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DLP9000: Enabling DMD Idle mode leads to Sequencer Running and LEDs are ON

Part Number: DLP9000
Other Parts Discussed in Thread: DLPC900

According to the DLPC900 Programmer's Guide (Rev. E) Section 2.4.1.4 (DMD Idle Mode):

This mode enables a 50/50 duty cycle pattern sequence, where the entire mirror array is continuously flipped approximately every 105 μs between the on and off states. Whenever this mode is enabled, the LED Enable outputs are disabled to prevent illumination on the DMD.

I wrote a short test procedure, tracking the status and mode of the device operation after each command executed:

1. When the device is powered up, we start in the Normal mode, the sequencer is running, the default pattern is displayed in the pre-stored pattern mode:

2. Then I stop the pattern sequencer by sending the USB command 1a24 with data byte 0. The device responds as intended: no image is displayed. Only the 'dark' pattern is visible:

3. Then I enable DMDs idle mode (USB command 0201, data byte 1). At this point I expected no illumination. Instead, we got a really bright rectangle (assume, 50/50 duty cycle pattern).

The sequencer got automatically into running mode (!) and LED outputs are ON (!) which contradicts the documentation. 

4. Then the DMD Idle mode was disabled. The system returned to its previous state:

Surprisingly, the sequencer got stopped automatically.

Could you please commend on such a behavior which deviates from what was cited above from the programmer's guide, that the LEDs in DMD Idle mode are not OFF, and the sequencer gets automatically launched.

Should I provide additional information, please, let me know.

  • Hello Roman,

    Could you please provide the FW version (and GUI version) that you are using?

    I would use the Batch Command LED_ENABLE 0x0 to disable the LED's - Note this sets bit 3 to "0" so that it will actually disable using bits 2:0.  See § 2.3.5.1 LED Enable Outputs (page 34 of the Programmer's Guide - USB 0x1A07).  Please read back what Bit 3 is set to currently.  If it is set to "0" then it will ignore Sequencer control.  This may be why the LED remains on in DMD Idle mode.  If so, then we need to add a note to the Programmer's Guide that for this.

    Please let us know, the result.

    Fizix