Hello Mikkel,

"Make sure that you have given the right write permissions to the LED
sysfs entry. This can be done in your init.rc file."

Can you elaborate on this a bit more please? I am trying to edit my init.rc 
file but there are so many sections e.g. on boot.

Where would I insert the commands?

I am assuming I have to insert "write sysfs/gpio/export xxx" or something 
similar.

Thanks
Jerry
On Tuesday, November 23, 2010 at 12:33:19 PM UTC+2, Mikkel Christensen 
wrote:
>
> Hello, 
>
> I would use the SimpleJNI sample application [1] as a base reference. 
> This does the right coupling from Android application to your lower 
> level hardware interface. 
>
> If the LED is already exposed in sysfs you are lucky and it should be 
> quite easy. Otherwise create a Kernel device driver that does the 
> exposure of the LED to sysfs. 
>
> Then in the /jni/native.cpp function do the proper write to the sysfs 
> entry like this (note: this depends on how the led is exposed trough 
> sysfs): 
>
> ret = system("echo 1 > /sys/class/leds/red/brightness"); 
>
> Make sure that you have given the right write permissions to the LED 
> sysfs entry. This can be done in your init.rc file. 
>
> Best regards, 
>  Mikkel Christensen 
>
> [1] 
> http://android.git.kernel.org/?p=platform/development.git;a=tree;f=samples/SimpleJNI
>  
>
> On Nov 17, 12:10 am, "jon.schell" <jon.sch...@kyocera.com> wrote: 
> > I am trying to create a simple app for testing that will toggle an LED 
> > on the phone as needed.  I have the NDK set up and my c code compiles, 
> > but I don't know how to link it to the actual hardware function that 
> > would set the LED.  I'm using the actual source code for the hardware, 
> > it's not in an exposed library.  Do I need to create a static library 
> > for it to use?  Would it maybe be easier to add an android API for 
> > this somehow rather than using the NDK? 
> > 
> > For reference, this is Android 2.1 on a Qualcomm MSM7627. 
> > 
> > Jonathan

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