COM AM35 Linux

FAQ

Ethernet does not work

Check if the line "allow-hotplug eth0" in the file "/etc/network/interfaces" is activated. You can activate the ethernet interface on a running system with the command:

ifconfig eth0 up

Remark: To work with a nfs-rootfilesystem you have to disable the line "allow-hotplug eth0" in the file "/etc/network/interfaces". Maybe the system was prepared for this method for development and nobody did change it back.

How to set a Linux environment variable?

This example shows you how to configure the system to use a proxy-server with a environment variable.

export http_proxy=http://192.168.xxx.xxx:xxxx

How to schedule jobs to run periodically at certain times or dates?

You can use the cron daemon and/or anacron. To use anacron you have to copy or link your program or script into one of the the following folders:

/etc/cron.hourly

/etc/cron.daily

/etc/cron.weekly

/etc/cron.monthly

For further information have a look at the general linux documentation.

Debian system

How to create a microSD-card with a rootfilesystem on it

1. Format a microSD card like following (in linux e.g. you can use palimpsest) with Master Boot Record partition scheme

P1 FAT (Primary partition: 100MB)

P2 ext3 (Primary partition: Residual space)

2. Untar the root file system to the ext3 partition of the microSD card (Don't copy the tar archive directly to the microSD card)

Start the Console on Linux

su

chmod 755 /path/of/the/microSD_card

cd /path/of/the/microSD_card

tar xfjv path/to/RootFS/Name_of_RootFS_file.tar.bz2

Remark: If you got a *.tar.gz file so type tar xfzv ... to extract the rootfilesystem.

Calibrating the touchscreen

ts_calibrate

Check the enviroment variable "TSLIB_TSDEVICE=/dev/input/event0" with printenv if an error occurs.

Running Qt Demos

cd /usr/qt/demos/demoname

demoname -qws

For the Qt-Browser change demoname to browser

If the touchscreen does not work please check the enviroment variable "QWS_MOUSE_PROTO=Tslib:/dev/input/event0" with printenv.

Run Qt demos with powerVR (3d acceleration) support:

cd /usr/qt/demos/embedded/demoname

demoname -qws

Run demos with a usb-mouse as input device:

cd /usr/qt/demos/demoname

/QWS_MOUSE_PROTO=Auto:/dev/input/mice demoname -qws

Remark: Just remember that you need to run the Qt demos with the options -qws. Omitting -qws results in the app waiting to connect to the QWS Server, which is not running.

How to control the display brightness

echo <value> >/sys/class/backlight/omap-pwm-backlight/brightness

value range: 0..255

Login/Shutdown system

Username:	root
Password:	foo

shutdown -h now

How to control the GPIOs

DHCOM Name:	alt. DHCOM Name:	SO-DIMM Pin#	Linux <GPIO#>
GPIO A		154	116
GPIO B		156	117
GPIO C		162	118
GPIO D		163	119
GPIO E		164	125
GPIO F		165	140
GPIO G		167	141
GPIO H		173	155
GPIO I		175	152
CIF HSYNC	GPIO J	74	96
CIF PCLK	GPIO K	72	94
CIF MCLK	GPIO L	70	58
CIF VSYNC	GPIO M	68	97
CIF D9	GPIO N	66	98
CIF D8	GPIO O	64	95
CIF D7	GPIO P	62	106
CIF D6	GPIO Q	60	105
CIF D5	GPIO R	58	104
CIF D4	GPIO S	56	103
CIF D3	GPIO T	54	102
CIF D2	GPIO U	52	101
CIF D1	GPIO V	50	100
CIF D0	GPIO W	48	99

Remark: Depending on your board configuration some of the additional gpios shared with the camera interface are not available on your system.

Export

echo <GPIO#> >/sys/class/gpio/export

Remark: Have a look into /sys/class/gpio/ for already configured gpios.

Set direction

echo in >/sys/class/gpio/gpio<GPIO#>/direction

echo out >/sys/class/gpio/gpio<GPIO#>/direction

Set state

echo 0 >/sys/class/gpio/gpio<GPIO#>/value

echo 1 >/sys/class/gpio/gpio<GPIO#>/value

Initialize and test CAN

Initialize:

ip link set can0 up type can bitrate 500000

Send test message via cansend (part of can-utils):

cansend can0 100#11.2233.44556677.88

Receive can messages (part of can-utils):

candump can0