LCDInfo.com

Ok.. I´ll try these pins.

Another question: You´re linking pin VDD to pin 4 of Parallel port right? My parallel por is old 5 V. So.. I have for this specific pin to have a proper source, right? A 3,3V source. But what current does it need to supply?

Best Regards,

_________________
Henrique Vilela
rickonvb@yahoo.com.br

The display propably doesn't need much current at all, but as you have a 5V parallel port you need to buffer all the signals, including VDD.

Ok.. so.. I don´t need to have a 3.3 Source? The display can handle a 5V VDD? Thanks.

_________________
Henrique Vilela
rickonvb@yahoo.com.br

NO, the display CAN'T handle 5V. That's why you need to buffer it. Like in the schematics at the beginning of the thread. If you just use 5V directly you'll kill the display.

Got it!
But what about all the other pins? Do they work on 3.3V or 5V?

Thanks once again!

_________________
Henrique Vilela
rickonvb@yahoo.com.br

Every signal/voltage is 3.3V.

I couldn´t make it work yet...
I don´t know if it´s the program I´m trying...

I tryed the schem:

DISPLAY - LPT
RES - 3
VOUT - (Cap - 18 )
GND - 18
SCE - 18
DC - 2
SDIN - 1
SCK - 14
VDD - 4

What program should I use for this pins schem?

Best Regards,

Henrique

_________________
Henrique Vilela
rickonvb@yahoo.com.br

With that connection (and parallel port configured to the standard 0x378 address) this should give visible results if everything is ok.

http://oms.wmhost.com/lcd/pcd8544.zip

(Quits with esc)

Zee.. here´s the measures I´m getting from the pins in relation to the GND pin (18 ) after a few seconds:

Display ; LPT ; [V]
RES ; 3 ; 1.55V
VOUT ; CAP(- Pin 18 ) ; 0.10V
SCE ; 18 ; 0V
DC ; 2 ; 1.4V
SDIN ; 1 ; -0.10V
SCK ; 14 ; -0.30V
VDD ; 4 ; 1.36V

I have no idea of what is going on with these levels...
I´m using 3.3V Zeners and 1k resistors. I also am using 0.5uF capacitors (each is .5uF).

Any ideas!? I guess my lpt bus is 3V3 and not TTL as I thought. When a pin is active "1", the voltage is + -3.88V.

Best Regards,

Henrique

_________________
Henrique Vilela
rickonvb@yahoo.com.br

Well, if you get around that 3.3V from the port pins without anything connected (and without any LPT-accessing programs running) then it should be the newer 3.3V type port and you can wire the display directly into it without resistors/zeners.

I´m using Windows XP. Does this program work with it? I´ve been told that it´s hard to work with LPT under WinXP.

I´m still trying but I don´t think that the 3.98V I´m getting from the LPT is 3v3. Could it be?

Best Regards,

Henrique

_________________
Henrique Vilela
rickonvb@yahoo.com.br

The short testprogram I posted is made to work with WinXP.

You could try first adding a regular diode (1N4148 for example) between pin 4 and VDD to lower the voltage a bit.

I have built an interface board according to the schematics posted by Kalamake, but am having serious issues getting it to work. All test programs posted on this forum fail to display anything. I am confident that I have built the board correctly, but I need some guidance getting software to work with the screen.

Thank you in advance