Difference between revisions of "Raspberry Pi"

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[[Category:Getting and installing Arch]]
#REDIRECT: [[:Category:ARM architecture]]
{{Article summary start}}
{{Article summary text|Raspberry Pi is a minimalist computer built for the [[Wikipedia:ARMv6|ARMv6 architecture]]. [http://www.raspberrypi.org/ More information about this project] and [http://uk.farnell.com/raspberry-pi technical specification].}}
{{Article summary heading|Related}}
{{Article summary wiki|Beginners%27_Guide}} - This article is not meant to be an exhaustive setup guide and assumes that the reader has setup an Arch system before. Arch newbies are encouraged to read the Beginners'_Guide if unsure how to preform standard tasks such as creating users, managing the system, etc.
[http://elinux.org/RPiconfig RPi Config] - Excellent source of info relating to under-the-hood tweaks.
[http://elinux.org/RPI_vcgencmd_usage RPi vcgencmd usage] - Overview of firmware command vcgencmd.
{{Article summary end}}
== Article Preface ==
{{Note|Support for the ARM architecture is provided on http://archlinuxarm.org/ }}
{{Note|Posts to the official Arch Linux Forum related to ARM specific issues will be promptly closed.}}
== Installing Arch Linux ARM ==
See the [http://archlinuxarm.org/platforms/armv6/raspberry-pi#qt-platform_tabs-ui-tabs2 archlinuxarm documentation].
== Audio ==
{{Note| The requisite module '''snd-bcm2835''' should be autoloaded by default.}}
Install the needed packages:
pacman -S alsa-utils alsa-firmware alsa-lib alsa-plugins
Optionally adjust the default volume using `alsamixer` and ensure that the sole source "PCM" is not muted (denoted by double MM if muted).
Select an audio source for output:
amixer cset numid=3 x
Where 'x' corresponds to:
*0 for Auto
*1 for Headphones
*3 for HDMI
=== Caveats for HDMI Audio ===
Some applications require a setting in {{ic|/boot/config.txt}} to force audio over HDMI:
== Onboard Hardware Sensors ==
=== Temperature ===
Temperatures sensors for the board itself are including as part of the '''raspberrypi-firmware-tools''' package.  the RPi offers a sensor of the BCM2835 SoC (CPU/GPU):
/opt/vc/bin/vcgencmd measure_temp
Alternatively, simply read from the filesystem:
% cat /sys/class/thermal/thermal_zone0/temp               
=== Voltage ===
Four different voltages can be monitored via {{ic|/opt/vc/bin/vcgencmd}} as well:
% /opt/vc/bin/vcgencmd measure_volts <id>
*core for core voltage
*sdram_c for sdram Core voltage
*sdram_i for sdram I/O voltage
*sdram_p for sdram PHY voltage
== Overclocking/Underclocking ==
The Raspberry Pi can be overclocked by editing {{ic|/boot/config.txt}}, for example:
The optional xxx_min lines define the min usage of their respective settings.  When the system is not under load, the values will drop down to those specified.  Consult the [[http://elinux.org/RPiconfig#Overclocking Overclocking]] article on elinux for additional options and examples.
A reboot is needed for new settings to take effect.
{{Note|The overclocked setting for CPU clock applies only when the governor throttles up the CPU, i.e. under load.}}
Users may query the current frequency of the CPU via this command:
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
== Serial Console ==
Edit the default /boot/cmdline.txt
Change loglevel to 5 to see boot messages
Change speed from 115200 to 38400
console=ttyAMA0,38400 kgdboc=ttyAMA0,38400
Start getty service
systemctl start getty@ttyAMA0
Enable on boot
systemctl enable getty@ttyAMA0.service
Creating the proper service link:
ln -s /usr/lib/systemd/system/getty@.service /etc/systemd/system/getty.target.wants/getty@ttyAMA0.service
Then connect :)
screen /dev/ttyUSB0 38400
== Video ==
pacman -S xf86-video-fbdev
Adjustments are likely required to correct proper overscan/underscan and are easily achieved in {{ic|boot/config.txt}} in which many tweaks are set.  To fix, simply uncomment the corresponding lines and setup per the commented instructions:
# uncomment the following to adjust overscan. Use positive numbers if console
# goes off screen, and negative if there is too much border
Users wishing to use the analog video out should consult [https://raw.github.com/Evilpaul/RPi-config/master/config.txt this] config file which contains options for non-NTSC outputs.
A reboot is needed for new settings to take effect.

Latest revision as of 01:12, 15 December 2017