topic LCD turning white after a few minutes in i.MX Processors

LCD turning white after a few minutes

erezsteinberg — Sat, 08 Nov 2014 19:42:30 GMT

Hi all-

I have some strange behavior on my board and LCD

It's a custom iMX6S board running Linux 3.0.35. The display is a parallel LCD (8-bit) using BT656 protocol.

After booting, I display an image on the LCD. After a few minutes the display suddenly becomes white. At that point, if I try to display a new image nothing happens.

However, if I do "echo 0 > /sys/devices/platform/mxc_sdc_fb.0/graphics/fb0/blank", then I can display images again. But, again, after a few minutes the LCD turns white.

Any ideas what might be causing the LCD to 'turn white' by itself?

Sincerely,

Erez

Re: LCD turning white after a few minutes

igorpadykov — Sun, 09 Nov 2014 10:13:36 GMT

Hi Erez

one can try to turn off LCD blanking also with

echo -e "\033[9;0]" > /dev/tty0

https://community.freescale.com/message/432351#432351

Best regards

igor

Re: LCD turning white after a few minutes

erezsteinberg — Sun, 09 Nov 2014 14:48:51 GMT

Hi Igor,

Thanks -- that solved the issue.

I found this resource with additional useful commands --- http://www.armadeus.com/wiki/index.php?title=FrameBuffer

For anyone looking::

To stop blinking cursor:

# echo 0 > /sys/class/graphics/fbcon/cursor_blink

also possible at boot time (with 3.x recent kernels):

BIOS> setenv extrabootargs vt.global_cursor_default=0

To make it blinking again:

 # echo 1 > /sys/class/graphics/fbcon/cursor_blink

To grab a screenshot of a running Framebuffer application, use FBGrab
To enter in Framebuffer sleep mode:

# echo 1 > /sys/class/graphics/fb0/blank

To leave Framebuffer sleep power mode:

 # echo 0 > /sys/class/graphics/fb0/blank

To set "sleep mode"/screensaver entering time (where X is a time in minute; 0 = never):

# echo -e '\033[9;X]' > /dev/tty1 (from serial console)

 # echo -e '\033[9;X]'    (from framebuffer console)

or to set it at each boot, use /etc/inittab:

 tty1::sysinit:echo -e '\033[9;X]'

Other usefull ESC sequences

To (definitly) hide cursor:

 # echo -e '\033[?17;0;0c' > /dev/tty1    (from serial console)

 # echo -e '\033[?17;0;0c'    (from framebuffer console)

inverse screen on:

# echo -e '\033[?5h' > /dev/tty1

inverse screen off:

 # echo -e '\033[?5l' > /dev/tty1

Regards,

Erez