mirror of
https://github.com/archlinuxarm/wiki.git
synced 2024-11-18 22:53:58 +00:00
Jason Ryan
Kevin Mihelich
parent
171c42d5a9
commit
11db38c5f7
1 changed files with 227 additions and 0 deletions
227
Raspberry_Pi.md
Normal file
227
Raspberry_Pi.md
Normal file
|
|
@ -0,0 +1,227 @@
|
|||
## Audio
|
||||
`alsa-utils` should supply the needed programs to use onboard sound. Default
|
||||
volume can be adjusted using alsamixer.
|
||||
|
||||
A key change with Linux kernel version 4.4.x for ARM related to ALSA and to the
|
||||
needed sound module: in order to use tools such as alsamixer with the current
|
||||
kernel, users must modify `/boot/config.txt` to contain the following line:
|
||||
|
||||
dtparam=audio=on
|
||||
|
||||
### Caveats for Audio
|
||||
To force audio over HDMI, add this to `/boot/config.txt`:
|
||||
|
||||
hdmi_drive=2
|
||||
|
||||
If you experience distortion using the 3.5mm analogue output:
|
||||
|
||||
audio_pwm_mode=2
|
||||
|
||||
## Video
|
||||
The X.org driver for Raspberry Pi can be installed with the `xf86-video-fbdev`
|
||||
or `xf86-video-fbturbo-git` package.
|
||||
|
||||
### CPU/GPU RAM split
|
||||
Memory split between the CPU and GPU can be set in `boot/config.txt`
|
||||
by adjusting the parameter `gpu_mem` which stands for the amount of RAM in MB
|
||||
that is available to the GPU (minimum 16, default 64) and the rest is available
|
||||
to the ARM CPU.
|
||||
|
||||
### HDMI/Analogue TV-Out
|
||||
With the default configuration, the Raspberry Pi uses HDMI video if a HDMI
|
||||
monitor is connected. Otherwise, it uses analog TV-Out (also known as composite
|
||||
output or RCA) To turn the HDMI or analog TV-Out on or off, have a look at
|
||||
`/opt/vc/bin/tvservice`
|
||||
|
||||
Use the `-s` parameter to check the status; the `-o`
|
||||
parameter to turn the display off and `-p` parameter to power on HDMI with
|
||||
preferred settings.
|
||||
|
||||
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
|
||||
```
|
||||
|
||||
Or simply disable overscan if the TV/monitor has a "fit to screen" option.
|
||||
|
||||
disable_overscan=1
|
||||
|
||||
Users wishing to use the analog video out should consult [this config file](https://raw.github.com/Evilpaul/RPi-config/master/config.txt)
|
||||
which contains options for non-NTSC outputs.
|
||||
|
||||
## Camera
|
||||
The commands for the camera module are included as part of the raspberrypi-firmware package:
|
||||
```
|
||||
$ /opt/vc/bin/raspistill
|
||||
$ /opt/vc/bin/raspivid
|
||||
```
|
||||
|
||||
Append to `/boot/config.txt`:
|
||||
```
|
||||
gpu_mem=128
|
||||
start_file=start_x.elf
|
||||
fixup_file=fixup_x.dat
|
||||
```
|
||||
Optionally
|
||||
|
||||
disable_camera_led=1
|
||||
|
||||
The following is a common error:
|
||||
|
||||
```
|
||||
mmal: mmal_vc_component_enable: failed to enable component: ENOSPC
|
||||
mmal: camera component couldn't be enabled
|
||||
mmal: main: Failed to create camera component
|
||||
mmal: Failed to run camera app. Please check for firmware updates
|
||||
```
|
||||
|
||||
which can be corrected by setting these values in `/boot/config.txt`:
|
||||
```
|
||||
cma_lwm=
|
||||
cma_hwm=
|
||||
cma_offline_start=
|
||||
```
|
||||
|
||||
Another common error:
|
||||
```
|
||||
mmal: mmal_vc_component_create: failed to create component 'vc.ril.camera' (1:ENOMEM)
|
||||
mmal: mmal_component_create_core: could not create component 'vc.ril.camera' (1)
|
||||
mmal: Failed to create camera component
|
||||
mmal: main: Failed to create camera component
|
||||
mmal: Only 64M of gpu_mem is configured. Try running "sudo raspi-config" and ensure that "memory_split" has a value of 128 or greater
|
||||
```
|
||||
|
||||
can be corrected by adding the following line to `/etc/modprobe.d/blacklist.conf`:
|
||||
|
||||
blacklist i2c_bcm2708
|
||||
|
||||
In order to use standard applications (those that look for `/dev/video0`) the
|
||||
V4L2 driver must be loaded. This can be done automatically at boot by creating
|
||||
an autoload file, `/etc/modules-load.d/rpi-camera.conf`:
|
||||
|
||||
bcm2835-v4l2
|
||||
|
||||
The V4L2 driver by default only allows video recording up to 1280x720, else it
|
||||
glues together consecutive still screens resulting in videos of 4 fps or lower.
|
||||
Adding the following options removes this limitation, `/etc/modprobe.d/rpi-camera.conf`:
|
||||
|
||||
options bcm2835-v4l2 max_video_width=3240 max_video_height=2464
|
||||
|
||||
## Onboard Hardware Sensors
|
||||
### Temperature
|
||||
Temperatures sensors can be queried with utils in the `raspberrypi-firmware` package.
|
||||
|
||||
```
|
||||
$ /opt/vc/bin/vcgencmd measure_temp
|
||||
temp=49.8'C
|
||||
```
|
||||
|
||||
### Voltage
|
||||
Four different voltages can be monitored via `/opt/vc/bin/vcgencmd`:
|
||||
|
||||
$ /opt/vc/bin/vcgencmd measure_volts <id>
|
||||
|
||||
Where `<id>` is:
|
||||
|
||||
* core for core voltage
|
||||
* sdram_c for sdram Core voltage
|
||||
* sdram_i for sdram I/O voltage
|
||||
* sdram_p for sdram PHY voltage
|
||||
|
||||
### Watchdog
|
||||
BCM2708 has a hardware watchdog which can be utilized by enabling the
|
||||
`bcm2708_wdog` kernel module.
|
||||
|
||||
For proper operation the watchdog daemon also has to be installed, configured
|
||||
(by uncommenting the "watchdog-device" line in `/etc/watchdog.conf`) and
|
||||
enabled.
|
||||
|
||||
This should also apply for Raspberry Pi 2 by using the `bcm2709_wdog` module
|
||||
and Raspberry Pi 3 by using the `bcm2835_wdt` module.
|
||||
|
||||
## Hardware Random Number Generator
|
||||
Arch Linux ARM for the Raspberry Pi had the `bcm2708-rng` module set to load at
|
||||
boot; starting with kernel 4.4.7 the `bcm2835_rng` module replaces the
|
||||
former on Raspberry Pi 2 and Raspberry Pi 3 units.
|
||||
|
||||
Install `rng-tools` and
|
||||
tell the Hardware RNG Entropy Gatherer Daemon (`rngd`) where to find the hardware
|
||||
random number generator. This can be done by editing `/etc/conf.d/rngd`:
|
||||
|
||||
RNGD_OPTS="-o /dev/random -r /dev/hwrng"
|
||||
|
||||
and enabling and starting the `rngd` service.
|
||||
|
||||
If `haveged` is running, it should be stopped and disabled, as it might
|
||||
compete with `rngd` and is only preferred when there is no hardware random number
|
||||
generator available.
|
||||
|
||||
Once completed, this change ensures that data from the
|
||||
hardware random number generator is fed into the kernel's entropy pool at
|
||||
`/dev/random`. To check the available entropy, run:
|
||||
|
||||
# cat /proc/sys/kernel/random/entropy_avail
|
||||
|
||||
The number it reports should be around 3000, whereas before setting up rngd it
|
||||
would have been closer to 1000.
|
||||
|
||||
## I/O Pins
|
||||
### GPIO
|
||||
To be able to use the GPIO pins from Python, use the RPi.GPIO library.
|
||||
Install the [python-raspberry-gpio](https://aur.archlinux.org/packages/python-raspberry-gpio/) package
|
||||
from the AUR.
|
||||
|
||||
### SPI
|
||||
To enable the `/dev/spidev*` devices, uncomment the following line in
|
||||
`/boot/config.txt`:
|
||||
|
||||
device_tree_param=spi=on
|
||||
|
||||
### I2C
|
||||
Install `i2c-tools` and `lm_sensors` packages.
|
||||
|
||||
Configure the bootloader to enable the i2c hardware by appending to `/boot/config.txt`:
|
||||
|
||||
dtparam=i2c_arm=on
|
||||
|
||||
Configure the `i2c-dev` and `i2c-bcm2708` (if not blacklisted for the camera) modules to be loaded at boot in
|
||||
`/etc/modules-load.d/raspberrypi.conf`:
|
||||
|
||||
i2c-dev
|
||||
i2c-bcm2708
|
||||
|
||||
Reboot the Raspberry Pi and issue the following command to get the hardware address:
|
||||
|
||||
i2cdetect -y 0
|
||||
|
||||
Note: When using the I2C1 port instead of I2C0, one will need to run `i2cdetect
|
||||
-y 1` instead and replace `i2c-0` with `i2c-1` in the following steps.
|
||||
|
||||
Now instantiate the device. Change the hardware address to the address found in
|
||||
the previous step with '0x' as prefix (e.g. 0x48) and choose a device name:
|
||||
|
||||
echo <devicename> <hardware address> >/sys/class/i2c-adapter/i2c-0/new_device
|
||||
|
||||
Check `dmesg` for a new entry:
|
||||
|
||||
i2c-0: new_device: Instantiated device ds1621 at 0x48
|
||||
|
||||
Finally, read the sensor output:
|
||||
sensors
|
||||
|
||||
## See Also
|
||||
|
||||
* [Raspberry Pi](https://www.raspberrypi.org/) - Official website
|
||||
* [RPi Config](http://elinux.org/RPiconfig) - Excellent source of info relating to under-the-hood tweaks.
|
||||
* [RPi vcgencmd usage](http://elinux.org/RPI_vcgencmd_usage) - Overview of firmware command vcgencmd.
|
||||
* [Arch Linux ARM on Raspberry Pi](http://archpi.dabase.com/) - A FAQ style site with hints and tips for running Arch Linux on the RPi
|
||||
|
||||
Loading…
Reference in a new issue