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DLPLCR4500EVM: External PWM to drive LEDs and Python interface

Part Number: DLPLCR4500EVM
Other Parts Discussed in Thread: DLPC350

Dear all,

I am looking for the easiest way to do the following:

Showing a given pattern via Video Mode (microHDMI) and turning the LEDs on with TTL signal from a microcontroller.

Currently I am using an HID interface to the LightCrafter 4500, however, that is kind of slow if I need sub-ms precision.
There, I just turn LEDs on and off by setting the power. 
Ideally, I would like to have an Arduino or Micropython to turn the LEDs on-off by a PWM signal.

Further, if someone has an easy library to upload my (binary) images to the LightCrafter without using the GUI,
but rather a Python library, I would be very happy.

Thank you so much.

  • Hi Anki,

    Thanks for your question and welcome to the forums. Right now TI does not have available exactly what you are looking for but others may have developed the SW to do this, so I would recommend seeing if the community can chime in.

    In general, the DLPC350 controller is designed to control the LEDs by itself and you shouldn't need to handle things at the PWM level, a simple command should suffice. Can I ask what your application is and get a little more detail on what your goals are for turning on/off the LEDs?

    Thanks,
    Paul
  • Hi Paul,

    thanks for your prompt answer.

    My problem is, that showing black still lets some LED light through, so it is not completely dark. My application is Neuroscience based, so I want to have complete darkness, and then for a given amount of time (e.g. 100 ms) the desired (binary) pattern with a distinct power. And ideally, assessed by a custom written Python script.

    My desired workflow woud be:

    a) Upload image(s) to LightCrafter (up to 5 lets say)
    b) Set active LEDs and their powers
    c) Show image X (have DMD in proper position), but shut down LEDs
    d) At time point Y turn LEDs on as set in b) for a given amount of time.
    e) repeat c) and d) until experimenter stops experiment.

    I do not need any intensity modulation (which could be handled by DMD), nor RGB patterns independently.
    So one DMD pattern would fit all LEDs at the same time, no interlacing of colors.

    Thank you,
    anki

  • Hi Anki,

    In light of what you are looking to do, I would recommend that you spend a little time familiarizing yourself with the programmer's guide for the DLPC350. www.ti.com/.../dlpu010f.pdf

    There are commands there for controlling the LEDs and you could write a python library to control the Lightcrafter using I2C or USB commands and accomplish what you are looking for.

    In general, I would say that the current implementation relies on the Off-state of the mirrors to completely block all light from the output, but the optics on the EVM are not perfect and therefore have a little leakage.

    -Paul