is anyone successfully using i2c OLED / LCD?

I guess you could look at the docs for the ones you have and see if you can modify the library for those!

giuliomoro I guess you could look at the docs for the ones you have and see if you can modify the library for those!

yeah will do. i will still hook up my displays to the existing library and see if i get some gibberish output (and check if the i2c port is correct etc.) from what i remember those 2 display types are very similar and i got gibberish output when i tried them on axoloti with the wrong driver.

ok, well first tests failed :-(
will wait for the compatible display and take it from there.

can you post the actual code you have in your Bela project?

here you go, for now it's only the basic but altered render.cpp:

#include <Bela.h>
extern "C" {
int oled_main(void);  // declare the oled_main() function from Main.c
}
AuxiliaryTask oledTask;
void oledTaskFunction(void*)
{
    while(!gShouldStop){ // run the content of the loop until the program stops
        oled_main();
        usleep(50000); // always sleep in a busy loop to avoid hogging all the CPU
   }
}
bool setup(BelaContext* context, void* userData)
{
    Bela_createAuxiliaryTask(oledTaskFunction, 1, "oledTask", NULL);
    Bela_scheduleAuxiliaryTask(oledTask);
}
// optional: add some sound generator into render()

void render(BelaContext *context, void *userData)
{
}

void cleanup(BelaContext *context, void *userData)
{
}

I see... to be honest I'm not yet very knowledgeable about such inner workings, for now I'm just trying to get your code working as you suggested it earlier in this thread.

Adding oledTask = and cleaning/recompiling the project still gives me a Segmentation Fault:

Running project...
(Main)i2c-1: Bus Connected to SSD1306
Segmentation fault
Makefile:524: recipe for target 'runide' failed
make: *** [runide] Error 139

This is better. You see that now it is actually running the task (as you can tell from the fact that the line

(Main)i2c-1: Bus Connected to SSD1306

is printed).

I started debugging this by copying all your code to the board and trying to run the files from your repo as a stand-alone app, and that would fail at compile time. I fixed it with this.

Then, I managed to build a stand-alone program (non-Bela) and run it, but it would only display (Main)i2c-1: Bus Connected to SSD1306 and would not actually show anything on the display.
Did you see the test animation on the display?

Next thing I did was to check out the upstream code (basically, your code without your changes), which is hardcoded to use I2C-2. Once I managed to get it to build (needed the same fix as above), it ran just fine.
I also fixed a buffer overflow that was an accident waiting to happen.

I applied some minimal changes to be able to use i2c-1, without having to go through the whole renaming process you undertook.

After that, the stand-alone application works fine on i2c-1 as well.

Then I copied the files thus updated into the project, and I got to the same point you were at:

crosswick Running project...
(Main)i2c-1: Bus Connected to SSD1306
Segmentation fault
Makefile:524: recipe for target 'runide' failed
make: *** [runide] Error 139

(note this took me over 1 hour, and I could have saved all of that time if you had sent me the code ready to test).

The compiler actually gives you a warning that is the key to solve the issue:

/root/Bela/projects/ssd/render.cpp:17:1: warning: control reaches end of non-void function [-Wreturn-type]
}
^
1 warning generated.

This means that you are supposed to return a value from setup() and you are not. If the initialization goes well, you should return true.

So this works for me:

bool setup(BelaContext* context, void* userData)
{
    oledTask = Bela_createAuxiliaryTask(oledTaskFunction, 1, "oledTask", NULL);
    Bela_scheduleAuxiliaryTask(oledTask);
    return true;
}

For the avoidance of doubt, here is a repo containing a complete Bela project where this code is working correctly. Note that the program may take a while to stop after you hit stop, because the oled_main() function takes forever to return.

Thanks @giuliomoro. First off, to address this:

giuliomoro (note this took me over 1 hour, and I could have saved all of that time if you had sent me the code ready to test).

I highly value your time and enormous help on this forum... I had doublechecked that the code worked on my Bela Mini before I uploaded it to github. I just checked again and these steps work for me:

• download the .zip from https://github.com/crosswick/SSD1306-OLED-display-driver-for-BeagleBone
• in the Bela interface, create a new C++ project called 'OLED_test_github'
• use 'Upload file' to add the seven relevant .h and .c files to the project
• with Terminal and ssh root@192.168.7.2, navigate to Bela/projects/OLED_test_github
• run gcc *.c -o oled which returns a bunch of warnings but no errors;
• run ./oled which makes the display connected to ic2-1 perform the test animations.

My Bela Mini is running v0.3.6b, which I believe is the latest version.

giuliomoro This means that you are supposed to return a value from setup() and you are not. If the initialization goes well, you should return true.

Great! it also works for me. I can now go on to test out these display functions from within PD; my plan is to use the customRender PD example project as a starting point.

Thank you!

giuliomoro Can you run grep v0 /etc/motd on the board? What does it return?

Bela image, v0.3.6b, 23 October 2018

and grep linux /root/Bela/projects/OLED_test_github/* ?

giuliomoro and grep linux /root/Bela/projects/OLED_test_github/* ?

/root/Bela/projects/OLED_test_github/I2C.c:#include<linux/i2c.h>
/root/Bela/projects/OLED_test_github/I2C.c:#include<linux/i2c-dev.h>
grep: /root/Bela/projects/OLED_test_github/build: Is a directory
Binary file /root/Bela/projects/OLED_test_github/oled matches

and what's the output of

dpkg -l | grep i2c

?

ii i2c-tools 3.1.2-3 armhf heterogeneous set of I2C tools for Linux

I did use i2cdetect earlier to check whether the display module was connected... I don't recall exactly if I installed it or if it was already there. Maybe that makes a difference?

let me know if I can be of any further assistance. I think it might be best for me to first work on the PD integration and after that write up a how-to.