Hardware Reference
In-Depth Information
Boot Diagnostics
The most common cause for a Pi to fail to boot is a problem with the SD card. Unlike a desk-
top or laptop computer, the Pi relies on files stored on the SD card for everything. If Pi can't
talk to the card, it won't display anything on the screen or show any signs of life at all.
If your Pi's power light glows when you connect the micro-USB power supply, but nothing
else happens and the OK light remains dark, you have an SD card problem. First, ensure that
the card works when you connect it to a PC, and that it shows the partitions and files
expected of a well-flashed card. (For more details, see Chapter 3, “Linux System
Administration”, particularly the section titled “File System Layout” in that chapter.)
If the card works on a PC but not in the Pi, it may be a compatibility problem. Some SD
cards—especially high-speed cards marked as
Class 10
on their labelling—don't operate cor-
rectly when connected to the Pi's onboard SD card reader. A list of cards known to be com-
patible with the Pi can be found on the eLinux wiki at
http://elinux.org/RPi_SD_cards
.
Sadly, if you have an incompatible card, you will probably need to replace it with a different
card in order for the Pi to work. As the Pi's software base is developed, however, work is
being carried out to ensure that a wider range of cards operate correctly with the Pi. Before
giving up on a high-speed card completely, check to see if an updated version of your chosen
Linux distribution is available. (See Chapter 1, “Meet the Raspberry Pi”, for more informa-
tion about distributions.)
If you've been changing the speed of your Raspberry Pi by overclocking (see Chapter 6, “The
Raspberry Pi Software Configuration Tool”), this can also stop it from booting correctly. To
temporarily disable the overclock and run the Pi at its default speed, hold down the Shift key
as you turn the Pi on.
Network Diagnostics
The most useful tool for diagnosing network problems is
ifconfig
. If you're using a wire-
less network connection, jump to Chapter 5, “Network Configuration”, for information on a
similar tool for those devices. Otherwise, read on.
Designed to provide information on connected network ports,
ifconfig
is a powerful tool
for controlling and configuring the Pi's network ports. For its most basic usage, simply type
the tool's name in the terminal:
ifconfig
