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I have read in this post that the insertion of the post vector is "recommended". Does this mean that problems with displaying patterns without clearing the DMD after each exposure are to be expected? I am trying to display a sequence of 1024 patterns (24-bit images flashed to memory) using an external trigger in variable exposure mode. However, I can never proceed past the first 48 patterns. When I trigger the 49th pattern, the DMD starts again from the first pattern. Is anyone else having this issue? Thanks.
Paul,
Thank you for your response. If I am not operating in video streaming mode but have my patterns stored in the flash memory, the buffer does not rotate automatically, correct? In that case, I assume that I would need to force the buffer to load the next set of patterns. How can I do this? I have read about the memory structure and the different trigger options but I have not able to figure this out. Basically, I'd like to be able to perform the buffer rotation (as in streaming mode) with a pre-programmed pattern sequence when all the images are loaded into flash.
Thank you for your help.
Hi Paul,
I'm using the provided LightCrafter interface (3.0.1) to first upload the images to flash and program the pattern sequence. I am using an external trigger to advance the pattern sequence.
The problem that I'm running into is that if I do not clear the DMD after each pattern, only the first 48 patterns are shown (apparently due to the size limit of the frame buffer). Further triggering causes the first 48 patterns in the sequence to repeat (despite additional patterns remaining in the sequence). If I clear the DMD after each pattern, then all 1024 patterns are shown properly. This returns to my original question which is whether or not clearing the DMD is required in order to cause the buffer to clear and refill as needed.
Thank you.
Hi Paul,
I tried extending the exposure and period to 500 ms but the same problem persists. I am using a DAQ to trigger the DLP externally. Here is a screen shot of the LightCrafter settings:
Is the 200 ms load time only required for the last (48th) pattern? Can the sequence be run at a higher speed for every other pattern?
Please let me know if you'd like me to provide additional information. Thank you.
Hi Danny,
Yes, the display of the patterns have always been displayed normally with the internal trigger. Is there a problem with the way I have implemented the external trigger? I have noticed that the "Black vector missing" icon turns yellow after I send and validate the sequence. But this doesn't happen when the internal trigger is specified.
Thanks for your assistance.
Hi Danny,
Thanks for following up. I am currently using a test panel for a DAQ from National Instruments as shown below. Unfortunately, I don't have access to a oscilloscope at the moment. I have connected TRIG_IN_1 to a digital output pin which I can manually flip by clicking the switch icon between 0 and 1 (see screenshot below).
I have tried varying exposure/period values (from 100 to 500 ms) and slowly setting the trigger so there should be sufficient time for the pattern to load and display. But I still am not able to move beyond the first 48 patterns. At the 49th trigger, it simply starts again from the first pattern. Any insights about this?
Thanks.