Difference between revisions of "Raspberry Pi"

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[[Category:Getting and installing Arch]]
 
[[Category:Getting and installing Arch]]
{{Note|Support for the ARM architecture is provided on http://archlinuxarm.org/ }}
+
{{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}}
  
How mature is Raspberry Pi (RPI). A brief overview.
+
[http://elinux.org/RPiconfig RPi Config] - Excellent source of info relating to under-the-hood tweaks.
  
== What is Raspberry Pi ==
+
[http://elinux.org/RPI_vcgencmd_usage RPi vcgencmd usage] - Overview of firmware command vcgencmd.
 +
{{Article summary end}}
  
It is a minimalist computer built for ARMv6 architecture. [http://www.raspberrypi.org/ More information about this project] and [http://uk.farnell.com/raspberry-pi technical specification].
+
== Article Preface ==
 +
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.
 +
 
 +
{{Note|Support for the ARM architecture is provided on http://archlinuxarm.org not through posts to the official Arch Linux Forum.  Any posts related to ARM specific issues will be promptly closed per the [https://wiki.archlinux.org/index.php/Forum_Etiquette#Arch_Linux_Distribution_Support_ONLY Arch_Linux_Distrubution_Support_ONLY] policy.}}
  
 
== Installing Arch Linux ARM ==
 
== Installing Arch Linux ARM ==
Line 12: Line 19:
 
See the [http://archlinuxarm.org/platforms/armv6/raspberry-pi#qt-platform_tabs-ui-tabs2 archlinuxarm documentation].
 
See the [http://archlinuxarm.org/platforms/armv6/raspberry-pi#qt-platform_tabs-ui-tabs2 archlinuxarm documentation].
  
== Video ==
+
== Audio ==
 +
{{Note| The requisite module '''snd-bcm2835''' should be autoloaded by default.}}
  
The generic {{pkg|xf86-video-fbdev}} driver can be used.
+
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:
 +
hdmi_drive=2
 +
 
 +
== 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 on the BCM2835 SoC (CPU/GPU):
 +
 
 +
/opt/vc/bin/vcgencmd measure_temp
 +
temp=49.8'C
 +
 
 +
Alternatively, simply read from the filesystem:
 +
% cat /sys/class/thermal/thermal_zone0/temp               
 +
49768
 +
 
 +
=== 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:
 +
 +
arm_freq=800
 +
arm_freq_min=100
 +
core_freq=300
 +
core_freq_min=75
 +
sdram_freq=400
 +
over_voltage=0
 +
 
 +
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 ==
 
== Serial Console ==
Line 20: Line 83:
  
 
Change loglevel to 5 to see boot messages
 
Change loglevel to 5 to see boot messages
  # loglevel=5
+
  loglevel=5
  
Change speed from 115200 to 384000
+
Change speed from 115200 to 38400
  # console=ttyAMA0,384000 kgdboc=ttyAMA0,384000
+
  console=ttyAMA0,38400 kgdboc=ttyAMA0,38400
  
 
Start getty service
 
Start getty service
  # systemctl start getty@ttyAMA0
+
  systemctl start getty@ttyAMA0
  
 
Enable on boot
 
Enable on boot
  # systemctl enable getty@ttyAMA0.service
+
  systemctl enable getty@ttyAMA0.service
  
 
Creating the proper service link:
 
Creating the proper service link:
  # ln -s /usr/lib/systemd/system/getty@.service /etc/systemd/system/getty.target.wants/getty@ttyAMA0.service
+
  ln -s /usr/lib/systemd/system/getty@.service /etc/systemd/system/getty.target.wants/getty@ttyAMA0.service
  
 
Then connect :)
 
Then connect :)
  # screen /dev/ttyUSB0 384000
+
  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
 +
#overscan_left=16
 +
overscan_right=8
 +
overscan_top=-16
 +
overscan_bottom=-16
 +
 
 +
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.
  
Referenced from these [http://www.raspberrypi.org/phpBB3/viewtopic.php?f=53&t=19186] posts [https://bbs.archlinux.org/viewtopic.php?id=144847]
+
A reboot is needed for new settings to take effect.

Revision as of 11:08, 10 April 2013

Template:Article summary start Template:Article summary text Template:Article summary heading Template:Article summary wiki

RPi Config - Excellent source of info relating to under-the-hood tweaks.

RPi vcgencmd usage - Overview of firmware command vcgencmd. Template:Article summary end

Article Preface

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.

Note: Support for the ARM architecture is provided on http://archlinuxarm.org not through posts to the official Arch Linux Forum. Any posts related to ARM specific issues will be promptly closed per the Arch_Linux_Distrubution_Support_ONLY policy.

Installing Arch Linux ARM

See the 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 /boot/config.txt to force audio over HDMI:

hdmi_drive=2

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 on the BCM2835 SoC (CPU/GPU):

/opt/vc/bin/vcgencmd measure_temp
temp=49.8'C

Alternatively, simply read from the filesystem:

% cat /sys/class/thermal/thermal_zone0/temp                
49768

Voltage

Four different voltages can be monitored via /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 /boot/config.txt, for example:

arm_freq=800
arm_freq_min=100
core_freq=300
core_freq_min=75
sdram_freq=400
over_voltage=0

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 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

loglevel=5

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 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
#overscan_left=16
overscan_right=8
overscan_top=-16
overscan_bottom=-16

Users wishing to use the analog video out should consult this config file which contains options for non-NTSC outputs.

A reboot is needed for new settings to take effect.