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turn off illumination

Chi Zhou
Prodigy 70 points
Other Parts Discussed in Thread: DLPC200

Hi, Sanjeev,

I have another question regarding turning off the display. In my application, the procedure is exposing a gray scale image for some seconds, then exposing black image.. To save the power, in the second second step, I want to turn off the LEDs instead of exposing black image. I checked the API functions, to my understanding, there are at least 3 ways to turn off illumination:

(1) DLP_LED_SetLEDintensity(0), I tried this, it can shut down the LED

(2) DLP_Display_DisplayStop() can also shut down the LED, but after this, I check the intensity using DLP_LED_GetLEDintensity, the intensity is not changed, even the device is not shining the image.

(3) DLP_Display_ParkDMD(), I'm not sure what this function really do. But it also turns of the illumination. My guessing is it stopped the DMD flipping. Am I right?

Could you explain a little bit of the differences?

Thanks!

Chi

  • 0
    TI__Mastermind 30875 points

    Hi Chi,

    (1) This will basically command the LED driver to not drive LEDs or drive them with 'zero' current.

    (2) The LEDs turned ON/OFF with in combination of two parameters, one is called LED_Enable signals (or strobes) and then LED Current setting, both parameters has to be active to turn ON the LEDs. So in this case even though LED driver configured to drive LEDs with a non-zero current level, since you have called display_stop, the LED enable signals/strobes are not going. This will cause LEDs not turn ON. Effectively end result is same as (1) .

    (3) Yes you are correct.  This better method because next time when you want to turn ON it will be fast, the previous two API calls require DLPC200 to send command to LED driver. In PARK/UNPARK everything happens within DLPC200.

    Regards,
    Sanjeev

     

  • 0 in reply to Sanjeev
    Prodigy 70 points

    Hi Sanjeev,

    Thanks for your instant reply, one more question, when I use PARK function, the LED intensity will not be changed, right? Should I turn off the LED also if I want to save lifetime of the LEDs and also decrease the heat generated by the system. In our application, only around like 1/5 of the period time the system projects gray image.

    Best,

    Chi

  • 0 in reply to Chi Zhou
    TI__Mastermind 30875 points

    Hi Chi,

    Yes you are correct, with the PARK function, the LED intensity remain untouched. You don't need to turn of LED with API, just using PARK and UNPARK function is sufficient.

    Regards,
    Sanjeev

     

  • 0 in reply to Sanjeev
    Prodigy 70 points

    Hi, Sanjeev,

    Thanks, now I'm clear.

    Best,

    Chi