efficiently. Heatsinks can be attached to chips that get hot. The Pi’s chipset was designed for mobile applications, so a heatsink isn’t necessary most of the time. However, as we’ll see later, there are cases where you may want to run the Pi at higher speeds, or crunch numbers over an extended period, and the chip may heat up a bit. Some people have reported that the network chip can get warm as well.

Real-time clock

You may want to add a real-time clock chip (like the DS1307) for logging or keeping time when offline.

Camera module

A $25 Raspberry Pi camera module is available as an official peripheral. You can also use a USB webcam (more on this in Chapter 9).

LCD display

Many LCDs can be used via a few connections on the GPIO header. Look for a TFT (thin-film transistor) display that can communicate with the Pi using the SPI (Serial Peripheral Interface) pins on the header. The Raspberry Pi Foundation also has a touch display that conencts to the DSI interface on the Raspberry Pi.

Sound cards

You’ll probably find that the built-in analog audio is inadequate for most of your projects. If you want high-quality sound output (or input) from the Pi, you’ll need a sound card. Many USB sound cards also work well with the Pi; the Behringer’s U-Control devices are a popular, inexpensive option.

Laptop dock

Several people have modified laptop docks intended for cell phones (like the Atrix lapdock) to work as a display/base for the Raspberry Pi. Some companies like Pi-Top create a laptop-like device specifically for Raspberry Pi.

HATs

A number of vendors and open hardware folks have released add-on daughterboards that sit on top of the Pi and connect via the GPIO header. These boards add capabilities like driving LCDs, motors, or analog sensor inputs. If you’re familiar with Arduino terminology, you might call these daughterboards “shields,” but the Raspberry Pi Foundation calls them HATs (Hardware Attached on Top), see Figure 1-5. The full specification is available on the Raspberry Pi Foundation’s GitHub page.

Figure 1-5. The Sense HAT add-on board includes an LED matrix, a suite of sensors, and a joystick input. It was designed for the Raspberry Pis that were sent to the International Space Station.

To share just one example, the Raspberry Pi Foundation makes a HAT called the Sense HAT, which includes an RGB LED matrix; sensors for temperature, pressure, and humidity; an accelerometer; a gyroscope; and a magnetometer. It also has a five-position joystick. It’s the HAT that was designed for the Raspberry Pis that were sent to the International Space Station as part of the Foundation’s Astro Pi program.

The Case

You may find that you want a case for your Raspberry Pi. The stiff cables on all sides make it hard to keep flat, and some of the components like the SD card slot can be mechanically damaged even through normal use.

There are a bunch of premade cases available, but there are also a lot of case designs available to download and fabricate on a laser cutter or 3D printer. In general, avoid tabbed cases where brittle acrylic is used at right angles. The layered acrylic of the Pibow is a colorful option (Figure 1-6).

The Raspberry Pi Foundation also creates an official case, which uses a nice injection-molded design. It has multiple parts that can be removed to allow access to the GPIO pins and other components. (Figure 1-7).

It should probably go without saying, but it’s one of those obvious mistakes you can make sometimes: make sure you don’t put your Raspberry Pi on a conductive surface. Flip over the board and look at the bottom; there are a lot of components there and a lot of solder joints that can be easily shorted. Another reason why it’s important to case your Pi!

Figure 1-6. The colorful Pibow case from Pimoroni

Figure 1-7. With the official Raspberry Pi case, you can remove the top and sides to access the different parts of the board.

Choose Your Distribution

The Raspberry Pi runs Linux for an operating system. Linux is technically just the kernel, but an operating system is much more than that—it’s the total collection of drivers, services, and applications that makes the OS. A variety of flavors or distributions of the Linux OS have evolved over the years. Some of the most common on desktop computers are Ubuntu, Debian, Fedora, and Arch. Each has its own communities of users and is tuned for particular applications.

Because the Pi is based on a mobile device chipset, it has different software requirements than a desktop computer. The Broadcom processor has some proprietary features that require special “binary blob” device drivers and code that won’t be included in any standard Linux distribution. And, while most desktop computers have gigabytes of RAM and hundreds of gigabytes of storage, the Pi is more limited in both regards. Special Linux distributions that target the Pi have been developed.

In this book, we will concentrate on the official Raspbian distribution, which is based on Debian. Note that raspbian.org is a community site, not operated by the Foundation. If you’re looking for the official distribution, visit the Raspberry Pi Foundation’s downloads page. Other specialized distributions are explored in Chapter 3.

Flash the SD Card

Many vendors sell SD cards with the operating system preinstalled; for some people, this may be the best way to get started. Even if it isn’t the latest release, you can easily upgrade once you get the Pi booted up and on the Internet.

The easiest way to get the OS on the microSD card is to use the NOOBS tool. Don’t take offense; no one is questioning your computer acumen. NOOBS stands for New Out Of the Box Software and is a configuration tool that will help install the OS. You’ll need an SD card (at least 8 GB) and reader, then follow these steps: when you boot up the Pi, you’ll see a configuration screen with a number of OS options. Select Raspbian and hit the Install button; that’s all there is to it!

Booting Up

Follow these steps to boot up your Raspberry Pi for the first time:

1. Push the microSD card into the socket on the bottom of the board. On Raspberry Pi 1 and 2, it’ll click into place. On Raspberry Pi 3, the microSD card won’t click and is held in place with friction.

2. Plug in a USB keyboard and mouse.

3. Plug the HDMI output into your TV or monitor. Make sure your monitor is on and set to the correct input.

4. Last, plug in the power supply. It’s a good habit to make sure everything else is hooked up before connecting the power.

If all goes well, you should see a bunch of startup log entries appearing on your screen. At the top, you’ll see a Raspberry Pi logo, or four if you’re using a quad core model (Raspberry Pi 2 or later). If things don’t go well, skip ahead to “Troubleshooting”. These log messages show all of the processes that are launching as you boot up the Pi. You’ll see the network interface be initialized, and you’ll see all of your USB peripherals being recognized and logged. You can see these log messages after you log in by typing dmesg on the command line.

Configuring Your Pi

The very first time you boot up, you’ll be presented with the Raspbian desktop environment. The first thing you’ll want to do is set a few settings with the Raspberry Pi Configuration tool. To open it, click Menu→Preferences→Raspberry Pi Configuration (see Figure 1-8).

Next, in Figure 1-9, we’ll show you which configuration options are essential and which you might want to come back to if you need them.

Figure 1-8. How to launch the Raspberry Pi Configuration tool

Figure 1-9. The Raspberry Pi Configuration tool allows you to change many of the important settings on your Raspberry Pi.

System → Expand Filesystem

You should always choose this option; this will enlarge the filesystem to let you use the whole microSD card. On the newest versions of Raspbian, this will be done automatically the first time you boot.

System → Change Password

If you’re on a network with others, it’s a good idea to change the default password from “raspberry” to something a little stronger.

System → Boot

This option lets you boot straight to the graphical desktop environment and is set this way by default. If you select CLI, you’ll get the command line when you boot up, and you’ll have to start the graphical interface manually with the command startx.

System → Overscan

The overscan option is set to enabled at first because some monitors may cut off the edges of the desktop. If you have a black border around your desktop, then you can disable overscan to get the desktop to fill your screen.

Interfaces → SSH

This option turns on the Secure Shell (SSH) server, which will allow you to log in to the Raspberry Pi remotely over a network. This is really handy, so you should leave it on.

Performance → GPU Memory

This option allows you to change the allocation of RAM available to the graphics processing unit. The rest of the RAM is left for the CPU to use. It’s best to leave the default split for now. If you decide to experiment with 3D graphics or video decoding, you may want to adjust this value in the future.

Performance → Overclock

With this option, you can run the processor at speeds higher than the default operation. This option is not available for Raspberry Pi 3. For now, it’s best to leave this setting alone.

Localisation → Set Keyboard

The default keyboard settings are for a generic keyboard in a UK-style layout. If you want the keys to do what they’re labeled to do, you’ll definitely want to select a keyboard type and mapping that corresponds to your setup. Luckily, the keyboard list is very robust. Note that your locale settings can affect your keyboard settings as well.

Localisation → Set Locale

If you’re outside the UK, you should change your locale to reflect your language and character encoding preferences. The default setting is for UK English with a standard UTF-8 character encoding (en_GB.UTF-8). Select en_US.UTF-8 if you’re in the US.

Localisation → Set Timezone

You’ll probably want to set this.

When you’re done, select OK and you’ll be prompted to restart so that the settings can take effect.

If you want to access these settings from the command line, you can use the raspi-config tool (see Figure 1-10). Type the following at the command line if you want to try that out:

sudo raspi-config
 

Figure 1-10. The raspi-config tool when run from the command line

Getting Online

You’ve got a few different ways to connect to the Internet. If you’ve got easy access to a router, switch, or Ethernet jack connected to a router, just plug in using a standard Ethernet cable. If you have a WiFi USB dongle or you’re using a Raspberry Pi 3, you can connect wirelessly; there’s an icon on the taskbar to set up your wireless connection (see Figure 1-11).

Figure 1-11. Click on the network icon on the right side of the taskbar to select a WiFi network to connect to.

If you’ve got a laptop nearby, or if you’re running the Pi in a headless configuration, you can share the WiFi on your laptop with the Pi (Figure 1-12). It is super simple on the Mac: just enable Internet Sharing In your Sharing settings, then use an Ethernet cable to connect the Pi and your Mac. In Windows, enable “Allow other network users to connect through this computer’s Internet connection” in your Internet Connection Sharing properties. The Pi should automatically get an IP address when connected and be online.

You will probably need a cross-over cable for a Windows-based PC, but you can use any Ethernet cable on Apple hardware, as it will autodetect the type of cable.

Figure 1-12. A handy trick is to share your laptop’s WiFi connection with the Pi. You can also run the Pi headless (see “Running Headless”), which is convenient if you’re using your Raspberry Pi on the run.

Shutting Down

There’s no power button on the Raspberry Pi (although there is a header for a reset switch on newer boards). The proper way to shut down is through the Shutdown command under the taskbar menu within the desktop environment.

You can also shut down from the command line by typing:

pi@raspberrypi ~ $ sudo halt

Be sure to do a clean shutdown (and don’t just pull the plug). In some cases, you can corrupt the SD card if you turn off power without halting the system.

Troubleshooting

If things aren’t working the way you think they should, there are a few common mistakes and missed steps. Be sure to check all of the following suggestions:

• Is the microSD card in the slot, and is it making a good connection? Are you using the correct type of microSD card?

• Was the disk image written correctly to the card? Try copying it again with another card reader.

• Check the integrity of your original disk image. You can do this by running a Secure Hash Algorithm (SHA) checksum utility on the disk image and comparing the result to the 40-character hash published on the download page.

• Is the Pi restarting or having intermittent problems? Check your power supply; an underpowered board may seem to work but act flaky.

• Do you get a kernel panic on startup? A kernel panic is the equivalent of Windows’ Blue Screen of Death; it’s most often caused by a problem with a device on the USB hub. Try unplugging USB devices and restarting.

If that all fails, head over to the Raspberry Pi Hub’s troubleshooting page for solutions to all sorts of problems people have had.

Going Further

The Raspberry Pi Hub

Hosted by elinux.org, this is a massive wiki of information on the Pi’s hardware and configuration.

List of Verified Peripherals

The definitive list of peripherals known to work with the Raspberry Pi.