ADC reading is -1

Hi all,
I am working with a mini2440 based robot.
I have interfaced 4 analog sensors with my 4 ADC channels.
These were working fine till about a few days back. But now the adc
channels are giving a problem. The read value always seems to be -1.
When i try "cat /dev/adc" or "cat /dev/adc1", etc i keep seeing a value -1.

What does this mean? I checked mt sensors and they are fine. Does it mean
that the ADC port has burnt up?

Please help
Thanks in advance
Chinmay

PS: the touch screen is also not working. It is blank no matter how i boot.

Chinmay

What is the max voltage that the sensors can source?

Have the same problem but my ADC started to give a problem after some time
of working. Suddenly it started to give -1 and touchscreen wasn't
responding. When I disconnected my sensor, and killed program that was
reading from that sensor - touchscreen started to work. Maybe any ideas?

thanks in advance
best regards
Tom

YES, i have some probleman, READING (-1)

any idea?

To make the analogue channels working in combination with the touch a state
machine is required, because there is only one real ADC for all input
channels. Maybe the driver is broken.

do you know how fix it?

Using a working driver. Sorry, there is no information about the kernel you
are using, no links to sources, no configuration you are using to build the
kernel and to configure runtime. How should I help you? In my kernel I can
use the touch and the other ADC channels. You can find it here:
http://www.oselas.org/oselas/bsp/pengutronix/mini2440_bsp_en.html

i use (Linux 2.6.32.2 2011-03-05) from friendlyarm. if you can help me.

So, you are using a binary distribution? Or did you compile your kernel by
yourself?

i compile my kernel

Okay, why not starting with a more current kernel (say 2.6.38) and adding a
few missing patches to make the ADC work? Are you experienced with kernel
patching? If yes, try googeling around for Marek's patches. Or use the
patch stack from my board support package mentioned in
http://www.friendlyarm.net/forum/topic/2779. When you extract the
repository, you will find the patch stack in
"configs/platform-friendlyarm-mini2440/patches/linux-2.6.38"