P+ driving a recycled junked laptop LCD


alex
  • Alex salvages an old laptop display and manages to use the LVDS output of the Papilio Plus to drive it!

I had a broken laptop that was given to me and after it sat there gathering dust for a long time I decided to take the LCD apart since I had nothing to lose if nothing came of it. Once I exposed the LCD panel, I was pleasantly surprised to find a datasheet online with electrical, timing specs, even a pinout for the LCD panel, a QD15TL02 type which is a 15" panel with 1280x800 pixel native resolution.

The panel requires about 10V (5W) for the CCFL inverter and 3.3V (1.4W) for the logic, you can see below a 3.3V linear regulator I found in my junkbox bolted to a heatsink which I'm using currently do bring up the LCD panel. Additionally the panel is driven with four LVDS differential pairs, three for data and one for clock.

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Currently I have all the signals soldered to a small perfboard with a header that plugs into wing slots BH and AL. The reason I chose these slots is because I need differential signal pins and no single wing alone provides these.

Eventually I plan to make a small circuit board with a switch mode regulator that will fit in the corner seen in the picture above (the three screw holes). The PCB will have a barrel connector for power, a small pot for adjusting the brightness and a HDMI connector for the signals. Below is an eagle board I submitted to Batchpcb the other day. The LCD panel is not HDMI capable but the HDMI connector is ubiquitous and ideally suited for passing the high frequency data signals required.

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On the right hand side above is a Pap wing with an HDMI connector which I plan to use to connect to the LCD panel but by reprogramming the FPGA to talk TMDS, that wing should be able to be used with any proper HDMI sink. I can't wait to use that wing to try out Mike's Dvid_test on my HDMI monitor.

The ground planes in the picture above have not been rendered for clarity. I've already received the components from Digikey (in less than 2 days no less) but Batchpcb has been having issues for the last few days and I only just today managed to buy my design, now a few weeks waiting for boards to turn up :(

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