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If the first partition on an SD card or a USB mass storage device already contains a file system when it is plugged
into the device, it is mounted automatically by the
/media/mmcblk0pX
with X being a positive number, and USB mass storage devices are mounted to mount point
/media/sdXY
with X=a..z and Y being a positive number.
All further partitions or partitions with a newly created file system have to be mounted manually, like shown in the
following examples.
Example 2: Mount the first partition on an SD Card into a newly created directory:
root@vincell:~# mkdir /my_sdcard
root@vincell:~# mount /dev/mmcblk0p1 /my_sdcard
Example 3: Mount the first partition on a USB mass storage device into a newly created directory:
root@vincell:~# mkdir /my_usb_drive
root@vincell:~# mount /dev/sda1 /my_usb_drive
6.12 Temperature Sensor
Most Garz & Fricke systems are equipped with an on-board hardware temperature sensor. The sensor is a Texas
Instruments LM73 connected via I
sysfs file in /sys/class/hwmon/hwmon0/device/.
For example:
root@vincell:~# cat /sys/class/hwmon/hwmon0/device/temp1_input
+38.0
The sensor generates an alert when the measured temperature exceeds the maximum temperature defined in
temp1_max. The alert flag will be set to 0 (active low) and an interrupt is generated. The interrupt will trigger an
event on the
temp1_alrt
sysfs entry, that can be catched using the
Read the temperature alert flag (active low):
root@vincell:~# cat /sys/class/hwmon/hwmon0/device/temp1_alrt
1
To reset the temperature alert flag the currently measured temperature needs to be below the maximum temper-
ature value. Then the flag can be reset by writing 1 to the
Reset the temperature alert flag:
root@vincell:~# echo 1 > /sys/class/hwmon/hwmon0/device/temp1_alrtrst
6.13 Touchscreen
The touchscreen device is used by the application framework (e.g. Qt) via the
API, i.e. its device node /dev/input/event0.
For resistive touchscreens, which require a calibration, the
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
6.14 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,
32
VINCELL
User Manual
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udev
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C. To poll the currently measured temperature you can read the corresponding
sync
command. Otherwise, the changes may get lost during a hard reset.
service. SD card partitions are mounted to mount point
poll()
function.
temp1_alrtrst
sysfs entry.
Linux input subsystem
library is used as an inter-layer. Garz & Fricke
tslib
kernel
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