Raspberry Pi A, User Manual, Page: 127 / 314

C H A P T E R 7
A D V A N C E D R A S P B E R R Y P I C O N F I G U R A T I O N
111
Modifying the Display
Usually, the Raspberry Pi will detect the type of display that’s connected and alter its settings
accordingly. Sometimes, however, this automatic detection doesn’t work. This is often the
case when a Raspberry Pi from one country is connected to an older TV from another coun-
try. If you connect your Pi to your TV and there’s nothing to see, you may need to override
these defaults.
Various settings in the
config.txt
file can be used to improve or alter the video output.
These settings, and their possible values, are described in the following list.
WARNING
Manually adjusting the High Definition Multimedia Interface (HDMI) or composite video output
settings can leave your Pi unable to communicate with your monitor. It’s usually best to use
the automatically detected settings, unless you’re unable to see a picture in the first place.
❍
overscan_left
—This setting moves the picture inwards a set number of pixels to com-
pensate for a TV’s overscan . If the text on the Pi is disappearing off the edge of the screen,
adjusting the overscan will fix it. Values should be given as the number of pixels to skip.
❍
overscan_right
—This setting does the same job as
overscan_left
, but on the
right side of the screen.
❍
overscan_top —Again, this setting ignores a certain number of pixels, but this time
on the top of the screen.
❍
overscan_bottom
—This setting can be used to skip a number of pixels from the bot-
tom of the display. Typically, the values for all the
overscan_
settings would be the
same, creating a regular border around the display.
❍
disable_overscan
—If you use a monitor or TV via HDMI, you may find that your
image has a black border around it. To get rid of this border, any default overscan set-
tings can be disabled by setting this value to
1
.
❍
framebuffer_width
—This value is measured in pixels, and adjusting it will change
the width of the console. If text appears too small on your screen, try changing this to
a lower value than the default width of the connected display.
❍
framebuffer_height
—This setting affects the size of the console in the same way as
framebuffer_width
, but vertically rather than horizontally.
❍
framebuffer_depth —Controls the colour depth of the console in bits per pixel. The
default is 16 bits per pixel, which gives 65,536 colours. Other values, including 8 bits
per pixel (256 colours), 24 bits per pixel (around 16.7 million colours) and 32 bits per
pixel (around 1 billion colours) are valid, but may cause graphical corruption.