Accessing GPIO and PWM on BeagleBone AI

Yes since the number of pins is less than possible interfaces...

https://www.bing.com/videos/search?q=how+to+setup+pins+beagle+bone&docid=608009253376952439&mid=30773886A1337BD47A863077…

Or a better read https://vadl.github.io/beagleboneblack/2016/07/29/setting-up-bbb-gpio .

Enjoying the BB-AI Sean_Miller ?

https://groups.google.com/forum/#!topic/beagleboard/mFTpBYv5PNI is same problem!

I saw these two references tonight in my hunt.  My thoughts were "this surely is handled in by the bonescript and Python libraries on the fly, right?"  "Otherwise, it would be in the comments in the header, right?"  I guess not.

For the video, I didn't have the directories he showed for the capes and trees.

I tried the redirect to export tricks, but still received the same error of having no pinmux.

I'll run it harder through the paces tomorrow evening.  I found the tutorials just aren't out there like you find for Raspberry Pi and Arduino IDE driven microcontrollers.

But, so, far, I love the idea of computations happening at the speed of the frame with the tidl libraries, love the Cloud 9 interface (1st time using it), and love being able to use it as an adhoc device while its connected to the internet.

Just got to get an LED to blink and stop it from calling my black cat a ping-pong-ball. 

-Sean

Just got to get an LED to blink and stop it from calling my black cat a ping-pong-ball. 

LMAO

#include <unistd.h>

#include <stdio.h>

using namespace std;

int main()

{

   FILE *export_file = NULL; //declare pointers

   FILE *IO_direction = NULL;

   FILE *IO_value = NULL;

   char str1[] = "0";

   char str2[] = "1";

   char str3[] = "out";

   char str[] = "23";

   //this part here exports gpio23

   export_file = fopen ("/sys/class/gpio/export", "w");

   fwrite (str, 1, sizeof(str), export_file);

   fclose (export_file);

   //this part here sets the direction of the pin

   IO_direction = fopen("/sys/class/gpio/gpio23/direction", "w");

   fwrite(str3, 1, sizeof(str3), IO_direction); //set the pin to HIGH

   fclose(IO_direction);

   usleep (1000000);

   for (int i=0; i<10; i++){ //blink LED 10 times

        IO_value = fopen ("/sys/class/gpio/gpio23/value", "w");

        fwrite (str2, 1, sizeof(str2), IO_value); //set the pin to HIGH

        fclose (IO_value);

        usleep (1000000); //delay for a second

        IO_value = fopen ("/sys/class/gpio/gpio23/value", "w");

        fwrite (str1, 1, sizeof(str1), IO_value); //set the pin to LOW

        fclose (IO_value);

        usleep (1000000); //delay for a second

        }

}

The 3 bold lines are the setup for pin 23.

The only thing I could find out about this issue is that the device tree files for the BB-AI are missing, there is currently no suitable file provided for the BB-AI
all the BBB black files just brick the BB-Ai if loaded with uENv.txt. the Universal cape also does not support the processor.
I raised an Issue on the github for the examples and messaged them,. hope Beaglebone will shortly provide a suitable overlay file /inlcuded it loaded in the next OS image release.

thanks for posting your solution!

For generall usage these setup procedures should be handeled in a Library or the u-boot (like intended).
To get an urgent project working i had to do some workaround which thought me about interfacing it with USB devices, but I really would like to redo it without any additional hardware.

Sean, I am definitely not a nodejs expert, but I compared your code to the example from cloud9 on my BBBlack (I don't yet have a BB AI).  In the given example, the first 3 lines read:

   var b = require('bonescript');

   var inputPin = "P9_38";

   var outputPin = "P9_14";

Your code reads:

1. const b = require('bonescript');
4. const inputPin  = "A3";
5. const outputPin = "P9_14";

Is there a reason you used constant instead of variable?

My code came from the example code found in the Cloud9 IDE under cloud9-->BeagleBone--AI which is on the BeagleBone GitHub as well.

https://github.com/beagleboard/cloud9-examples/tree/master/BeagleBone/AI

As for const versus var, in general, I do prefer const for a variable I don't want to mistakenly change its value, as in this case.  I want to set it and fix it to that pin for all references.

See ya',

Sean

Thanks for posting.

Another file/shell based BoneScript workaround was in that post you sent as well:

/*------------------------------------------------------------------------------------
function to export a gpio Pin
    Parameter : the pin that you want to export  
*/
function gpio_export(pin)
{
    
    var path_export=path+"/export"; // export path

    //method where we execute the shell command

     var command = "echo "+pin.toString()+" > "+path_export //the shell command that want to do
    
     //execution of the command
       process.exec(command,function (err,stdout,stderr) {
            //if there is some error print them
            if (err) {
                console.log("\n"+stderr);
            } else {
                console.log(stdout);
            }
        });

}

But, this makes for a negative demo if I blog and make a video on it.  Someone on the fence on going to BeagleBone could get turned off immediately.  Ping-pong-ball and I are gonna keep digging in hopes find the magic.

-Sean

I got excited when I read this article on Adafruit:  https://learn.adafruit.com/introduction-to-the-beaglebone-black-device-tree/overview

But then I read your post that the BeagleBone Black overlays will brick the AI.

Oh well, at least I understand it now, just not enough to make my own overlay.

See ya',

Sean