Monday 10 June 2013

Uselful links

I'm loosing track of good links. So I'll keep updating this post with the ones I find along with comments.

One important thing I have realized: This isn't a project where I google around, find a blogpost. And implement all the steps in it :)

The documentation is to be found in LDD3, stack overflow questions, mailing lists and, most importantly, the kernel tree itself.




Repository of patches applied to mainline kernel to make it function on the beaglebone. My work will sum up a few patches to be added to this.
https://github.com/beagleboard/kernel/tree/3.8

Set of tutorials on linux device driver development.
http://oldpapyrus.wordpress.com/tag/write-linux-device-drivers-kernel-3-0-2-6/

IIO Subsystem documentation
http://www.ohwr.org/projects/zio/wiki/Iio Interesting wiki page giving overview.

Kernel tree maintained by TI for the AM335x processors
http://arago-project.org/git/projects/?p=linux-am33x.git;a=summary

Some drivers. (Note not the main branch..)

Touchscreen driver
http://arago-project.org/git/projects/?p=linux-am33x.git;a=history;f=drivers/input/touchscreen/ti_tsc.c;h=8b3459812fef27c3f1a7801b9bf9b3bf195e34c8;hb=v3.2-staging

ADC driver
http://arago-project.org/git/projects/?p=linux-am33x.git;a=tree;f=drivers/staging;h=7c862de9e9b05ac4577665a4ed5a554d88f27acd;hb=v3.2-staging

Touchscreen/ADC driver clash patch. Part of the project is investigating the clash between touchscreen drivers and ADC drivers. The following link is a discussion on a patch solving a similar issue for another ADC.
https://patchwork.kernel.org/patch/1851101/

I skimmed the tech ref manual of the processor. The touch screen controller is a mode of the 8 channel ADC itself. As I looked at the driver sources, I found that the touchscreen driver doesn't look like its based on the IIO subsystem. The ADC driver is. The discussion in thehttp://ez.analog.com/community/search.jspa?peopleEnabled=true&userID=&containerType=&container=&q=sysfs+iio link above indicates that this is an issue in the design of the subsystem itself. It hasn't yet been designed to acknowledge that part of the ADC channels can be under use by a touch screen controller.
I will look into it as time goes on.

Analog devices wiki page on IIO
http://wiki.analog.com/software/linux/docs/iio/iio
Their ADC drivers can be a good source of example. Although, the SPI/I2C interface creates a bother. I should look at processor ADC drivers to see if I find a great one. The TI mainline one is more refined as well..

Analog community forums are slightly hidden but a good source on IIO recent questions..
http://ez.analog.com/community/search.jspa?peopleEnabled=true&userID=&containerType=&container=&q=sysfs+iio

ADC heaven for the beaglebone! Gives a great overview of the driver..
http://processors.wiki.ti.com/index.php/AM335x_ADC_Driver%27s_Guide

This guy is great with the beaglebone :)
http://hipstercircuits.com/
http://hipstercircuits.com/reading-analog-adc-values-on-beaglebone-black/ 

Temp sensor using ADC on beaglebone
http://bwgz57.wordpress.com/2012/04/01/beaglebone-how-hot-is-it/

Interesting driver guide
http://www.cedt.iisc.ernet.in/people/haresh/emsys/device_driver_brief_tutorial.pdf
 

I'll update this list as time goes on. Pretty sure I missed out on a few links already.. But I need to focus more on the content in the links itself rather than documenting the links.. :)

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