GUF-Yocto-jethro-9.0-r7707-0
i.MX6
User Manual
root@santaro:~# cat /sys/class/hwmon/hwmon0/temp1_max_alarm
1
6.14
Touchscreen
The touchscreen device is used by the application framework (e.g. Qt) via the
Linux input subsystem
kernel
API, i.e. its device node
/dev/input/event0
.
For resistive touchscreens, which require a calibration, the
tslib
library is used as an inter-layer. Garz & Fricke
provides optimized signal filtering for the touchscreens that are shipped with their products by choosing a suitable
set of filters with suitable parameters in tslib. The filter configuration can be altered in the configuration file
/etc/ts.conf
in the target’s root filesystem. This should only be done if the user is familar with tslib’s filter system
and the properties and characteristics of its filters. It is also important to reboot the system properly after altering
this configuartion file or executing the
sync
command. Otherwise, the changes may get lost during a hard reset.
6.15
Audio
Garz & Fricke systems with an integrated audio codec make use of ALSA (Advanced Linux Sound Architecture)
as a software interface. This project includes a user-space library (alsa-lib) and a set of tools (aplay, arecord,
amixer, alsactl) for controlling and accessing the audio hardware from user applications or the console. Please
refer to the official ALSA webpage for a full documentation:
For a quick start here are three short examples of how to play/record an audio file and how to adjust the playback
volume.
Example 1:
Play the audio file
my_audio_file.wav
from the console using
aplay
:
root@santaro:~# aplay my_audio_file.wav
Example 2:
Record the audio file
my_recorded_audio_file.wav
from the console using
arecord
:
root@santaro:~# arecord -f cd -t wav > my_recorded_audio_file.wav
Example 3:
Set the playback volume to half of the maximum:
root@santaro:~# amixer sset 'PCM' 50%
The
amixer
command can be used for several settings regarding the audio hardware. Called without parameters,
it gives a list of all available settings along with their possible values.
ALSA is also used in conjuction with playing multimedia files with GStreamer via the
alsasink
plugin after decod-
ing the audio data from an audio stream.
Example 4:
Play a sine signal with a frequency of 440 Hz (default settings) with GStreamer’s
adiotestsrc
and
alsasink
plugins:
root@santaro:~# gst-launch audiotestsrc ! audioconvert ! alsasink
6.16
SRAM
The battery-backed SRAM is controlled by the MTD subsystem in the Linux kernel. Therefore, it can be handled
like a typical MTD device via the device handles
/dev/mtdX
and
/dev/mtdblockX
, where
X
is the logical number
of the device. This number can be found by executing:
root@santaro:~# cat /proc/mtd | grep SRAM
44
