DLP670S: video-pattern mode is not working

Hi che evg,

Are you using our DLPLCRC900DEVM and DLPLCRC67EVM for this, or is this a custom design?

May I get a video of what this looks like along with pictures of your board(s)? Is this strange pattern reproducible, or does it seem to be intermittent?

When you say only half the DMD changes state sometimes, are you referring to just one side, or does this happen to both sides, where one time it happens, it is just left side, and other times it might be right side?

On top of tightening the DLP screw (top picture below) for the DMD, are you also ensuring the screws for the flex cables are tightened correctly and not bent in too small of a radius?

che evg said:

I lost vide-pattern-mode. It simply stops to work next day.

Some times I have nothing on the DMD, sometimes first image of sequence, sometimes only half of dmd change the state.

What do you mean by it stops working the next day? Is it recoverable? When video pattern stops working, are you able to successfully change modes? If yes, are you able to switch back to video pattern mode and have it work correctly?

Regards,
Michael Ly

che evg,

I took an even closer look at your status flag bar and see that you have a sequence abort error.

The first though that comes to my head, while running in video pattern mode, is that you have attempted to put too much data into a single frame.

Are you using HDMI or DisplayPort? If using HDMI, you are limited to 30 Hz max rate. That means each of your frames is approximately 33.33 ms.

There will, of course, be some give and take to what is exactly 33.33 ms, however. Perhaps there is an event where it misses this timing and causes the sequence abort?

Let me check with a colleague to see if being off by this much is reasonable for our system, as video pattern mode is designed to be pixel-accurate.

Please give me until Thursday of next week, as said colleague will be out of office until Tuesday.

Regards,
Michael Ly

Dear Michael Ly,

thank you for attention,

1 - DLP is bought directly from TI,

2 - The "strange pattern" I saw with other one PC, not with mine, I will try to reproduce and make a video (or a photo).

3 - when it was a half of image it was the same half

4 - bent radius is not too small, I will tight flex screws, for now it is not accessible

5 - I finished some set of test successfully, and next time it was not working, it means it happens not during my tests but between them

6 - I can change modes, and all of them are working, image is perfect, but nothing for video-pattern mode

7 - I'm using HDMI and only one wavelength light source

I need to do some changes in optical scheme and repeat my test, I will inform you if there are some changes.

thank you.

Hi che evg,

Thank you for the update!

Regards,
Michael Ly

Hi che evg,

I talked with my coworker, and he said that, due to jitter, we can probably expect around a 5 us or so shift in timing due to jitter. This looks like 18 us total, which should normally be okay.

My colleague also mentioned that you should be using GUI 5.2 with firmware 6.2.0. We gleaned this information from the screenshot you took of your GUI.
5.0.0 may  have an issue that we call "black banding" where a horizontal line or lines appear on t he screen, and you must  perform a reset on your board.

May I ask what direction the stripe you see is going toward? Is it up and down or left to right on the half of the DMD you are seeing?

One other point mentioned is to untighten the DMD, take it out, and place it  back into reposition it. Then tighten once more.

The DMD flex cables may need to be removed. Clean the PCB connections with isopropyl alcohol (IPA), and attach and screw the flex connectors back on. Sometimes these get dirty and do not make proper contact.

Thank you,
Michael Ly

P.S. Are there any updates on test, or have you figured it out at this point?