AM335x interfacing BT 656 / ITU 656

Hi Biser.

The 16 bit AM186ES 50 MHz processor did not have any video input but it was anyway possible to read the video stream to SRAM and then let the cpu encode the data. Shouldn't this also be quite possible with AM335x?

Hi Biser.

The video interface was "just" some glue logic between an 8 bit port on cpu and the video output port of the SAA7113. The SAA7113 sent video data (as of BT 656) and the DMA in AM186ES transferred the data from the 8 bit port on the cpu to the SRAM memory. Because the DMA of AM186ES was not fast enough to read the data stream, the glue logic was designed to read every x:th byte (in such a way that the color info could get preserved). The SRAM space needed was moderate, like 100-200 kB, but then the conversion was very slow. Regarding the AM335x, my idea was that the video stream should be able to read in full speed. If the data should be able to be read to DDR3 there is no problem with space. It would be interesting no learn if a) this is possible, and b) if AM335x, perhaps with help of the NEON coproc., should be able to make something of the data in real time, for example H264, MPEG4.

Hi Biser.

Ok. The problem then in this project is that we have already made most of the pcb design with AM3352 ZCZ + TPS65910A3 (following TMDSSK3358). The origin for choosing the AM335x architecture came from advice when stating that we needed to utilise a VPN solution (server) on the platform. The AM335x was well suited to run linux and then the VPN could get implemented (as well as a bunch of other custom made software). But we did also mention the demand to be able to decode image data like JPEG/H264/MPEG. Do You think that the alternatives You mention should be better suited to implement the VPN solution, as well as reading/encoding video stream? How are they compared in price (roughly)? I don't know if any of the pcb design could be reused...

Br Peter

Hi Biser.

Is it possible to get some hint on the outcome of the additional help? The very best scenario would be to be able to use our current design, that the AM335x would able to read the data stream to DDR3, and also that it would be possible to do the encoding which has been mentioned in the thread. If all this should be able to work, we should need to assign appropriate pins for the data port. We would like to get the pcb printed as soon as possible. And, if it tends to be impossible to use AM335x for this purpose, perhaps (most likely based on the current information I have) we will anyway continue with our current design/pcb. There should be some additional work (time) to choose and add the video processor (analog in, BT 656 out).

(The DaVinci alternatives which is mentioned in the thread, will some/any of them be able to implement OpenVPN in Linux?)

Br Peter

No, but that (dedicated FAE/repr.) would of course be an advantage. I have just used the ask Texas at some occasions which has worked, but it was a bit difficult to maintain an ongoing/continous dialogue. And then I have used this forum which tends to work better in the ongoing/continous aspect. Using a forum in this way is a great advantage for other developers interested of same kind of issues. And sometimes it also retricts the kind of things You are able to talk about.

Ok Biser. Thanks for the information. Br Peter

Hello Biser.

In the mean time, waiting for help on the DMA/question on AM335x, I will try to gather some more info. regarding other alternatives.

The other mcu's You mentioned above in this thread;

DM814X

DM816X

OMAP3515/03

AM3715/03

AM3517/05

as I can understand, they have all better prerequisites to read the BT 656 stream (dedicated port).

Should any of these alternatives be able to also drive a linux system with OpenVPN?

As I think I have been able to understand that the AM335x is one of the newer ARM architectures from TI, and which TI promotes. Should there be any obvious disadvantage(s) to use any of the other proposed mcu's with this in mind?

Br Peter

Hi Biser.

Well if they run linux then they should be able to use just another package like OpenVPN I suppose.

But AM335x is a more recent product compared to AM35x/AM37x, right?

Without having read up on AM35x/AM37x, is it possible to outline what should be the drawbacks in using AM35x/AM37x instead of the AM335x path which we already have been digging into for a while? Perhaps from a hardware point of view alone, if not someone else could also address the software point of view.

not exactly what the OP was looking for, but might lead to some kind of solution:

720p camera <-> am335x

http://www.quicklogic.com/reference-designs/beaglebone-camera-cape/

Hi Biser.

Have You been able to get some more information in this matter?

I have looked a bit more into AM3505, which seemed to be closest to AM3352 for our purpose. AM3505 has also hardware crypto support so there should not be any problem in getting a platform with AM3505 to do the OpenVPN (OpenSSL) etc. And, the AM3505 has the desired video port, enabling to attach some 4 input analog video encoder supplying AM3505 with BT656 data.

But, AM3505 is an older device, for example it does only support DDR2. And by looking at TI's pages, it is easy to see how the AM335x is promoted in front of for example AM3505. Also, AM335x is a bit better positioned in price.

Which also complicates this is our almost ready pcb for AM335x.

Please advice on the best way to procide.

What could I do to get some faster response? AskTexas? FAE? (FAE Where?)

Br Peter