Ecran Sharp LQ084V1DG21/en
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Sommaire
Presentation
These are LCD sceens manufactured by Sharp, with the following specifications :
- Resolution : 640*480
- Diagonal : 8.4"
- Colours : 18bits (6 bits per channel R G and B )
- Interface, timings : VGA-like (digital)
- Clock Frequency : 25MHz
- Power : 5V
Some of those screens available at the LOG include a touchscreen.
By measuring the voltage between the electrodes of the touchscreen, for example using analog inputs (ADC) of an Arduino, it is possible to locate
the X/Y position of a finger touching the screen.
Documentation
Official Sharp website (alas with time, such hyperlinks become obsolete)
Local copy on LOG server
Usage
The trick with these screens, is that there is no controller nor memory/frame buffer on board, which means that we must present each pixel colour at each pixel clock. Also, unlike VGA screens, the pixel interface is purely digital, so easier to drive by a digital device (no need for an DAC). Thus, these screens can be driven easily with a FPGA like the Papilio card because they can run designs operating over 100MHz. User Quicky and a427 developed such a driver ( maybe online someday ? )
Would be interesting to try and drive them also with Nucleos microcontroller cards.
Those screens have some exotic connectors and must be used with some ultra-thin flat ribbon, like those used for Raspberry Pi. A specific "LCD wing" for the papilio has been designed with Eagle software long ago by Giovanni (design files to be put online around here someday ?)
Demos
- One FPGA demo has been done by a427 with a papilio Duo driving LCD sharp screen
Design is available on github https://github.com/nsauzede/vga_generator/blob/lcdwing/vga_text_p2_lcdwing
