Python
Newbie level 3
Guys, I need some advice on interfacing a 2 x 16 HD44780 display to a PC via the parallel port.
In a nutshell here are the connections as supplied with the part.
LPT pin 1 to pin 6 (E) on LCD
LPT pins 2 - 9 to pin 7 - pin14 (DB0 - DB7) on LCD
LPT pin 17 to pin 4 (RS) on LCD
+5v to pin 2 (Vdd) on LCD
GND to pin 1 (Vss) on LCD
There is also a trim pot with the wiper going to pin 3 (V0) for contrast.
I've cut the end off a paralel cable and wired the display up according to the supplied info (testing each wire with a multi-meter) and whilst the backlight lights up there is nothing displayed on the display, not even solid blocks or anything. I downloaded an application called Smartie from h**p://lcdsmartie.sourceforge.net/ and that fails to communicate with the port (yes I have also downloaded the port95nt.exe too), regardless of the settings entered.
On searching the net I've noticed that there is some descrepancies in the wiring of the parallel port. Most show diagrams with RS (lcd pin 4) connected to pin 16 of LPT1 and RW (lcd pin 5) connected to pin 14. I tried this and still nothing displayed.
I'm open to suggestions as to what may be the problem. I'm running XP on the PC and I know that there are issues with accessing port directly under XP but thought this was restricted to serial ports. I have MS Virtual PC which runs windows 98SE and I've tried that but still no joy.
I know electronics can be a steep learning curve, but this has got me stummped.
In a nutshell here are the connections as supplied with the part.
LPT pin 1 to pin 6 (E) on LCD
LPT pins 2 - 9 to pin 7 - pin14 (DB0 - DB7) on LCD
LPT pin 17 to pin 4 (RS) on LCD
+5v to pin 2 (Vdd) on LCD
GND to pin 1 (Vss) on LCD
There is also a trim pot with the wiper going to pin 3 (V0) for contrast.
I've cut the end off a paralel cable and wired the display up according to the supplied info (testing each wire with a multi-meter) and whilst the backlight lights up there is nothing displayed on the display, not even solid blocks or anything. I downloaded an application called Smartie from h**p://lcdsmartie.sourceforge.net/ and that fails to communicate with the port (yes I have also downloaded the port95nt.exe too), regardless of the settings entered.
On searching the net I've noticed that there is some descrepancies in the wiring of the parallel port. Most show diagrams with RS (lcd pin 4) connected to pin 16 of LPT1 and RW (lcd pin 5) connected to pin 14. I tried this and still nothing displayed.
I'm open to suggestions as to what may be the problem. I'm running XP on the PC and I know that there are issues with accessing port directly under XP but thought this was restricted to serial ports. I have MS Virtual PC which runs windows 98SE and I've tried that but still no joy.
I know electronics can be a steep learning curve, but this has got me stummped.
