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DLP lightcrafter 6500 input triggers in structured light mode

nathan klein
Intellectual 345 points
Other Parts Discussed in Thread: DLPC900

Hello,

I am trying to work with the lightcrafter 6500 in structured light mode in pre-stored images mode.

I would like to better understand the trigger in 1,2 functionality. As I understand I need to keep input 2 high to start the sequence and then use input 1 to advanced the pattern is that correct? does input 2 has to stay high for the entire sequence ? 

In the documentation of the DLPC900 section 7.4.1 it says 

"To synchronize a camera to the displayed patterns, the DLPC900 controller supports two pattern modes: Video
pattern and Pre-stored pattern modes. In video pattern mode, the vertical sync is used as trigger input. In prestored
pattern mode, an internal user configurable trigger or a TRIG_IN_1 pulse indicates to the DLPC900
controller to advance to the next pattern, while TRIG_IN_2 starts and stops the pattern sequence"

while in the EVM documentation it says in section 1.2.3.2

"The trigger inputs on J20 are inputs from external devices to control the pattern sequence. While trigger

input 1 is high, trigger input 2 will advance the pattern sequence to the next pattern in the sequence on
every pulse"

which one is the correct one?

Also what does it mean "an internal user configurable trigger" ?

Could you be more specific about the restriction of the trigger (duration,frequency...) ?

Thanks,

Nathan Klein.

  • 0
    TI__Expert 6370 points

    Hi Nathan,

    I apologize about the delay, I wanted to hear back from the authors of the two documents you mentioned. The datasheet is incorrect, as the EVM documentation says, trigger 1 starts the pattern sequence by going high and trigger two pulses to advance each pattern in the sequence. We will correct this error in a future datasheet release.

    An "internal user configurable trigger" can be programmed through the GUI with a desired delay and exposure time, and will trigger the patterns to advance.

    The Device Functional Modes (7.4) of the DLPC900 datasheet has more information on trigger restrictions. If you let me know a little more about your application or your desired functionality, I might be able to answer your question more fully.

    Best regards,

    Trevor

    EDIT: The quote from the datasheet is correct, the quote from the EVM documentation (The LightCrafter 6500 and 9000 User's Guide), is incorrect. This correction will be made.

  • 0 in reply to Trevor Dowd
    Intellectual 345 points
    Hi,
    I have been working with the system for a while and I have noticed that in pre-stored pattern mode Input Trig 1 is used to advance the sequence while Input Trig 2 is used to start/stop the sequence.
  • 0 in reply to nathan klein
    TI__Expert 6370 points

    Hi Nathan,

    I apologize about the confusion, I was mistaken. To quote the DLPC900 Programmer's Guide on triggers (section 4.2.1): http://www.ti.com/lit/dlpu018

    • Video Pattern Mode (applicable when pattern data from RGB parallel port):
    – VSYNC used as trigger input.
    – TRIG_OUT1 frames the exposure time of the pattern.
    – TRIG_OUT2 : marks the beginning of each pattern start with 20us pulse. This can be selectively
    disabled for individual patterns.
    • Pre-Stored Pattern Mode (applicable for pattern data from flash):
    – TRIG_IN1 advances to next pattern, while TRIG_IN2 starts and pauses the pattern sequence.
    – TRIG_OUT1 frames the exposure time of the pattern.
    – TRIG_OUT2 : marks the beginning of each pattern start with 20us pulse. This can be selectively
    disabled for individual patterns.

    I have edited my previous response to avoid future confusion. The LightCrafter 6500 and 9000 EVM User's Guide will be edited to show the correct trigger descriptions.


    Thank you for following up with us, we appreciate the help! Please let me know if you have any additional questions!

    Best regards,

    Trevor