How to use current universal cape device tree and ADC at the same time

[niv...@gmail.com]

Hi,

In continue to my IRC chat with rcn-ee, I need more help to figure this out.

I am using a beaglebone green and the lxqt image and kernel 4.1.13-ti-r35 .

I want to use the on-board button connected to P8_43, so I need to setup pull up for this gpio.

I also want to use the analog to digital converter (ADC) to sample an input.

The universal cape used to load on boot, and I used to use config-pin P8_43 in+ to setup.

rcn-ee askd me to git pull in /opt/scripts, which I did, and I also ran apt-get upgrade on the full OS.

Now after boot when I try to run  config-pin P8_43 in+ I get this error:

cape-universala overlay not found

run "config-pin overlay cape-universala" to load the cape

Yet /lib/firmware/ has no file named cape-universala-00A0.dtbo.

1. So my first question is how to allow the use of config-pin after this upgrade.

2. How to load the ADC device tree and module? seems config-pin overlay BB-ADC is ok, but should I load it after the universal cpae?

Thanks,

Niv

[Soapy Smith]

Hi Niv-

I've been looking at the kernel 4 implementation of device trees today.

Here are a couple of things which may help.

cd to this directory:

/sys/devices/platform/ocp/ocp:cape-universal

ls and you should see a file called status.

cat status

This should give you a listing of the currently enabled GPIOs.

"ocp" means "on chip peripheral".  A GPIO is one of several types of ocp.

Here is the first few lines of what I see on my BBB:

 0 P9_92                    114 IN  0

 1 P9_42                      7 IN  0

 2 P9_91                    116 IN  0

 3 P9_30                    112 IN  0

 4 P9_27                    115 IN  0

 5 P9_26                     14 IN  0

 6 P9_24                     15 IN  0

 7 P9_23                     49 IN  0

 8 P9_22                      2 IN  0

 9 P9_21                      3 IN  0

This continues on and shows GPIOs enabled on the P8 header as well.

So just taking an example P9_27:

config-pin -q P9_27

P9_27 Mode: default Direction: in Value: 0

The command runs successfully.

Now, try the command on a pin which is not listed in the status file:

config-pin -q P9_28

P9_28 pinmux file not found!

cape-universala overlay not found

run "config-pin overlay cape-universala" to load the cape

So I reproduce the a similar result as what you see for P8_43.

There is no overlay cape-universala being compiled by Robert's script.

The command config-pin was written by another person and is described here:

https://github.com/cdsteinkuehler/beaglebone-universal-io

I suspect the error message being emitted by config-pin needs to be updated.

Otherwise, the first part of the error message is correct in that the GPIO is not active on the pin.

The pin you need as a GPIO P8_43 needs to be designated as such by the overlay file.

Now, the question is, does one of the existing overlay files have this pin designated as GPIO?

Regards,

Greg

[niv...@gmail.com]

Solved last night by Robert rcn-ee:

First upgrade your overlay, to include the fix for P8_43:

$ cd /opt/source/bb.org-overlays/ ; git pull 

Then build the device tree overlays:

$ ./install.sh

This created the missing cape-universala-00A0.dtbo and copied it to /lib/firmware

Now I had a choice, should I have the cape-universal load on boot, for this do:

 in /boot/uEnv.txt find, cmdline=.... and add "cape_universal=enable"

Yet I chose not to do this but use my own systemd service to setup the GPIO, I posted the how to here.

I then have another service to load the ADC device tree.

and it all works fine

[Soapy Smith]

I don't see any difference.  When I use the command git pull, the command line response is "Already up-to-date.".

 

I had already removed the bb.org-overlays directory and git cloned from

 git clone https://github.com/beagleboard/bb.org-overlays

After ./install.sh, I see the same dtbo files in /lib/firmware.

Are you sure "git pull" is all that is required?

Another question I have on this overlay system:  What determines the overlay which is loaded at boot?

Is there another influence besides the uEnv.txt file?

A cape board can have an EEPROM which describes the overlay to apply.

I know there is also an EEPROM on the BBB as well.  Does this one also contain a default overlay which

is loaded in the case of no cape?

Regards,

Greg

 

[lucas]

I also did the git pull in the overlays directory and the ./intsall.sh, but the cape-universala overlay did not appear in the /lib/firmware directory.  I searched the whole repository and as far as I can see an overlay with the name cape-universala has never existed. Any ideas how to resolve this?