Although the Pi A+, B+, and Model 2-B are used for all of our projects, nothing covered in this book precludes the use of the older A and B models. The Pi you purchased might be sourced from many different suppliers. There are some critical differences that you need to be aware of if you plan to use the Pi for a hobby project or education tool:

If you compare other revisions of the Pi with the following image, you will notice that there are some orientation and position changes for connectors and different mounting holes on the A+, B+, and Model 2-B as compared to the A and B models:

We suggest that you consider a complete kit of parts as a good starting point—if you haven't already bought your Pi. In particular, there are kits from Canakit.com for around $90. The kit includes everything needed for a new Pi project designer.

Configure power for Pi

It is important to know that an insufficient power supply current capability could result in an installation that is unreliable and proves hard to diagnose when problems occur. It's OK to have a power supply capable of delivering more current than needed; the system only draws the current it requires.

The most common guidance for the Pi B is a 5-Volt power supply providing between 700 mA and 1 Amp and for the Pi B+ and Model 2-B, between 600 mA and 2 Amp. The higher power requirements for the Pi B+ and Pi 2-B (four USB connections) enable connection to a wide range of USB peripherals such as USB disks, portable printers, scanners, and so on.

Note

Note that the Pi B+ and Pi 2-B have internal current limits of 600 mA set on the USB ports; exceeding the current will power off the port momentarily. The USB 2.0 specification recommends a maximum peripheral device current specification of 500 mA. You should ensure that heavy current peripherals are supported via an externally powered USB hub for the best reliability.

We used an AmazonBasics seven-port USB hub (see the following image) which has two ports that can provide over 1.2 Amp each, and five more ports that can provide up to 500 mA per port. It has a power supply rated for 5V at 4A, which cannot support maximum power on every port simultaneously (rarely required in any realistic configuration).

Our multi-Pi development environment is shown in the following image:

Before you can decide how to power your Pi, you must determine the highest level of current required to ensure that your devices can be properly supported in the configuration. We will continue to discuss power issues as they arise throughout the projects.

Our Pi is powered by a single AmazonBasics hub. The Pi and the hub are attached to a small piece of medium-density fibreboard (MDF) board using Velcro, which is an easy way to connect peripherals while designing a project. There is a WiFi adapter, keyboard, and mouse plugged into the hub. We normally connect via an Ethernet network interface, which facilitates the testing of a broader range of networking scenarios. You will notice in our configuration that a Pi-cam is connected and that we have a Microsoft webcam at the top of the right-hand side speaker.

A development desktop power/USB configuration like the one we showed in the preceding image will provide you with a stable development platform for our project designs. Of course, most final designs may require only the four USB ports on the motherboard and consume as little as 300 mA on average. The following list is the minimum configuration required to complete the projects in this book:

• A 5-V micro-USB power source rated at 2 A
• A USB mouse and keyboard
• An HDMI cable and an HDMI display, or an HDMI-to-DVI cable and a DVI display, or an HDMI-to-VGA convertor and a VGA LCD display
• An Ethernet cable and connection to your home network or a WiFi adapter for connecting to your WLAN

To enable remote access to your Pi from a PC, Mac, or even a smartphone, you must first configure the bootloaders (the initial code that starts the processor) and the operating system on the SD card. Once you configure the OS, it's easy to make the Pi headless.

We use a physical monitor, keyboard, and mouse in our development environment. This configuration allows us to use the graphical desktop, see early error messages, and use advanced bootloader capabilities, such as multi-boot, to select from various configured operating systems that we build.

In our dual-Pi development environment, we have the screen, keyboard, and mouse connected to one Pi and then typically remote into the other using PuTTy or MSTSC (an RDP client) for remote access from a PC. Throughout this book, we will assume you have a connected keyboard, mouse, and display until a project actually requires a headless and wireless configuration.

The most modern LCD monitors may have two or more HDMIs, or one HDMI and one DVI or DisplayPort—a much newer display standard). The Pi supports a single HDMI connection and a much more primitive composite video connection, neither of which can connect to VGA directly.

The Pi HDMI interface supports up to 1920 x 1200 pixels and provides the best possible desktop resolution. It may also support sound output over HDMI if the monitor includes speakers.

A composite video connection on the Pi can support up to 800 x 600 pixels depending on the monitor, most of which will typically only work at 640 x 480 pixels. However, a composite image could show some artifacts such as position errors or visible shading lines or bars. Composite monitors, which tend to be quite small, are often used for portable and auto-embedded systems.

When using the Pi, the following video output configurations are possible:

The following image show the types of display/video cables that are supported with the Pi:

hdmi_force_hotplug=1
hdmi_group=2
hdmi_mode=9
hdmi_drive=2

Your Pi kit will typically include an SD Card. The Pi A and the Pi B use a standard-sized SD Card, and the Pi A+, B+, and Model 2-B use a Micro SD Card. Most of these SD Cards provided in kits are preconfigured with NOOBS. Once initialized, Raspbian or another optional operating system will install from an image already on the SD Card or from a network connection.

The minimum recommended SD Card size for the current version of Raspbian (February 2015 Debian 7:7.6 Wheezy) is 4 GB. This version results in a Raspbian install limited to a 2.7 GB partition. Most Pi kits come with a minimum SD Card size of 8 GB, allowing either multiple OS installations or a very large Raspbian partition.

The latest revision (1.4.0) of the new out-of-the-box software (NOOBS) is available in two versions:

Depending on which version of Pi you have, you might need to have both the standard and Micro SD cards. We suggest that you only buy Micro SD cards that can be used for all Pi versions with a Micro SD-to-SD Card adapter.

With the addition of a Micro SD Card reader (Micro SD to USB), you have the greatest flexibility when formatting and initializing SD Cards. You can even reformat and initialize Micro SD Cards using the Pi once you have a working copy of Raspbian. The following image shows you the standard SD and the Micro SD Cards, and their capabilities:

SD Cards have a specified speed or Class, typically Class 4 or Class 10. Class 4 cards are quite adequate for the application and typically cost less.

If you bought a kit with a prepared Micro SD Card, then you are ready to boot your Pi system. If you have a blank or previously used Micro or Standard sized SD Card, go to the Chapter 1 folder at http://1drv.ms/1ysAxkl to locate the How to Initialize SD Card instructions.

You are now ready to connect your Pi to a screen, keyboard, mouse, and a suitable power supply or USB hub. After inserting the Micro SD Card, you have one more decision to make—are you connecting to a network cable?

If you purchased an SD Card with a full copy of NOOBS or have just built the full copy (700 MB NOOBS install), then you don't need a network connection yet; you are ready to go.

If you built NOOBS Lite, you will need an Ethernet cable to connect to the network. Plug this cable into an Ethernet port on your network. The WAP or network needs to support DHCP, which is normally the way most home networks are configured. The IP address is allocated automatically when the Pi boots up and starts the NOOBS software.

After restarting your Pi, the Raspbian graphical desktop appears, and you are logged in as pi with the password as raspberry (if you did not change it).

Notice that the desktop is uncluttered. All the current GUI applications are located in the menu and five applications are on the quick launch bar. From the Menu/Shutdown, you can Shutdown, Reboot, or Logout. The following is a list of quick pointers of handy keyboard accelerators that you might find useful:

There are multiple downloadable files for each of the chapter projects, along with extra procedural documents; they are available for download from http://1drv.ms/1ysAxkl.

You can access them from your Raspberry Pi desktop by performing the following steps:

Now that you've built and configured your Pi as a working desktop system that boots directly to the graphical desktop interface, let's review some of the important tasks you learned to perform:

In the next chapter, you will use Raspbian desktop tools and the shell command line to build a talking clock using scripts and Python 3.