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DLPC350 trigger timing

Other Parts Discussed in Thread: DLPC350, DLP4500

1) It appears that when the DLPC350 outputs a trigger, the pulse remains active (low) for the duration of the exposure although this is not necessary for the camera electronics. Our application requires a rapid succession of several exposures so we need to sequence the triggers as quickly as possible. For long exposure times, this has caused a problem for us as the inactive time between pulses is very short (<5ms) and may not be allowing the cameras enough time to prepare for the next incoming trigger. This has manifested as triggers being missed by our cameras. It would be great if there was a way to reduce the trigger width to the minimum required to initiate an exposure without remaining low for the entire exposure time.

2) We are planning to upgrade to cameras with capability for higher frame rates. Can you tell me if we have control over frame rate when operating in the pattern sequence mode rather than video mode?  We are presently operating at 15 fps and there is some small level of adjustment available, but can we push to 30 or even 60 fps?

  • Hi Ted,

    1) If inverting the polarity of the trigger will help, take a look at the discussion in the LightCrafter4500 user's guide (www.ti.com/.../dlpu011) section 3.3.4 Trigger Controls and the DLPC350 programmer's guide (www.ti.com/.../dlpu010) section 2.4.3.2.2 Trigger Out1 Control. You also have some control over the width since the rising and falling edge of the trigger can be adjusted as described in the documentation.

    You could also use trigger out 2 with the number of patterns per pulse set to 1. Note that this pulse is nominally 20 us.

    2) For 8-bit patterns, the DLP4500+DLPC350 can operate at 120 Hz.

    Thanks,
    Clinton