Accessing HDMI (and other interfaces)

[EclecticMonk]

Hi there,

although I've been playing with a board for a couple of months and silently reading and collecting feedback from the forum, this is my first post and so I'd like to take the chance to say hi everyone.

After getting familiar with the internals of the Epiphany chip and the SDK, I decided to start playing with the interfaces to make lights blink and show shining colors in the screen. I've been trying to reuse code from the Mandelbrot example to understand how to output images to the screen, but I've been unable to get all the details. As a start, I just tried to replace the Mandelbrot output by a constant number, so I could get a fixed color in the screen; but even that simple step has turned to be more complicated than expected. Depending on where I modify the value, I get nothing on the screen, runtime errors, or hang the complete system and needed a couple of reboots to get it back.

I've to say that I'm using a brute force approach just trying different combinations and seeing what happens, but this is because I haven't found any details on how to correctly access the interfaces. Is there any documentation specifying ho to access the interfaces? What are their memory addresses, required format of the output data, synchronization issues, etc. ? Are there related drivers? I've skimmed through the documents and the forum and haven't found anything related, other that trying to reverse-engineer the examples. Am I overlooking or missing some document/guide?

My next step is to try some video processing tasks, and then continue checking the other interfaces for more IO functionality. We plan to use it for teaching purposes later, so it's important to have these steps clear. Any pointer would be greatly appreciated.

Cheers

[notzed]

[EclecticMonk]

Hi notzed,

that's the most outstanding answer I've ever received in a forum. I'm glad that you didn't had anything better to do by the time you wrote it .

It's crystal clear now. I was basically overlooking a huge detail: I've been working and debugging FPGA prototypes and bare metal embedded processors for so long, that I've developed a tendency to try to understand every single detail on the interfaces, and then I was just overlooking the benefits of having a complete OS running on the ARM. I was looking for info at the hardware level, but didn't think about looking at the kernel level. So thanks for the wake up call, I guess everything is going to be a little easier now.

I'm going to check your example and the provided links. I own you a beer

[claudio4parallella]

That's exactly what I need for my CLUSTER of 64 cores (4 parallellas).

The fact is that the IMG ubuntu-14.04-headless-z7010-20150130.1.img to be used for the eLink Cluster have not any Frambuffer or HDMI support.

Any solution please? thanks