DLPC900: Video pattern mode, blank images in bitplanes G0, R1

Hello Giorgio,

Can you tell me a little bit more about the incoming source.  Specifically, what frame rate are you bringing in the RGB stream.  This is to see if we can recreate the same here.

Fizix

Hi Fizix,

thanks for your relpy. Our RGB stream has a frame rate of 60Hz (single pixel mode, DisplayPort) and we use either an Nvidia GTX 1050 Ti or an integrated intel HD graphics 4600.

During the stream, the DMD is always locked with the source. The swap is set to: ABC -> BAC.

For example, if we send the following RGB image (made of letters 'R0' in case of bitplane R0, 'B0' in case of B0, etc.):

We observe the corresponding 'letters' for all bitplanes except G0 and R1. We fear that we have damaged some electrical components (capacitors?) relative to G0 and R1, but we do not know which elements to test as the manual of DLPC900 is not very exhaustive.

Cheers,

Giorgio

Hi Giorgio,

Thanks for sharing information.

We will test from our side and get back.

Thanks,
Shivakumar 

Hello Giorgio,

While my colleague is attempting to recreate this in our lab, can you do the following test.

With the set up the same, can you create a quick project that displays G0 as a 1-bit patter for the entire frame time.  Use 15000 us as it will be plenty to observe the pattern.  And similarly for R1. 

Let us know if you can observe the G0 and the R1.  This will help determine if the receiver subsystem is having an issue.

Fizix

Hello again Giorgio,

After careful reading, it looks like you have covered most of the debug bases, so I crossed out the request in the previous message.  The only other test we would ask is to try changing the swap to another order, perhaps ABC -> ABC.  Does the issue occur, does it move to the coresponding position matching the physical line?

We don't expect it to change anything, but could you also try HDMI for comparison?

Fizix

Hi Fizix,

thanks for the follow up and sorry for the late answer.

We still have not found a solution for this issue.

We tried to swap the input channels via the GUI, but we still cannot generate any image in the bitplanes G0, R1, while the other bitplanes are working as expected.

Giorgio

Hello again Giorgio,

Just to confirm, swapping channels did not move the missing patterns to another color.  The missing G0, R1 were still missing.  If it were on the inbound from the ITE receiver, I would have expected the missing data to have moved to different colors  So if you sent G-->R, R-->B, and B-->G I would have expected R0 and B1 to be missing.  But it did not switch them, is this correct?

This tells us a little bit more of where the issue may be.

Fizix

Hi Fizix,

yes what you are saying is correct.

Giorgio

Hello Giorgio,

The fact that the missing bits did not move to R0 and B1 with the swap suggest that the issue is happening after the controller has assigned the bits to the particular colors.  

Let me consult with our ASIC expert(s) on this chipset.  Please allow a couple of day.

Fizix

Giorgio,

This is taking a little longer than expected.  I will prod the ASIC guys again.

Fizix

Giorgio,

The ASIC team is also baffled by this.  If you slow down the frame rate to 30, does it change or remain the same?

It will be possible in the near future to purchase just the controller board alone.

When did you purchase this kit?

Fizix

Giorgio,

Do you still need assistance with this thread?

Fizix

Hi Fizix,

thanks for your last messages. At the moment we cannot do the test in video pattern mode at 30 fps, but probably this is no longer an issue as we adapted our experiment to drive the DMD in 'pattern-on-the-fly' mode.

Good to know that in case we can purchase only the controller board. We purchased the kit on the 11th December, 2019.

Kind regards,

Giorgio