Sharp LQ043 LCD interface
I finally got my hands on the Sharp
LQ043 LCD display, the same display used in the playstation
portable. I got this display in a total deal with a special breakout
board that brings out all the connections from the display out on 2
pinheaders. Onboard there are 2 low noise DC/DC converters (MCP1253-ADJ)
that provide 2.5V digital for the board, and 5V for the analog for the
display. A seperate backlight supply was made with the MC34063
switching converter.
First I attached the board to a small XC9572XL CPLD, just to check out
the clocking generation. I adapted the CRT signal generator from my VGA
projects and changed the timings to suit the LCD (do not forget to
change the sync polarity!, was stuck on that for a while).
Right away there was a problem noise on the display, there was a faint
shimmering. I first suspected the decoupling but after some further
enquiry it seemed that more ground connections where needed from the
breakout board to the breadboard. Plus the breadboard does put out lots
of ringing signals.
Warning! The LCD arrives with the cable flexed behind the LCD, if you
flex it too often in the straight position you picture will go, and the
right top corner will get hot! This seems like a bad connection and I
recommend not flexing or stressing the LCD cable too much to prevent
damage. I keep the cable angled so it is as much as possible in its
original position.
After tweaking the whole on the CPLD I wanted to see the display in its
full 24 bit glory and attached it to my Coolrunner CPLD board that has
a lot more I/O's and capacity for various effects.
here you can see the effect for a Xor pattern.
Effect for X*X+Y*Y
Verilog code.
Next step is to attach a RAM for a framebuffer, but that is for another
time.
Back
Last update at: 24-07-2007