HD44780 lcd with PIC and USB interface

fnmc · Post by **fnmc** » January 4th, 2007, 12:14 pm

Hi! I'm new in this forum.. I really enjoy lcdsmartie and I got it working with my strange lcd configuration..
My laptop doesn't have any LPT port so to have an Hitachi parallel LCD, i had to interface it through USB. Actually the hard work is done by a small PIC controller with a TTL interface attached to a serial->usb converter..
My problem was this lcd is fully HD44780 compatible but all lcd softwares out there expected it to be plugged into a parallel port and not into a com port!
Thanks to your "test driver", i could get it working with small effort. Now i'm guessing if it's possible to improve the test driver to support special characters or if it's possible to slightly modify the original hd44780 driver to support com port too..

Thx anyway, Alberto..

Post by **mattcro** » January 4th, 2007, 4:52 pm

The problem is there's no standard/easy way to plug an LCD directly into a COM port, unlike the parallel port where we can just use the data lines for the data and some LPT control lines to do the handshaking (read/write/enable etc).

Smartie does support Matrix Orbital and Crystalfontz displays, which have an intelligent controller like your PIC circuit and connect to the serial port or a USB->serial adapter. If you can program a PIC to emulate the Matrix Orbital controller, you have a self-contained, USB or serial connected LCD that will work natively with lots of software.

There are several projects on this forum that do exactly this using PIC or AVR micros. I developed one using a PIC16F628, X7JAY7X made a similar one at the same time and there are a couple of others. Do a search for "backpack", "matrix orbital", "pic" etc. There are schematics and PIC code.

Are you using something like the FTDI USB->RS232 cable? They are ideal for projects like this because they can also provide the power supply for the PIC and LCD (except if you need lots of current for a backlight).

fnmc · Post by **fnmc** » January 4th, 2007, 5:11 pm

I've bought this lcd already wired so I don't know exactly how it was made.. But i'm sure that the serial converter is the FTDI.
Also i'd like to know if you could teach me how to reprogram mi pic! I'm not kind in electronics so if i mail you all the schematics, can you tell me how to turn it into a matrix orb display? Is this possible without changing the wiring?

Thanks, Alberto.

Post by **mattcro** » January 4th, 2007, 9:39 pm

I just assumed that you had developed the PIC interface. Did you buy it as a kit (or ready-made)? Where from?

The serial-to-LCD interface that I designed is similar to X7JAY7X's and takes advantage of specific features in the particular PIC chip we both used. It may be possible to modify your circuit and reprogram the chip, so tell us all the details.

If your LCD and controller is compatible with the Seetron controller (aka "backpack"), you can use Smartie's Seetron driver, which is only in new versions and I think is still in development.

I just discovered another reference to LCD Smartie in this article on hackaday.com with uses an Atmel AVR to do Crystalfontz emulation.

fnmc · Post by **fnmc** » January 4th, 2007, 9:59 pm

I bought it on ebay and was readymade! It has a pic16f628a controller! If you tell me your email address i will send to you the schematics (which are in italian, i'm sorry)..

Is that ok?

Post by **mattcro** » January 5th, 2007, 1:44 pm

@fnmc: I have sent my email via PM

Who is the ebay seller? I'm curious to find out what sort of interface it is and if it is compatible with other designs.

_X7JAY7X_ · Post by **_X7JAY7X_** » January 5th, 2007, 7:33 pm

Matt if you think that a new firmware will be easier let me know. I can rearrange my ports and recompile mine in a matter of minutes for the 628A. The only thing with my firmware is that D4-D7 (lcd) has to be on the same pic port. It cannot for example have D4 on pin A1 and D5 on pin B1.

It also depends on whether the pic is socketed, board has an icsp header, or a bootloader.

Post by **mattcro** » January 5th, 2007, 9:06 pm

Thanks for the offer, Jay. I don't know any of the details yet. It may not be easy to reprogram depending on schematic and board layout. If it's a socketed chip it's not too bad, but ICSP could be fiddly. It sounds like fnmc (Alberto) doesn't have any PIC tools anyway, maybe little electronics experience?? If the command set is sensible, it's probably best to just stick with the existing setup.

fnmc · Post by **fnmc** » January 5th, 2007, 11:47 pm

Sorry, i had no time to mail you all the schematics! I'll do it ASAP.. Anyway i never programmed a PIC and i'm not kind in electronics but i can learn very quickly! I know other computer languages very well (java, c, vb, etc..) so it won't be a problem! Just tell me what i need and where to find infos, tutorials&co.!

Alberto

Fast351 · Post by **Fast351** » March 20th, 2007, 7:03 pm

Hopefully you guys are still watching. Check this thread:

http://forums.lcdsmartie.org/viewtopic.php?t=1266