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DLPC3479: RGB LED Current PWM Limitations

Koichi Kadowaki
Prodigy 100 points
Part Number: DLPC3479
Other Parts Discussed in Thread: DLPA3005, DLP4710EVM-LC

Tool/software:

When I set 00h to 5Bh using the DLPC3479's "Write RGB LED Current PWM (54h)" command and read it back, the set value becomes 5Bh.
Why is that?
The DLPA3005 manual says, "For proper operation, the LED current must be at least 5% of ILED_MAX." So is it not possible to set a value lower than 5Bh, or 00h?

  • 0
    TI__Genius 12035 points

    Hello Koichi-san,

    Thanks for reaching out through E2E!

    Could you share the error you are seeing? Are you utilizing the GUI and which version of GUI and software?

    The DLPC3479 controller Software Guide this address has 6 bytes of parameter data and I can't tell what's happening, an image will definitely help here.

    The GUI has caps on how low and high the LED current can be set to, we do this to keep the user within recommended operating ranges and not damage the system.

    Best,

    Aaron   

  • 0
    Prodigy 100 points

    Dear Aaron-san,
    Thank you for the reply.

    We are testing two types of boards: DLP4710EVM-LC and our development board.
    DLP4710EVM-LC uses a GUI, and our development board is controlled from the host via I2C.
    I have attached the GUI, software version and execution results.
    The results are the same with our development board.

    Best Regards,
    Kadowaki

    GUI, software version

    Set 0, 90 (0x5A), 91 (0x5B)

    Get Rgb Led Current

  • 0 in reply to Koichi Kadowaki
    TI__Genius 12035 points

    Hello Koichi-san,

    Thank you for sharing the error this helps a LOT!

    This is correct, when you perform a Get and it is outside the spec limit of the parameter we've defined for our EVM is suitable, it will default to the lowest offered. In this case, you set Red to '0', Green to '90' and Blue to '91'.

    If you want to bypass this parameter, yourself and other customers can directly send a command through API but we do not want customers to accidentally damage this system hardware. We also keep it within an operable range because lower LED current produces instability and would raise additional questions.

    I notice you are running with 8.3.0, I would recommend you upgrade to 8.4.0 firmware  from the selector tool here.

    Best,

    Aaron 

  • +1 in reply to Aaron Black
    Prodigy 100 points

    Dear Aaron-san,
    Thank you for the reply.
    Best Regards,
    Kadowaki