BeagleBone Black and resistive touchscreen.

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1

Hello all! Could you help me? And sorry for my bad English :slight_smile:
I’m trying to connect BeagleBoard Black and 7’’ resistive touch screen i.q. in the Cape Board http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Dev/Beagle/4DCAPE-43(T)_datasheet_R_1_8.pdf. I used Angstrom OS and Android JB -4.2 , and connected touchscreen to AIN0, …, AIN3. But it’s not working.

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When you say “and”, I believe you mean that you tried “each” Angstrom and Android.

Regarding Angstrom, did you try the 2013-06-20 image or the 2013-09-04 image? The latest production version (2013-09-04) is at BeagleBoard.org - latest-images.

Can you be more complete in describing how it didn’t work? Did the backlight come on? Did you get a bad image?

Please include a pastebin.com of the dmesg log.

3

Thanks for you help.
I don’t use LCD Cape. I try to connect another resistive touchscreen such as in the LCD Cape. I used latest images: Angstrom, Ubuntu, Debian Android. But I can’t see any touchscreen and ADC devices.

For example I used TI_Android_JB_4.2.2_DevKit_4.1.1. But ADC is not working. And I can’t see any iio files.

root@android:/ # ls -al /sys/bus/iio/devices/iio
/sys/bus/iio/devices/iio: No such file or directory

Here is link to dmesg log: https://drive.google.com/file/d/0B9wLjHmwhZnHMEJkOFBfczdVMlE/edit?usp=sharing

4

Hello Dennis,

I did exactly the same. I connected a touchscreen without a cape. So…

  1. Capes are recognized thanks to EEPROM data, then appropriate “device tree” file is loaded which does the job, that is set hardware pins and loads + configures the driver.
  2. You don’t have a cape and hence neither an EEPROM, you need to use so-called “device tree overlay”.
  3. By default, touch screen driver is build in into the kernel, somehow, this does not play well with “overlay-ed device tree”, the kernel needs to be recompiled with the touch screen driver compiled as a module. this is because we need to load the driver after the device tree overlay is loaded.
  4. I got 10" tsc, which has bigger capacity, and the default tsc driver charging delay was not good at all, I need to modify the driver before kernel compilation.

So, It may look scary, I know. Le me know, if you know how to do the steps. I mean: are you able to configure and build the kernel? Do you know how to load device tree overlay? Do you know how to load a driver module?

I have attached my device tree file for the touchscreen, assuming it has exactly same connections as the LCD7 cape. The file shall be but into KERNEL/firmware/capes directory before kernel compilation.

Regards,
Piotr.

BB-ADC-00A0.dts (1.21 KB)

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Thank you very much for your help Piotr! Because I didn’t know what I need to do already!
Yes, I’m able to configure and build the kernel and how to load device module. But I didn’t know, that the touch screen driver needs to be compiled as a module. I thought about EEPROM module, but I didn’t know how it works. I’m trying to compile the kernel with your device tree.

What do you think about ADC drivers in Android? I can’t see any iio devices in this OS. But in Angstrom, I can see same ADC files. May be I need to compile ADC drivers as a module too?

root@android:/ # ls -al /sys/bus/iio/devices/iio
/sys/bus/iio/devices/iio: No such file or directory