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DLPC900: What is the state of the DMD mirrors after parking them, then powering down the system?

Lesser Horned Owl
Prodigy 140 points
Part Number: DLPC900
Other Parts Discussed in Thread: DLP9000,

Hi,

I have designed my own boards that are the equivalent of the DLP9000 EVM (2x DLPC900's plus DLP9000 DMD). Using the TI Lightcrafter GUI, I park the DMD mirrors by going to the System Settings tab, checking the "DMD Park" box, and clicking "Set." I observe the DMD mirrors going to a uniform state. But when I power off the boards, I see that the DMD mirrors go to a *different* state. The mirrors are still all in the same position, but are definitely different from the state I observe when I send the park command.

It is my understanding that the mirrors should be parked before a power down event. If the mirrors are parked after I send the command, what state are they going to after I power off?

After the DMD park command:

After DMD park command

After power-off:

Power off

I was careful to turn off white balance and ensure that the aperture and shutter speed on my camera were the same for both of these images. This issue concerns me because what if the mirrors are not actually left in an unparked state when the system is not in use?

One other note: After I send the DMD park command, I click "Get", and the "DMD Park" checkbox becomes unchecked. Is there a bug with the GUI, or are the mirrors actually not parked?

After Set:

After Get:

DLPC900 firmware version is 5.0.0. LC GUI version is 4.0.1.

Thank you for any assistance.

  • 0
    Prodigy 140 points

    I am correcting myself from the above. I was confused about the GUI between DMD parking and going into Power Standby mode. I understand that I need to go into Power Standby mode before powering off the system.

    I see that setting Standby mode via GUI puts the mirrors into the same state as they appear when the system is powered off. But the question remains, what is the state that I see when I use the GUI to park the mirrors?

  • 0 in reply to Lesser Horned Owl
    TI__Expert 3040 points

    Hi Hanson,

    Thanks for sharing DMD Images and GUI Screenshots.

    Parking the DMD will put all the mirrors into flat state. The parked position of the micromirror is not a latched position and is therefore not necessarily perfectly parallel to the array plane. Individual micromirror flat state angular positions may vary.

    Any running pattern sequence should be stopped before putting DMD into Parked state or Moving to power standby.

    Please follow below procedure and update us the result.
    1.  First stop the pattern sequence already running. Go to Pattern mode page and click stop. "Sequencer Running" status will be unchecked. 

    2. Now Park the mirrors. " DMD Micromirrors Parked" status will be checked. 

    3. At this stage, getting Park status reads properly.

    Moving to Power Standby mode is recommended when DMD is not active for long time.

  • 0 in reply to SHIVAKUMAR R
    Prodigy 140 points

    Hi Shivakumar,

    Thanks for your response. I do see the difference now. I wasn't stopping the pattern sequencer before trying to park the DMD. So, what was I seeing on the mirrors, then (first picture)?

    Hanson

  • 0 in reply to Lesser Horned Owl
    TI__Expert 3040 points

    Hi Hanson,

    That could be all the mirrors in off state. 

  • 0 in reply to SHIVAKUMAR R
    Prodigy 140 points

    Hi Shivakumar,

    I see. I guess that it's best to pay attention to the "DMD Micromirrors Parked" checkbox to see whether the mirrors are actually in the parked state.

    Thanks for your help!