Thread: Okay, I'm stumped again....

re your backlighting, ar you sure you have a 5+ supply running to it? powering the LCD driver circuits does not normally power the backlighting led's.....


for the wiring, check and re-check, and ensure the plugin you are trying to use works with the wiring diagram you have used!

Also you are powering your LCD from external 5Volts or tapped off the PC's PSU and not the parallel port itself? I have seen a few guys trying to run their LCD off the power put out of the printer port, probably not too good an idea....

I would check your wiring. If done correctly it should work wiht any plugin compatible with your display. So far I have seen 2 diagrams for parallel port interface with a HD4470 controllers LCD's. One is specifically for a 40X4. ANother diagram is for the rest ( 40X2, 20X4, 20X2) Make sure you are using the right one.
Other than that, maybe you want to try on a diff computer and see if it works...

I have tested my 40X4 on 3 computers and it works fine on all of them. THe power shouldn't be from the parallel port itself...use the 5V coming off of your PSU.
good luck

Sounds like a power problem to me. Get a multimeter and check for voltage at all the major power points, as well as the backlight.

test your lcd with lcdprint.exe .
with this prog. you can print text in your lcd and see if it works corectly.
Peter3
peter.wendy@keyaccess.nl