Three LCD questions

[Mikael]

I´m building this one
http://www.syscall.de/ebay/datasheet_20x4.pdf (small)
http://www.syscall.de/ebay/Anschlussplan.pdf (small)
But there is some wierd things there in my opinion

First the resistor. Only 5.6ohm? Just wondering if that can be right sence in all other LCD:s I´ve seen it has been much higher.

Second, pins 18 through 25 to GND I haven´t seen that before either.

Third what do I do with the wires in the printer cable that I don´t use, just isolate them? and what about the wire that is connected to the metal casing (the caseing around the pins) what do I do with that one?

I hope somone can help me out with my questions

 

[rm.o]

Pins 18-25 are the ground pins for the parallel port, it's not uncommon to use all of them when hooking something up. Most likely 5.6 ohms is the correct resistor value for that lcd, if you're unsure just turn the 100 ohm trimpot to it's maximum resistance before hooking it up to the 5v source, and adjust it for the contrast.

As for the other wires in the printer cable, you can just insulate them and they'll be fine. The wire running to the casing is called the chasis ground, it grounds itself to your case, which is grounded to the powersupply. Generally I just leave it unconnected, but if you like you can just connect it to the metal surround of the parallel port connector, you should be able to solder right to the connector.

 

[Mikael]

ok then things seem to as they should. I just wanted to make sure so that I don´t destroy it.
So thanks for the help .