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I had bought various types of LCD panels and figuring out how one of them works I had an idea to try to build a crude form of a photoframe out of it.
The panel is a controllerless 320xRGBx240 CSTN panel that only supports color pixels on or off, so black, red, yellow, green, cyan, blue, magenta and white are the possible colors.
Pretty much everything was built from scrap parts I had lying around: 20MHz PIC16F627 for the timing, 2x 74HC590 for address generation and some EEPROM chips used for BIOS on old PC motherboards for storing the graphics. (Also 2x 74LS373, 7406 & 74HC138 were scavenged to hack together a parallel port writer for the EEPROM chips.)
The EEPROMs have enough space to store four separate images which, when rapidly cycled, can be used to create a total of 125 colors from the default eight because the panel is sufficiently slow in changing the state of the pixels. The PIC is currently capable of updating the panel at around 85Hz. It still has a bit of flickering. Will at some point try clocking it with some ATMega.
The CCFL backlight, display and controlling logic runs from a single 5V powersupply.
While in the testbed.
Seems to be working so better build a dedicated controller.
Some sample images.
Total cost (not counting the PIC devboard and the EEPROM writer): ~20 euros.
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716
That's a marvelous piece of work; thanks for sharing your story. I particularly appreciate the challenge of using scrap parts, and getting a high-tech element to do things not intended by its designer.
Do you know if "normal" usage of the LCD panel includes pixel brightness control by duty cycle modulation, as you have done?
According to the manufacturer the display is meant to be used as an instrumentation panel to present simple graphics and values for some industrial device. Thus it only needs the simple primary colors.
I've tried some 4-frame animations with it too but they look a little bit blurry due to the slowness of the pixels.
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Simple digital photoframe
