Rotary encoder project

j-maathuis · 2015-12-01T08:02:21.000Z

As far as I’ve read you need to include some things from source in the devicetree and that’s only possible while compiling a new firmware: something I’ve absolutely never done before and don’t want to try that myself as a noob in such things.

I think the piece of software sourcecode is a sourcecode of Linux before compiling the firmware.

frietpan · 2015-12-01T12:33:04.000Z

it’s slowly falling into place

The behaviour of this driver can be altered by setting some parameters
from the insmod command line.
The following parameters are adjustable:
bus0 These four arguments can be arrays of
bus1 1-8 unsigned integers as follows:
bus2
bus3 <id>,<steps>,<axis>,<gpioa>,<gpiob>,<inverted>
If this driver is built into the kernel, you can use the following kernel
command line parameters, with the same values as the corresponding module parameters listed above:
rotary-gpio-custom.bus0
rotary-gpio-custom.bus1
rotary-gpio-custom.bus2
rotary-gpio-custom.bus3

So now my question is:
Is it build into the kernel or not? How can I check this? If it is NOT build into the kernel then i should be able to use the insmod command to configure it.

I need to read this a few more times… And do more searching on the topic…

a bus seems to be 1 encoder, so if we had more GPIO’s then we could add 3 more encoders…
We have only one so to configure it on bus0 there should be something done like:

insmos bus0 <id>,<steps>,<axis>,<gpioa>,<gpiob>,<inverted>

id = ?
steps = ?
axis = ?
gpioa = gpio16 (the CLK signal)
gpiob = gpio17 (the DT signal)
inverted = 0 (or 1 to swap gpio a and b)

not sure what else we need to know

frietpan · 2015-12-01T13:47:08.000Z

Do I get this right?
kmod-input-gpio-encoder and kmod-rotary-gpio-custom are kernel modules so once they are installed then they are added to the kernel. So then all would be working. And we do not need to use the insmod command line.
but but but… we still need to tell it on what GPIO we have something connected right?

alzhao · 2015-12-01T15:29:10.000Z

I don’t think GPIO24 and SPI_SW are available in AR150.

frietpan · 2015-12-05T08:02:33.000Z

After a few days of digging i finally found where the rotary encoder stuff was installed.

/sys/module/rotary_encoder

I still don’t know how I tie it to GPIO 16 and 17 any hints are welcome.

j-maathuis · 2015-12-05T08:04:13.000Z

/me is still awake and a bit bored.

Connecting and starting up the GL-AR150.

Digging a bit into it.

frietpan · 2015-12-05T08:17:27.000Z

Archaeology of the 22nd century… someone dug up a severely hacked AR150 and screamed AAAAAAAAAAAAAAAAAAAAAAaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa WTF???

j-maathuis · 2015-12-05T08:19:05.000Z

/sys/module/rotary_encoder is a directory
I went to /sys/module/rotary_encoder/drivers/platform:rotary-encoder which is a symlink to /sys/bus/platform/drivers/rotary-encoder
This directory contains the directory’s “bind”, “module”, “uevent” and “unbind”.
After some searching on Google I found out we probably have to bind a driver: Manual driver binding and unbinding [LWN.net]
I’ll keep on investigating now, sooner or later.

j-maathuis · 2015-12-05T08:34:35.000Z

Às mentioned above in post http://www.gl-inet.com/forums/topic/rotary-encoder-project/#post-7363 you have to assign something to a key called “rotary-gpio-custom.bus0” (and also bus 1 till 3).

Here is a topic that describes not exactly the same, but about pressing GPIO keys: http://www.avrfreaks.net/forum/gpio-key-device-doesnt-get-installed

I did see something in the topicstart:

I wonder if there should be a directory like it is in /sys/bus/platform/drivers/leds-gpio bind leds-gpio.2 uevent unbind

Maybe this will gice us some clue?

frietpan · 2015-12-05T10:37:11.000Z

just got home,
I think you could be right,

Something in the area of gpio_a.16 and another with gpio_b.17 This needs a few days to find a braincell that’s a bit more digitally minded then the others

rotary-gpio-custom.bus0.gpio_a.16
rotary-gpio-custom.bus0.gpio_a.17

And also for id, steps, axis?

Or am I again thinking in the wrong direction here? (or too far ahead)

frietpan · 2015-12-05T17:11:13.000Z

I think bus1, bus2 and bus3 can be left empty. The driver can handle 4 rotaties I have read somehere

But it’s not clear what values are expected for id, and axis.

Steps is most likely “20” that’s the number of steps of the rotary to make 1 full circle.

I wonder if we can find in the sourcecode what kind of value’s it expects?

frietpan · 2015-12-08T05:19:16.000Z

after a lot of digging i cae across this page: http://lxr.free-electrons.com/source/Documentation/input/rotary-encoder.txt

It looks like this should now be all the info i need… and now i need to look how to enter the correct commands to set these values. That’s for tomorrow…

I need <id>,<steps>,<axis>,<gpioa>,<gpiob>,<inverted>

These are the values that I have in mind:

id = 0
steps = 20,
axis = ABS_X,
gpio_a = 16,
gpio_b = 17,
inverted = 0,

rene · 2015-12-08T08:37:37.000Z

Hey Frietpan first greetings to the netherlands from germany near the border !

You could take a look here: Build Your Own Wifi Radio : 14 Steps (with Pictures) - Instructables this guy is using a openwrt router to make a webradio,using a rotary encoder with a microcontroller. i think it could be done by adding a arduino nano or something else into the router this should be a solution for your problem

also take a look at this: Building a Wifi Radio – Part 8, Adding a Tuning Control | MightyOhm

frietpan · 2015-12-09T04:52:53.000Z

Greetings Rene! Are you in the Aachen area perhaps? (near the Dutch mountains)

Thats a nice project! However, it uses an ‘expensive’ atmel to do the GPIO stuff. It looks less complicated then the route I took. Once this encoder stuff is figured out it should make things more easy. By connecting the encoder directly to the SoC there is no more need to use an extra chip do add a basic selector switch / control knob.

I want to use it as a volume knob / light dimmer and also as a OpenWrt config selector. … yeah too many ideas…

The most practical use would be a config selector for a travel router. By making additional config folders ie /config1, /config, /config3, etc. When you turn the knob then another folder is used. This way you could store an endless number of configurations… Just by connecting a rotary to the GPIO’s But I’m not there yet… Getting close though. I’m now at the point where i have to figure out what kmod-rotary-gpio-custom wants to know exactly.

I have tried a few things but since i’m not comfortable with it yet i hope i don’t mess up anything.

rene · 2015-12-09T05:37:38.000Z

Yes i understand, but i´m not sure if the soc can handle the timings of the LOW/High´s from the encoder… sadly my rotary encoder is on its way from china to germany, will test in about three weeks xD

i´m located Near Borken (near in the Netherlands Winterswijk)

frietpan · 2015-12-09T08:18:11.000Z

Cool,

I also had my doubts, but afterall there is kmod-input-gpio-encoder and kmod-rotary-gpio-custom these drivers seem specifically made for using encoders on GPIO pins. A little bit hard to understand how they work, but it’s all there and they seem to exist for quiet some time for linux. And the AR9331 SoC seems to be modern enough. It would be great if someone with more knowledge would jump in and tell us the secrets but it looks like we are the pioneering pirates. HAR HAR!

Now i also have to build a Radio. Then I can tune in to one of the streams from Culturserver.de

Borken That’s not too far from here. It’s a little up north from Airport Weeze right?

I’m 15 minutes south of Eindhoven.

rene · 2015-12-09T09:35:52.000Z

i´m good thank you, i´ve just ordered a rotary from the uk! http://www.ebay.de/itm/311219577453 looks really nice

Should be arriving in a few days i hope! Yes the Radio Project does looks good sadly i´m not good at building cases!

i´m located in the Ruhrgebiet,Eindhoven is 1 1/2 hour far away from here by car (144km)

frietpan · 2015-12-10T04:50:40.000Z

It even has all the resistors mounted! In my case the pull-up of de SW was not mounted.

Plastic breadboxes and tupperware boxes make low cost enclosures for prototypes.

Ruhrgebiet now I have to download a few Schimanski episodes to get in the mood and make plans for a visit.

rene · 2015-12-10T08:38:12.000Z

Schimanski i´m waaaaaayyy too young for this! (25 years old)

but if u come to the ruhrgebiet we should drink a beer!

hope the rotary encoder arrives soon so i can compile my own openwrt and do a little bit soldering!^^

Will share my results for sure

j-maathuis · 2015-12-10T08:40:24.000Z

That would be great!