Problem with HD44780 on USB cable convertion

burn886 · Post by **burn886** » January 5th, 2008, 10:15 am

Hi! Sorry for my bad english..but I have a problem with my LCD panel. I've got a HD44780 on LPT port, now I buy an adaptor LPT-USB but it doesn't function...LCD Smartie don't find driver! How can I resolve it!? thanks

Post by **caesar** » January 5th, 2008, 7:57 pm

Sorry to bring bad news to you but LPT to USB adapters don't work. They can be used just for printers, not for connecting a LCD.

burn886 · Post by **burn886** » January 6th, 2008, 11:19 am

thanks!

garrettgriess · Post by **garrettgriess** » February 1st, 2008, 8:58 am

I read that using a true PnP parallel / usb converter like this one: http://shop.vendio.com/dixmaxx/item/933 ... 1201692671 it would be possible to do this. Is there any truth to that before I waste $10 bucks?

Thanks,
-Garrett

Post by **mattcro** » February 1st, 2008, 12:56 pm

Several people have tried USB>Parallel adaptors and I don't think any worked, so this one probably won't either. The problem is that Smartie (and other software that uses the port in the same way) needs to have direct access to a real hardware I/O port at a defined address. It cannot work with a "virtual" parallel port. Printers are a different story, because Windows handles all the port trickery internally and programs simply say to Windows "print this data". There is a standard connection scheme for parallel port printers (that's what the port was designed for) and these adapters use that scheme. There's no such standard for connecting LCDs.

If you need a parallel port interface for an LCD, you have to get a PCI card port. However, I'm not sure if these are properly supported under Vista - best to check first.

It's becoming harder to use the parallel port these days, so if you can, get/use a USB or serial LCD.

Post by **caesar** » February 1st, 2008, 1:33 pm

burn886, have a look at this http://forums.lcdsmartie.org/viewtopic.php?t=1540

Maybe you can get started with USB and lcdsmartie!

Post by **mattcro** » February 1st, 2008, 7:05 pm

Good call, caesar. That's probably the easiest way to connect an LCD to USB without using the parallel port, and not too expensive either. It can even supply backlight power from the USB port.

garrettgriess · Post by **garrettgriess** » February 1st, 2008, 8:28 pm

I hadn't seen those. It looks easy enough. Thanks guys.