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DLPC900: Duty cycles

Part Number: DLPC900
Other Parts Discussed in Thread: DLPC910, DLPC410

Hi all,

In principle I am worried about the same issue like "Peter" here: e2e.ti.com/.../620500 To me it seems that there was a misunderstanding. On the one hand there is the IDLE mode of the DMD (DMD Lightcrafter 9000 from Texas Instruments) which turns on/off a 50/50 duty cycle of the mirrors (so switching between state -12deg and 12deg) but I think Peter is worried about something else.

I use the pattern on the fly mode and 1 bit patterns. By uploading one image and defining infinite repeat of the sequence, the DMD displays a static image (100/0 duty cycle). I used a photodiode to observe the intensity of the beam leaving the DMD and I find that there are intensity variations each 105 microseconds (basically the same thing that Peter mentioned). I think that the mirrors are released each 105 microseconds such that they are in an undefinded state (oscillating so they are neither at +12deg nor at -12deg). One can observe the same behaviour when the DMD switches between a black and a white image (mirrors are in -1, than they are released and oscillate, after that they are in +1).

Is it possible to turn off this 105 microecond clock pulse?

Best Carl

  • Carl,

    The DLPC900 is a based on a customization of one of our video controllers.  The advanced firmware allows you to do quite a bit with the system, but the underlying core has a base reset cycle of 105 microseconds.  At this time we do not have a way to change this.  

    The DLPC410 and DLPC910 controllers give the type of control you are looking for with the DMD's that they support.

    What are you wanting to accomplish that is impeded by the brief perturbation of the mirrors during resets.

    Fizix