Chapter 1. Kick-Start Your Raspberry Pi Zero

In this chapter, we will cover the following recipes:

Understanding the standard connectors and test points
Reviewing power supply requirements
Choosing an operating system to install
Writing to an SD card with NOOBS
Using Windows to write a Raspbian image to an SD card
Using OS X to validate a Raspbian image and write it to an SD card
Using Ubuntu 16.04 to validate a Raspbian image and write it to an SD card
Identifying RCA solder points for analog video connections
Adding a USB extension over a USB OTG connector
Connecting to displays and changing the configuration settings
Logging in to the RPZ desktop for the first time, creating users, and rebooting

Introduction

The smallest, most inexpensive member of the Raspberry Pi family, the Zero, has once again improved upon its promise of computer accessibility to everyone in the world. At 40 percent of the size of the larger Raspberry Pis and a fraction of the cost (around 5 US dollars), the Raspberry Pi Zero opens more doors to portability, data collection, and experimentation while being affordable so that anyone can get started, anywhere, on learning about computers, Linux, and the Internet of Things.

With such a small form factor, there are some sacrifices made compared to the full-size Raspberry Pi. It uses the same single-core chip as the original Pi, so it is a bit slower than today's quad-core models. It also has limited physical connections, at least by default, compared to the larger Pi models. This chapter will explore some of the differences and how to work around them and get your Raspberry Pi Zero set up for more interesting recipes. The recipes here will focus on getting familiar with the Raspberry Pi Zero board, deciding on an operating system and methods for creating your first SD card, and getting enough things connected so you can start using your Zero.

Understanding the standard connectors and test points

If you've worked with a Raspberry Pi 1, 2, or 3 before, you will find the Raspberry Pi Zero to be similar, but quite a bit smaller. To accommodate such a small size, several connectors had to be miniaturized or reduced. Taking a close look, you will find that the same potential is contained in this small board. Throughout the following recipes, we will look at the Raspberry Pi Zero, its functional components, and how it compares to the larger Raspberry Pi boards. By the end of this chapter, you will have a running Raspberry Pi Zero!

Getting ready

To get your Raspberry Pi Zero online on HDMI, the following equipment will be needed:

A Raspberry Pi Zero
A micro-USB power adapter, 5 V/1.2 A out
Note
The Raspberry Pi documentation allows up to 2.5 A for the Pi's power supply, in case you don't want to use a powered USB hub. For this cookbook, we will start with a powered USB hub but work toward low-power and low-profile solutions.
A micro-USB OTG (On-The-Go) adapter
A 4-port powered USB hub
A micro-HDMI to standard HDMI adapter and HDMI cable or a micro-HDMI to standard HDMI cable
A micro SD card (4 GB minimum, 8 GB recommended)
A USB keyboard and mouse
A monitor that takes HDMI, or DVI with a DVI-HDMI adapter
A computer with an SD card interface running Mac OS X, Windows, or Linux

Note

A great resource for checking device compatibility are the Raspberry Pi pages in the Embedded Linux wiki ( www.elinux.org ). This has a rather large list of known compatible devices as well as known problematic ones and ones that will likely require a powered USB hub to operate.

How to do it...

Take a look at your Raspberry Pi Zero and examine each of the connections. They really fit a lot into a small space:

Raspberry Pi components

The numbers in the figure denote the following components:

The GPIO header is the same one you will find on the Raspberry Pi B and later versions. The big difference here is that a header hasn't been soldered on. If you project requires your Raspberry Pi to be very thin, then you can solder your connections directly to the board. If you are using your Zero for prototyping, you can attach whichever header makes your life easiest. For this book, we will have the female 90-degree header soldered on for easy interfacing to the Adafruit Pi Cobbler.
The Micro SD card slot is very much the same as previous versions, with the big difference being that it is push-in/pull-out instead of other boards' push-in/push-out slot.
The mini-HDMI port works just like a regular-sized port, though it requires an HDMI mini-to-regular adapter or cable to connect to LCD monitors.
The first USB port is micro-USB, and the only USB port available for data use on the Raspberry Pi Zero. For use with standard USB components such as mice and keyboards, you will need a micro-USB OTG adapter and a powered USB hub. As we move forward in the book, we will discover ways to run "headless" so that not all the connections are required, but to get started, you will want an adapter and a hub.
The second USB port is the Raspberry Pi's power connection, which we will take a closer look at in the next recipe.
This bus is to attach the Raspberry Pi's camera cable.
While RCA video is no longer available on the Raspberry Pi Zero, we will hack it later to understand how to use the older, non-HDMI way to see video.
Finally, on this side of the board, the connectors marked RUN are for resetting the Raspberry Pi. Shorting these connections will reset your Raspberry Pi.

The back side of the board contains test connector points:

Raspberry Pi Zero test pads

Not all the test points are documented for the Raspberry Pi Zero, but several are known:

Label	Function	Label	Function
PP1	5-V-micro USB	PP18	SD_DAT2
PP3	GND	PP19	SD_DAT3
PP4	GND	PP20
PP5	GND	PP22
PP6	GND	PP23
PP8	3.3 V	PP35	GND
PP9		PP36
PP14	SD_CLK	PP37	CAM_GPIO0
PP15	SD_CMD	PP38	CAM_GPIO1
PP16	SD_DAT0	PP39	SCL0
PP17	SD_DAT1	PP40	SDA0

Test points are great for validating that your Raspberry Pi is seeing the right voltage and/or frequencies. Many of the test points require an oscilloscope to observe and are thus beyond the scope of this book, but testing and troubleshooting prototypes is as easy on a Raspberry Pi Zero as it is on one of the larger boards.

Reviewing power supply requirements

One of the outstanding things about the Raspberry Pi Zero is its low power requirement, even compared to its siblings. The power is received through the second micro-USB slot on the board, and it should never need greater than a 5-V/1 A power supply. A well-configured Raspberry Pi in idle state can draw as little as 30 mA, and even under stress, it has not been shown to use more than 350 mA! Your Raspberry Pi Zero could run for free with a small solar panel and rechargeable battery pack. The Raspberry Pi 2 and 3, while more powerful, generally use from two to five times as much power to run.

How to do it...

You can also power your Raspberry Pi Zero over the GPIO ports, though it is important to be careful to have consistent and predictable power so you don't fry your board. The easiest method is certainly to find steady 5V source that works over micro-USB, but with careful design, you can run your board from any power supply with consistent 5 V and current up to 1 A. We will run our Raspberry Pi Zero on batteries later in this cookbook.

Of course, as you add peripherals, there will be a need to draw more current. If on USB, using a powered USB port will help a lot. When working with devices you have connected directly to GPIO, you just need to make sure your Raspberry Pi Zero power source can provide enough current to run the board and what's attached to it.

Until you have an SD card ready, you won't really be able to test the power completely - you can plug the adapter into the Raspberry Pi, but keep it unplugged from the power for now.

Choosing an operating system to install

Because the Raspberry Pi Zero uses the same ARMv6 chip offered in the original Raspberry Pi, it won't be ideal for the latest of all varieties of Linux that the newer generation of models can support. The clear choice right now for the RPZ is Raspbian Jessy. Adafruit Industries has a great set of instructions for installing Fedora Pi on the RPZ, and you can install pretty much any OS that runs on the ARMv6 chip, but the Raspbian Jessie release on the Raspberry Pi website is the most stable and easy-to-use distribution available for the RPZ. For this cookbook, we will use Raspbian Jessie.

How to do it...

On the Raspberry Pi website, the Downloads page offers both a full version (offline install) and a "Lite" (network install) version of the images. Select the full version when setting up the Raspberry Pi Zero, as you will not have network connectivity right away to download the parts missing from the Lite version. Once you have the full version installed, it is easy to get networking configured and everything updated, which we will cover later in the book. Download the latest full version of NOOBS from the Raspberry Pi website, and unzip it to a new directory. After the extraction is complete, you are ready to move on to the next recipe to install NOOBS on your SD card.

Just click on Download ZIP from a browser, and it will automatically begin:

The NOOBS download and SHA-1 signature

Writing to an SD card with NOOBS

New Out Of Box Software (NOOBS) is the easiest way to get started with any Raspberry Pi. All you need is a formatted SD card, ideally 4 GB or larger. The SD Association website has a formatter tool for Windows and Mac users to clean the card. Always ensure you are formatting the right card.

Getting ready

This is where you'll need your SD card. A 4-GB card is the minimum, but as card prices have dropped a lot over the years, I'd recommend an 8-GB or 16-GB card. I also always recommend hackers to get a couple of cards (for example, get two 8-GB cards instead of one 16-GB card), so you can always have a spare card to write a test operating system to while you have the other SD card in use. If you really get into Raspberry Pi development, you will find having spare SD cards a must.

If you are a Linux user, you should just skip ahead to the Raspbian installation on Ubuntu.

How to do it...

If you are an OS X or Windows user, you can use the SDFormatter utility from the SD Association ( https://www.sdcard.org/downloads/formatter_4/ ) to format your SD card:

The SDFormatter SD card utility

Once your card is formatted, copy the files from your extracted NOOBS download from the last recipe to the newly formatted SD card. Once this is done, you will be ready to finish building your Raspberry Pi Zero.

Once you've downloaded the file, unzip it and copy it to your SD card:

Installing NOOBS is as simple as copying files to a formatted SD card

There's more...

Writing a Raspbian SD card without NOOBS: If you want to skip the NOOBS setup and jump right into Raspbian or if you want to try out a different distribution to see how it works on your Raspberry Pi Zero, there are some great tools available to make this easy to do. First, you need to download the Raspbian image file from the Raspberry Pi website ( https://www.raspberrypi.org/downloads/raspbian/ ). Unzipping the file creates a single, larger file, called the image file. Be sure to download the full file, not the Lite version, as you will be starting without a network connection.

Using Windows to write a Raspbian image to an SD card

In this recipe, you will take a Raspbian image file (.img) and write it directly to an SD card using the free and easy Win32 Disk Imager utility.

How to do it...

On a Windows machine, the Win32 Disk Imager (https://sourceforge.net/projects/win32diskimager/ ) is an easy-to-use open source project for taking image files and writing them to your SD card. Insert your SD card, and select the unzipped image file you downloaded from the Raspberry Pi site:

Win32 Disk Imager for Windows

Once you have verified that you've selected the right .img file and the correct drive letter associated with your SD card, click on Write and wait for the process to finish. Once it completes successfully, eject the card and it will be ready to start your Raspberry Pi Zero.

Using OS X to validate a Raspbian image and write it to an SD card

If you are a Mac user, the process will be a little different from the Windows recipe, but still not too difficult. To do it, we'll leverage OS X's built-in *nix system tools.

Note

Mac OS X used to have a lot of options for easy GUI image writers, but many of them were not updated over time. After Yosemite 10.10.5, the Raspberry Pi community recommends using command-line tools. Fortunately, it is a pretty easy process.

How to do it...

The process for validating and copying a NOOBs installation on OS X is fairly straightforward:

Open a Terminal window in OS X.

Next, run shasum against the downloaded ZIP file to validate the signature:

$ shasum ~/Downloads/2016-05-27-raspbian-jessie.zip 
64c7ed611929ea5178fbb69b5a5f29cc9cc7c157
    /Users/ed/Downloads/2016-05-27-raspbian-jessie.zip

The Raspbian Jessie download and SHA-1 signature

If the return value matches the SHA-1 signature provided on the Raspberry Pi downloads page, your file is good and can be unzipped:
Note
As the downloads change, the SHA-1 will change too, so you'll likely be comparing a different number to your shasum output.
```
$ unzip ~/Downloads/2016-05-27-raspbian-jessie.zip 
Archive:  /Users/ed.snajder/Downloads/2016-05-27-
    raspbian-jessie.zip
inflating: 2016-05-27-raspbian-jessie.img  
```

Next, look at the filesystem before inserting the SD card:

$ df -h
Filesystem      Size   Used  Avail Capacity  iused 
    ifree %iused  Mounted on
/dev/disk1     232Gi  216Gi   16Gi    94% 56751574 
    4163032   93%   /
devfs          205Ki  205Ki    0Bi   100%      710 
    0  100%   /dev
map -hosts       0Bi    0Bi    0Bi   100%        0 
    0  100%   /net
map auto_home    0Bi    0Bi    0Bi   100%        0  
    0  100%   /home
map -fstab       0Bi    0Bi    0Bi   100%        0  
    0  100%   /Network/Servers

Then, insert the SD card and run the command again:

$ df -h
Filesystem      Size   Used  Avail Capacity  iused 
    ifree %iused  Mounted on
/dev/disk1     232Gi  216Gi   16Gi    94% 56751576 
    4163030   93%   /
devfs          211Ki  211Ki    0Bi   100%      730 
    0  100%   /dev
map -hosts       0Bi    0Bi    0Bi   100%        0  
    0  100%   /net
map auto_home    0Bi    0Bi    0Bi   100%        0 
    0  100%   /home
map -fstab       0Bi    0Bi    0Bi   100%        0 
    0  100%   /Network/Servers

/dev/disk2s6    63Mi   20Mi   43Mi    32%      512 
      0  100%   /Volumes/boot


/dev/disk2s1   1.1Gi  1.0Gi   92Mi    92%        0 
      0  100%   /Volumes/RECOVERY

As you can see, /dev/disk2s6 and /dev/disk2s1 were added. This creates two partitions on disk2 - most SD cards will only have one, but however many there are mounted, you need to unmount them with diskutil:
```
$ sudo diskutil unmount /dev/disk2s1
Password:
Volume RECOVERY on disk2s1 unmounted
$ sudo diskutil unmount /dev/disk2s6
Volume boot on disk2s6 unmounted
```
Note
Very important: Running dd on the wrong device will be disastrous - use with extreme caution!
There is a critical difference now from typical Linux drives and dd use. Let's say you had the aforementioned configuration and see that the SD card disk is disk2. For the dd command, you will change this to rdisk2:
```
$ sudo dd bs=1m if=./2016-05-27-raspbian-jessie.img 
    of=/dev/rdisk2

3833+0 records in
3833+0 records out
4019191808 bytes transferred in 377.097088 secs (10658241 bytes/sec)
```
Note
The dd command can take a while to run, and doesn't provide any output while it is, so you can get that feeling it might be stuck. Be patient, depending on the speed of your SD Card it could take several minutes to copy. Newer versions of dd (on Ubuntu 16.04 and newer) include the status=progress flag, which will indicate copying progress.

Finally, eject the disk, and you are ready to go!

$ sudo diskutil eject /dev/rdisk2
Disk /dev/rdisk2 ejected

Using Ubuntu 16.04 to validate a Raspbian image and write it to an SD card

If you are using Ubuntu 12.04 or earlier, the Ubuntu ImageWriter is a GUI tool that makes the installation very easy. If you are using a newer version, usb-imagewriter is not available, but SD cards can still be created from the command line. This will generally work on most flavors of Linux; check with your project's documentation to see the recommended method.

How to do it...

I find the easiest method is to look at what is mounted. If the SD card is inserted, it should be automatically recognized:
```
$ mount -l
```
Another way to find the mount(s) on the SD card is looking using the dmseg command. Ubuntu's documentation recommends using dmesg to find out which device the SD card is. Insert the SD card and run this:
```
$ dmesg | tail -20
```
You'll get a response similar to this:

dmesg output after SD card insertion
Before overwriting, you need to detach the disks that are mounted. In this case, sdd1 and sdd2 are the mounted partitions for device sdd, as shown in the last line of the image above.
In Linux, your disk devices are usually identified by looking in the /dev/ folder for devices starting with sd (for example sda, sdb, sdc). A partition is a division of the physical volume so it can be treated as different devices, and they can be identified by having incremental numbers (for example sdd has partitions sdd1 and sdd2):
```
$ sudo umount /dev/sdd1
$ sudo umount /dev/sdd2
```

After downloading the latest ZIP file of the Raspbian image from the Raspberry Pi website, you can validate it using the sha1sum tool:

$ sudo sha1sum ~/Downloads/2016-05-27-raspbian-
    jessie.zip
64c7ed611929ea5178fbb69b5a5f29cc9cc7c157
   /media/sf_Downloads/2016-05-27-raspbian-jessie.zip

If your return value matches the SHA-1 value on the Raspberry Pi Downloads page, unzip the file, and run the dd command to write your image to the SD card. Make sure you are using the correct device!
The dd command is for entire disks, so we reference sdd instead of the partitions sdd1 or sdd2. We don't want to duplicate things to partitions, we want to duplicate the entire disk, and whatever partitions your source has will be applied to the destination, our SD card.$ sudo dd bs=1M if=/path/to/raspbian-jessie.img of=/dev/sdd

Note

The dd command can take a while to run, and doesn't provide any output while it is, so you can get that feeling it might be stuck. Be patient, depending on the speed of your SD Card it could take several minutes to copy.

The output will be similar to this:

dd command input and output

After several minutes, your card will be ready to go!

Whichever way you decided to set up your SD card, you are just a few connections away from getting your Raspberry Pi Zero online!

Identifying RCA solder points for analog video connections

Let's say you don't have HDMI or need to output video to a device that only accepts the older RCA video connections. With a little bit of soldering, this is very easy! On the Raspberry Pi, you will see two pins marked RCA. By attaching this to a standard RCA plug, you can output your video through this instead of (or even in addition to) the HDMI output.

Getting ready

If you just want to get started with HDMI, this is not a required recipe, and you can skip ahead. You will need:

A soldering iron
An RCA video connector
Connections that can be soldered from the cable to the connector
The board itself

How to do it...

The TV pins in the figure are the connections you can use to connect RCA video to the Raspberry Pi:

Raspberry Pi Zero RCA video

Note
"RCA Video" is technically referred to as Composite Video, and the connectors are typically yellow.
Solder wires or connectors here that will connect to the RCA video plug.

Adding a USB extension over a USB OTG connector

OTG is an adapter connection that allows some devices' USB connections to work as hosts. On the Raspberry Pi Zero, we can use a USB OTG adapter to connect any USB device, whether it's a webcam, keyboard, or printer.

Getting ready

You will need a micro-USB OTG adapter. One end is the male micro-USB to connect to the Raspberry Pi Zero, and the other end is the female standard USB to connect devices (such as mice or keyboards). You'll also want a powered USB hub.

A typical USB OTG adapter will look like this:

Micro-USB OTG adapter

How to do it...

A USB OTG cable is really a must-have when starting out with the RPZ. It converts the micro-USB male connections to a standard USB female connection. With that and a powered USB hub, you will have no problem connecting a keyboard, mouse, USB storage, or devices such as Wi-Fi or Bluetooth. We will look at different ways of implementing more low-profile things such as Wi-Fi later, but a hub is the easiest way to get started.

All you need to do here is connect your OTG adapter to your Raspberry Pi Zero, and then, your powered USB hub to the other end of the OTG adapter. On your hub, connect your keyboard and mouse. Before too long, we will have the hub filled with peripherals, and then we will look at better ways to access (and accessorize!) the Raspberry Pi Zero.

Connecting to displays and changing the configuration settings

The Raspberry Pi Zero is as capable as its predecessors, offering full HDMI video output. The ports are miniaturized, but that doesn't stop you from connecting your Zero to an LCD monitor. Here's how!

Getting ready

Now that you have your USB set up, your final step is getting video output. If you went with the video RCA hack, you can use the HDMI port or RCA video to get going. For HDMI, you'll need a micro-HDMI to standard HDMI adapter (and standard HDMI cable), or an HDMI cable that has one end micro and the other end standard.

A typical standard-to-micro HDMI adapter looks like this:

Standard-to-micro HDMI adapter

We now have our HDMI adapter and cable connected, the SD card installed, and the USB OTG adapter ready to go:

Pi connected to USB OTG and HDMI

How to do it...

Confirm that the SD card is inserted and that your video and USB connections are set, and connect the micro-USB power to an adapter. If you started with NOOBS, you will be taken to the OS selection screen. Right now, there isn't very much to select from. The primary reason is that the Raspberry Pi Zero doesn't yet have Internet capability, so a list of available operating systems cannot be retrieved. For now, it is as easy as clicking on the checkbox for Raspbian and the Install button in the top left. From there, you are a few minutes from your new Raspberry Pi Zero desktop!
Once you click on Install, NOOBS takes care of the rest and sets up a brand new default Raspbian system on your SD card. The system will start quickly and take you right to the installation screen:

NOOBS OS selection screen
When you select Install, NOOBS will take care of the rest and prepare your card with the Raspbian operating system:

NOOBS Raspbian setup
After this is complete, the installer will have you click to reboot, after which you will be taken right into Raspbian.
Note
If you started by using a Raspbian image instead of NOOBS, you will jump right into Raspbian Linux, skipping over the NOOBS setup section.

Initial Pi configuration

The first thing you want to jump into is initial configuration. The fastest way to start that is by opening a terminal window. That's the little computer screen icon three icons to the right of the Menu button:

The Terminal icon is just to the right of the File Cabinet

Click on that and type this command:
```
          sudo raspi-config
```
The Terminal screen - you'll be here a lot
If you are prompted for a password, the initial password for user pi is raspberry. The Raspberry Pi configuration tool contains several options:

raspi-config main options
Let's start with option 1, Expand Filesystem. This will extend all of the space that is available on the SD card after making the image. After you select it, the screen will move back to the terminal, run some more commands, and come back to the configuration utility with a report:

Partition resize success
Next, let's change the default password of the pi user. Select the second option, and you will be prompted to enter and verify a new password.
Note
It is a very smart move to change the default user for pi or deactivate that user entirely. As you start playing with your Pi and making it more accessible to the Internet, you also make it more susceptible to hackers and bots. Since everyone knows the default login and password to a Raspbian installation, leaving them as the default when having them open to the Internet will almost certainly lead to unauthorized access and your work being stolen, altered, or destroyed.

Another good option to take care of right away are Internationalization options. You can set your local time zone and keyboard type in this section. You'll know right away whether your Pi is set to the wrong keyboard layout when you start trying special characters.
Finally, before rebooting, let's go into Advanced Options and pick the fourth option, SSH. Enable the SSH server. This will allow you to use the Raspberry Pi Zero from any computer on the network, once you get it on the network:

Advanced options menu

The table below shows the options available in raspi-config and what they are used for:

Number	Raspi-config option	Function	Notes
1	Expand Filesystem	Extends all available space on the SD card	Run after initial boot
2	Change User PW	Changes the password for the `pi` user	Run after initial boot
3	Boot Options	Gives you different options to boot to desktop, with or without login	Covered in the next section
4	Wait for Network @ Boot	Waits to boot the Pi until a network has become available	Recommend keeping set to No
5	Internationalization Options	Settings for locale, time zone, and keyboard	Run after initial boot
6	Enable Camera	Enables the camera port on the Raspberry Pi	Enable if you have a camera
7	Add to Rastrack	Adds your Raspberry Pi to the Rastrack database	Optional, register at http://rastrack.co.uk
8	Overclock	Increase the maximum speed of the processor	Covered in next section; sadly doesn't work on the Zero
9	Advanced Options	Several different advanced configuration options	Enable SSH after initial boot.
0	About raspi-config	Information about the configuration utility