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DLPLCR6500EVM: Synchronizing DLPCR6500EVM lightcrafter 6500 evaluation module with external kHz source

Manita Rai
Prodigy 70 points

Part Number: DLPLCR6500EVM

Hello,

I have a DLP lightcrafter evaluation module (DLPCR6500EVM) that I am trying to trigger with an external 2.5 kHz source (I am trying to synchronize it with a pulsed laser). The goal is to switch the pattern for each laser pulse, rapidly cycling through all 400 patterns in memory on indefinite repeat, but I am not able to do so.

I have set the exposure time to be 210 us and the dark time to be 0 us. I know that there is a 105 us delay between the trigger and when the pattern appears on the DLM. So, there is 315 us from trigger to completion of the pattern, allowing 85 us of dead time until the next trigger. However, I am not able to get the device to trigger stably. In other words, the pattern does not change with every trigger. Instead, it seems almost random when the pattern will change despite the fact that it is receiving a regular trigger.

The input into the device is a 2.5 kHz 3.3 V, 50% duty-cycle trigger locked to the laser that I am putting onto pin 2 of the input trigger. I am holding pin 5 high.

Is there something inherently wrong in how I have setup the trigger? I am using pattern on the fly mode.

Any help would be appreciated.

  • 0
    TI__Prodigy 145 points
    Hi and welcome to our e2e forum. It sounds like you probably have things setup nearly correct - all your timing numbers seem appropriate. A couple ideas....You may already have it in place, but for a 3.3V Trigger1 input please check that there is a jumper on J19 connecting pins 1 and 2. This sets the input supply voltage level for the trigger input receiver. Also please make sure your trigger source has a GND connection to J20-pin3 to ensure a proper voltage reference.
    I have briefly run this mode of operation in the lab today using a 2.5kHz input trigger but a much smaller number of patterns and it seemed to work and lock properly. As a debug assistance, you could try monitoring a trigger output with a scope as well. The trigger output should be locked at the same frequency as your input trigger but delayed by 105us. If so, then things "should" be working well. Then it is just a matter of verifying the pattern sequence. Have you tried a much smaller pattern sequence to see if that is successful?
    Lastly, do your patterns switch at the proper moment relative to the input trigger and is the issue is just the pattern to be displayed either inaccurately repeats or skips? I hope some of these ideas have helped.
  • 0 in reply to Bosun
    TI__Prodigy 145 points
    Hi - I have continued with more testing on our platform with your setup and we seem to be able to display our 400 patterns predictably using your setup parameters (2500Hz, 210us exposure time). Please let me know if you have any more information to consider or if you are still looking for ideas to enable our application.
  • 0 in reply to Bosun
    Prodigy 70 points

    Hi Bosun,

    Thank you for the suggestions. It seems like everything's working well now.