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DLP6500FLQ: Missing the patterns while capturing with camera

Chaitanya Mididoddi
Prodigy 140 points
Part Number: DLP6500FLQ
Other Parts Discussed in Thread: DLPC900

Hi,

I am using video pattern mode to display RGB images in series on DMD DLP6500 and 24 bitplanes(R0..R7,G0..G7,B0..B7) for each RGB image are projected on DMD and captured with camera.

Camera acquisition is based on trigger output2 on falling edge. The frame exposure time is 20ms. I would expect 2880 images. However I miss 16 or 17 bit plane patterns out of 2880. I thought the trigger out pulse width is too narrow to capture and delayed the falling edge to 10ms(Half the frame rate) but the issue hasn't been solved.

Could you please let me know how to obtain all the patterns reliably without missing any.

A) Would it be the issue with trigger output I am using. Should I be using the trigger output 1 with some dark time?

B) Or is it something to do with refreshing rate of DMD?

I have attached the batch file I created to display 2880 patterns.

Regards

Chai

Fullscreen batchfile_veideopatternmode2.txt Download 
DISP_MODE : 0x02
PAT_START_STOP : 0x00
MBOX_DATA : 0x00 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x00
MBOX_DATA : 0x01 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x08 
MBOX_DATA : 0x02 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x10 
MBOX_DATA : 0x03 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x18 
MBOX_DATA : 0x04 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x20 
MBOX_DATA : 0x05 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x28 
MBOX_DATA : 0x06 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x30 
MBOX_DATA : 0x07 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x38 
MBOX_DATA : 0x08 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x40 
MBOX_DATA : 0x09 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x48 
MBOX_DATA : 0x0A 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x50 
MBOX_DATA : 0x0B 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x58 
MBOX_DATA : 0x0C 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x60 
MBOX_DATA : 0x0D 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x68 
MBOX_DATA : 0x0E 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x70 
MBOX_DATA : 0x0F 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x78 
MBOX_DATA : 0x10 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x80 
MBOX_DATA : 0x11 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x88 
MBOX_DATA : 0x12 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x90 
MBOX_DATA : 0x13 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0x98 
MBOX_DATA : 0x14 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0xA0 
MBOX_DATA : 0x15 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0xA8 
MBOX_DATA : 0x16 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0xB0 
MBOX_DATA : 0x17 0x00 0x20 0x4E 0x00 0x11 0x00 0x00 0x00 0x00 0x00 0xB8 
PAT_CONFIG : 0x18 0x00 0x40 0x0B 0x00 0x00 
PAT_START_STOP : 0x02

  • 0
    TI__Guru 54705 points
    Chaitanya,

    I am not sure why you are triggering on the falling edge (or are you inverting the the trigger) rather than the rising edge?

    Typically what you are seeing is a result of the memory buffer size of the camera and interface speed to your PC. Are you sure your camera can capture, buffer and download fast enough to keep up with 2880 frames in the total capture time.

    Please go to the Video Pattern Mode tab and the Menu item "Save" and save the file from your video sequence and post that.

    I also notice that you only have 18 patterns, so you are not displaying all 24 bitplanes from each frame. I show from that file that you are only showing 18 bitplanes from each video frame. So are you only showing 6 bitplanes from R & G & B (for a total of 18)?
  • 0 in reply to Fizix
    Prodigy 140 points

    Hi Fizix,

    As per my understanding, the trigger output 2 sends a pulse before the start of the pattern(Figure 2-8, page 51, DLPC900 programming guide). Falling edge marks the beginning of the exposure so I used the falling edge. This worked for 400 patterns with pre-stored pattern mode.

    I think the buffer size is high enough as I am able to capture all 3200 patterns in pre stored pattern mode(400 patterns flipped and inverted). In video pattern mode, for just 48 bit plane patterns, It occasionally misses 1 or 2 bit planes.

    I also tried to run few patterns in pre-stored pattern mode and stop the run and shift to video pattern mode, then it worked for 1 HD image and its been repetitively shown for 120 times acquiring 2880 patterns but they are of same HD image(24 different patterns repetitive of 120 times). So I think it didn't change the display mode from pre-stored to video pattern mode.

    I am just running the batch file I created which posted it, so there are no setting file to send. If needed, I can redo and send it to you.

    Its total 24 bit planes, the batch file has it in hexal representation so basically 0x18.

    Regards

    Chaitanya

  • 0 in reply to Chaitanya Mididoddi
    TI__Guru 54705 points

    Chaitanya,

    Sorry,  I was  tired when I posted yesterday and should have noticed that this was 0x18 (not 18) - DOH!

    I looks like you are missing on average about 1 bit-plane per frame (slightly more).  Does it seem to be mostly the same bit-plane or random?

    Fizix

  • 0 in reply to Fizix
    Prodigy 140 points
    Hi Fizix,

    That's ok. No worries. Yeah. Its a bit random. Last time, I checked with 48 bit plane patterns. Sometimes it misses 1 frame sometimes it works perfectly. If I run 2880 frames, it misses 16 mostly. Sometimes 17.
  • 0 in reply to Chaitanya Mididoddi
    TI__Guru 54705 points
    Chaitanya,

    Do you have any reliable way to count output triggers on 2 (some scopes can count pulses) and see if there are missing output triggers?

    Fizix
  • 0 in reply to Fizix
    Prodigy 140 points

    Hi Fizix,

    Yes, I think the same. We will need to count the trigger output pulses using LabView interface. But currently we have put this on hold as I need to use imaging setup with pre-stored pattern mode. I will reply if count is working. But this may take a while.

    Regards

    Chaitanya

  • 0 in reply to Chaitanya Mididoddi
    TI__Guru 54705 points
    Chaitanya,

    I am going to mark this "TI Thinks Resolved". If you get back to it in the next two weeks you can re-open this thread. If longer, you can simply start a "Ask a related question" thread to continue.

    Fizix