how to use adc mini2440??

Forum: Linux
Thepascalix 
Hi  for everyone. I have a serious problem with my mini2440. I want to use
the pin AIN1, AIN2, AIN3 (this is the pin of ADC) but i'm not able to
ability in kernel. I try to include in kernel configuration but without
response... 
How i make to use it?? Can you help me to enable it??. Thanks a lot for
yourdisponition

linux_support 
Hi
The kernel only contains the driver for AIN0. If you want to use the pins
AIN1,AIN2 and AIN3 then you will have to make your own drivers and then
insert them into the kernel either as modules or else you can include them
in the kernel , recompile the kernel and transfer the image in mini2440.

Regards
Vector Institute
Specialised in Embedded Systems
linuxsupport@vectorindia.org
http://www.vectorindia.org

Juergen Beisert 
With a few adaptions a recent 2.6.39 supports all ADC channels. You need
the "Hardware Monitoring support", "<*>   Samsung built-in ADC" and a small
adaption in the platform file to register the ADC unit at runtime.

thepascalix 
Juergen Beisert

hi, thanks for your response ;)

what are this adaptation on kernel?? I try the adaptation described in
precedent post, but don't works...

Juergen Beisert 
You have to modify the Mini2440 platform file in the kernel to register the
"s3c_device_hwmon" device at run-time. Then the ADC driver occurs at
run-time and you can access the channels.

Nick 
hi everyone.
hi,Juergen Beisert

I have a problem. 
I test adc with AIN0, and it used to work very well. So, i connect it with
my analog signal.
it work well. but now, it always show 1022 and 1023 on screen although i
remove my signal.  I don't know maybe my "adc hardware" it error.
I try setup Android OS again, but it not change.
is "adc hardware" error.
please, give me advice.

Juergen Beisert 
Read the schematics of the Mini2440. AIN0 is controlled via W1 on your
board.

Nick 
hi Juergen Beisert.
yes. AIN0 is controlled by via W1, so I removed it, and replace it with my
signal. It still worked, but now it always show value 1022 and 1023
although I place via W1 back. It not effect.
I thinks. i will try with AIN1 but I don't know build kernel.

davef 
What is the maximum DC voltage that your analog signal can go to?

I wouldn't try AIN1 or may have two ports that don't work!  Its a good idea
to have some form of protection, but that's another story.

Nick 
hi davef
my signal is small, maybe less 3.3v.
I think, maybe it by my code, b/c i read it continuously.
  for(i = 0; i<20; i++){
             k =HardwareControler.readADC();
       WEIGHTreceive.append(" " + String.valueOf(k));
  }      
It still work sometime, but not now.

NothinRandom 
davef,

In this pdf, http://www.armkits.com/download/s3c2440.pdf, on page 27-2. It
states that the analog signal should not exceed 3.6V.