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LCD_wanted Guest
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640x480 LCD old LAPTOP |
Posted: Thu Nov 04, 2004 3:13 pm |
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Does anybody see any project how without specially chip driving
LCD 640x480 , or any link's about this theme? |
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LCD_wanted Guest
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LCD |
Posted: Sat Nov 06, 2004 8:36 am |
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I found LCD and buy it with old LAPTOP (LCD - LQ9D011), and
find project with use this device for Video Card that is
http://www.maltepoeggel.de/html/tft2pc/
But not English, and I dont understand how use interface with that LCD
PLEASE ANSW.
Can I connect this LCD to PIC.
How send to this LCD pixel with coordin. X=10,Y=10, and Yello Color //as sample |
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Mark
Joined: 07 Sep 2003 Posts: 2838 Location: Atlanta, GA
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LCD_wanted Guest
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To Mark |
Posted: Sat Nov 06, 2004 11:09 am |
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Mark thanks.
Please answere else one Q. interface C1 15PIN and no DATA IN for choosing coordinate of putting pixel. Only Color.
Why? |
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Trampas
Joined: 04 Sep 2004 Posts: 89 Location: NC
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Posted: Sun Nov 07, 2004 7:32 am |
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The way the LCD works is that it has a horz and vertical sync signal and then a pixel clock. So when the vertical signal goes high the display pixel counter moves to top of screen. When the horz sync goes high the pixel counter moves to start of line. So you this sets your pixel posistion to top left corner of LCD. Now each cycle of the dot(pixel) clock will read the color inputs and draw that pixel on screen. When the current line is done the horz sync will go low and then go high again to indicate next line.
So basically to get a 60Hz refresh rate every 1/60th of a second the entire screen needs to be redrawn. So if you have 640x480 pixels this means the slowest your dot clock could be would be over 18Mhz. In reality your dot clock will need to be faster to account for inactive periods of the hsync and vsync signals.
To answer your next question, no the PICs are not fast enough to generate these signals, you can use an FPGA or CPLD.
Trampas |
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LCD_wanted Guest
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Thanks |
Posted: Sun Nov 07, 2004 12:55 pm |
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Now I understand (better use passive LCD )
I never used FPGA or CPLD, but maybe with
dsPIC 30MIPS really do that? |
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Trampas
Joined: 04 Sep 2004 Posts: 89 Location: NC
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Posted: Sun Nov 07, 2004 2:36 pm |
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The dsPIC can not do it either. Think about it...
You need to update a pixel every clock at about 18Mhz, 256 colors you would have a byte per color. Therefore to buffer the image you need 307Kbytes of SRAM. Then you need to read the SRAM and spit out the color data, so you have maybe one or two clocks of the 30MHZ dsPIC to do this. Plus you need to have some way to write the data into the SRAM.
Trampas |
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LCD_wanted Guest
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