Hardware Reference
In-Depth Information
Boot Diagnostics
he 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 iles 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 iles
expected of a well-lashed card. (For more details, see Chapter 2, “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 cause
compatibility problems with the Pi can be found on the eLinux wiki:
http://elinux.
org/RPi_VerifiedPeripherals#Problem_SD_Cards
Sadly, if you have one of the cards on the list, you may need to replace it with a diferent card
in order for the Pi to work. As the Pi's software base is developed, however, work is being car-
ried 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 information
about distributions.)
Network Diagnostics
he most useful tool for diagnosing network problems is
ifconfig
. If you're using a wire-
less network connection, jump to Chapter 4, “Network Coniguration”, 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 coniguring the Pi's network ports. For its most basic usage, simply type
the tool's name in the terminal:
ifconfig
Called in this manner,
ifconfig
provides information on all the network ports it can ind
(see Figure 3-2). For the standard Raspberry Pi Model B, there are two ports: the physical
Ethernet port on the right side of the board, and a virtual
loopback
interface that allows pro-
grams on the Pi to talk to each other.
