GPIO on AM3517EVM

Christian Richter

Hi all,

I need to evaluate usage of GPIO on Android at AM3517EVM.

For this purpose I want to toggle one of the USER-LEDs of the board by console-commands.

I found out I had to export an interface to toggle a GPIO-Pin, after that set the direction of the Pin and finally set the value...

that should be no problem by piping the right echo-commands to /sys/class/gpio/...

But I don't know which GPIO-Pin I have to toggle, or if I have to make further changes on the system...

Can anyone help me there?

Kindly regards,

Christian

over 13 years ago

0 Anil over 13 years ago

TI__Expert 6655 points

Hi Christian,

Identify the GPIO pin number from schematics depending upon which USER-LED you want to control. Then follow the instructions at

http://processors.wiki.ti.com/index.php/GPIO_Driver_Guide

Run these commands to know which GPIO's are in use

$ mount -t debugfs debugfs /sys/kernel/debug

$ cat /sys/kernel/debug/gpio

Regards

AnilKumar

Please mark this Forum post as answered via the Verify Answer button below if it helps answer your question. Thanks!

0 Christian Richter over 13 years ago in reply to Anil

Intellectual 340 points

Hi Anil,

thx for fast reply, this as a little useful, but I still don't know which Pin I really have to toggle by sysfs commands...

the Problem is I know from Schematics, they are on GPIO-expander "P06" (name in the block) and "P07" (name in the block) and go out on the real expanderpins 10 and 11 (stands above the line, which sands for the outgoing Signals), but I still don't know the Offset for the expander, cause there are several GPIOchips configured in the GPIOinterface...

hope i formulated the problem understandable and you or someone else can help me further...

Regards

Christian

0 Anil over 13 years ago in reply to Christian Richter

TI__Expert 6655 points

Hi Christian,

Go through this post and implement the same for you case.

http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/717/t/169644.aspx#619865

In the schematics first page we can see that I2C address is 0x20

Regards

AnilKumar

Please mark this Forum post as answered via the Verify Answer button below if it helps answer your question. Thanks!

0 Christian Richter over 13 years ago in reply to Anil

Intellectual 340 points

Hi Anil,

thx for your reply, setting userLED from sysfs is no problem now...

By the way I found out which gpiochip I have to use by looking on /sys/bus/i2c/2-0021/gpio (cause at schematics I see 0x21 as i2c-address for the right GPIO-Expander)

After having the Offset from the "gpiochip192" it was no problem to export the right gpiopins.

Next step will be to read/write GPIOs from Android-application, therefor I want to use Native-Code over the Android-NDK, are there further changes to do on the image for that??

BR,

Christian

0 Anil over 13 years ago in reply to Christian Richter

TI__Expert 6655 points

Hi Christian,

That is sufficient, You can control the LED from the sysfs entries, details can be found in GPIO user guide.

Regards

AnilKumar

0 Christian Richter over 13 years ago in reply to Anil

Intellectual 340 points

Thx Anil,

can you post a link to this UserGuide?

BR,

Christian

0 Anil over 13 years ago in reply to Christian Richter

TI__Expert 6655 points

Hi Christian,

I am talking about the Linux console (Not from Andriod console), link is already provided above

http://processors.wiki.ti.com/index.php/GPIO_Driver_Guide#Sysfs_control

Regards

AnilKumar

0 Christian Richter over 13 years ago in reply to Anil

Intellectual 340 points

Hi Anil,

by the it was no problem over adb shell. ;-)

But now, I don't wanna do it over console anymore, my next step should doing it from an Android-Application...

So what I wanna do is searching a C-Code library, writing a little test-programm for read and write special gpio-pins and port this to Android with the NDK...

Should this work or may I running into issues?

BR,

Christian

Processors

Processors forum

GPIO on AM3517EVM