DLPDLCR2000EVM: Sometimes can't switch modes

Hi Philippe,

Thanks for the reply.  No, I don't cycle power.  I don't have any other convenient video sources to try, and the times when the DLP has switched to my video source (which displays a bar pattern), it has been setup for 640x430 display.  Thanks for suggesting a course for debugging.

Regards,

Scott

Hi Philippe,

This is most confusing, I'll explain.

My video generator generates vertical bars that are black and white by setting the 24-bit bus to 0x000000 or 0xFFFFFF.  I can choose the bar widths as well as frame width and height.  PCLK (pixel clock) is fixed at 20 MHz.  VSYNC is 8 lines wide, HSYNC is 8 pixels wide, both signals are synchronized to PCLK (all signals are active high).  Pixel data is output on falling clock edges.

With the projector freshly powered up (e.g. no I2C registers changed since power-up), I programmed register 0xB with 0 to select the external bus as input.  The projector acknowledges the change and begins displaying my bar pattern.  My default frame width is 640 pixels.  The projector shows "torn" bars at an angle I assume because it is trying to display a different frame width.  To determine what that width might be, I ran an experiment where I generate frames containing 100 pixel wide bars while varying the frame width from 200 to 1300 pixels.  As the width changes, the projector shows changing diagonal bar patterns.  When my frame width is 427, I see vertical bars.  For no other value of frame width are the bars vertical and stable.  I've attached a photo.  No matter what I adjust on the projector registers, I haven't been able to get rid of the blue stripe.  Note too that the projector is upside-down, so the bottom is the reference side.  The first photo shows one white bar 400 pixels wide, followed by a 27 pixel wide black bar (upside-down, so they start at the right-side of the image).  The second photo shows a full white screen.  The one-pixel wide vertical bar at the image's right side (left on the photo), is created by the projector.  As is the 1 pixel tall line a few lines from the bottom (top since it's upside down) of the white image.

Using that width I begin varying frame height.  As long as the height is 336 and above the frame is stable (although there is a little wobble to it).  Under 336 the frame flashes and displays colors  (mostly green and purple).

Thanks,

Scott