Hardware Reference
In-Depth Information
Hardware Settings—config.txt
The Pi's hardware is controlled by settings contained in a file called config.txt , which is located
in the /boot directory (see Figure 7-3). This file tells the Pi how to set up its various inputs and
outputs, and at what speed the BCM2835 chip and its connected memory module should run.
Figure 7-3:
The contents of
the /boot
directory, with
config.txt
highlighted
If you're having problems with graphics output, such as the image not filling the screen or
spilling over the edge, config.txt is where you'll be able to fix it. Normally, the file is
empty or, on some distributions, simply not present; this just means that the Pi will operate
using its pre-set defaults. If you want to make changes and the file isn't there, just create a
new text file called config.txt and fill in the settings you want to change.
he config.txt file can control almost all aspects of the Pi's hardware, with the exception
of the way the central processing unit (CPU) and graphics processing unit (GPU) sections of
the BCM2835 apportion the memory. You'll learn how to alter that split in the “Memory
Partitioning” section, later in this chapter.
he config.txt file is only read when the system first starts up. Any changes made while
the Pi is running won't take effect until the system is restarted, or switched off and back on
again. In the event that the changes are unwanted, simply deleting the file from the /boot
directory should be enough to restore the defaults once more. If the Pi won't boot with your
new settings, just remove the SD card and delete config.txt from the boot partition on
another PC, and then reinsert the card into the Pi and try again.
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