Lpc2000

Boris Kr\ufffdlik wrote:

>Hi Marko.
>I check pinout one more time, pinout is good (I think:
>Vdd=3V, Vlcd=5V(with capacitors), CS0=pullup to H,
>PS1=pullup to H, CD to uProc,  PS0 to
>GND;D1,3,4,5,6,7,RD/WR=GND; Vlcd -> Cap 1uF, and other
>pins (VB0+,-; VB1+,-) about LCD with capacitors 1uF)).
>I change Vlcd, first was 3V (same as Vdd) and I
>changed to 5V. Power consumation increase from cca.
>30mA to 110mA. I think, this is good, manual says
>2x60mA. Timing I check on scope, minimal timming at UC
>is in nano seconds, I work with micro sec.
>When I check pin VB0+,VB0-; VB1+, VB1- with scope =
>without signal, but not connect to GND. 
>Question: It is good ? I think not !!!
>Please check your signal on VC pins.
>Thank for you advise.
>
>  
>
If you have a scope, then the problem can be quickly traced down.  I 
would start out by verifying my understanding of the LCD controller 
registers.  For example, LCD have a number of parameters which need to 
be matched up against the display: dot-clock rate, lines per frame, 
frame rate, etc.

I would start out by calculating what the dot clock rate would be needed 
for the display.  Check the dot clock spec of the LCD spec.  Then see if 
you can program the controller to that dot frequency and verify on the 
scope.

Next is the number of dots per line.  Calculate dot-clock X number 
pixels per line.  This would give you the time interval of the Line 
Pulse (latch).  Verify that the Line Pulse rate is what is called out 
for in the LCD data sheet.

Next, calculate the Frame Pulse rate: dot-clock X number_pixels_per_line 
X number_of_lines.  Check the this time against what you see on the scope.

Finally, check the data line feeding the display, you should see 
constant data flowing out the LCD.  Assuming of course that you've put 
some data into the DMA / Frame buffer of the LCD controller?

Try clearing the LCD Frame buffer of data (all zeros), look at the data 
pulses going to the display. Then, fill the LCD Frame buffer with ones, 
did the data stream change dramatically?

If all the above are correct and reasonable values (+/- 10%) then take a 
real hard look at the electronics.  Many LCD displays will require a 
specific power on sequencing of the power supply to them.  If you 
violate this powerup sequence you run the risk of "freezing" the 
crystals within the display and they will not move for you.

An LCD is a dynamic device.  The crystals are in constant motion, think 
of it as an acrobat doing cartwheels.  if you hold these crystals into a 
single for too long, or jam them into position, they will freeze in place.


I've always found that if I cannot find out what is "wrong", prove what 
is "right".

Regards,

TomW


-- 
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net, http://cyberiansoftware.com
"Windows? No thanks, I have work to do..."
----------------------------------------------------