2 x 20 lcd pin numbering issue

cookspyder · 07-07-2005, 10:41 PM

so i bought a lcd 24x2 with el light from allelectronics.com for 4 bucks. pretty sweet deal i think. just got it today and it looks great. but they have a cable already wired to it, a 2x7 ribbon cable. anyone ever work with one to attach to a computer and know the pin numbers so i can switch to parallel or anyone have any better ideas??

the back of the board with the socket connector looks like this

13 14
- -
- -
- -
- -
- -
- -
- -
1 2
the dashes being connector points im assuming that they numbered the pins
13 14
11 12
9 10
7 8
5 6
3 4
1 2

here is the exact model i have http://www.allelectronics.com/cgi-bi...107&type=store

thanks all in advance

marshallh · 07-07-2005, 10:50 PM

Heh, I bought that same exact LCD a while ago. I haven't used it, but I've used a 16x2 LED bl.

Anyway, your best bet would be to chop off the hanging connector end and use an ohmmeter to confirm the traces. As long as you keep the connector on, you'll save yourself a lot of trouble. I didn't particularly enjoy soldering 16 wires from a ribbon cable onto a 8x2 pin grid. This is something you can avoid.

KyleYankan · 07-07-2005, 11:03 PM

If you chop it, I'll send a few bucks for the other connector. I need one for my 24X8 LCD I have a mutilated IDE connector - it keeps messing up.

cookspyder · 07-07-2005, 11:28 PM

thanks i was already playin around with an ohm earlier but as u said soldering 14 wires deff isnt too much fun. im gonna head up to an electronics parts store to see if i can scrounge another ribbon cable up so i dont ruin the one i got.

happpyg · 07-07-2005, 11:33 PM

I have run a few of these through PIC chips but never through a PC, they all seem to be pretty standard pin configuration as below

1 - VDD
2 - VSS
3 - VO (Contrast)
4 - RS (Register Select)
5 - R/W (Read/Write)
6 - E (Enable Signal)
7 - DB0
8 - DB1
9 - DB2
10 - DB3
11 - DB4
12 - DB5
13 - DB6
14 - DB7

Hope that helps.

cookspyder · 07-07-2005, 11:36 PM

thanks happyg ill use that when i test the ohms i just hope the pins are in the order i believe them to be since they are not in a row style and dont look numbered all to well.

happpyg · 07-07-2005, 11:41 PM

No problems. I just had a look on the website where you got it from & it looks like there is a data sheet there for it. You might also need an inverter for the EL backlight, not sure if it would be included onboard or not. All the small character LCD's i've used have been LED backlit.

Good luck!

cookspyder · 07-07-2005, 11:48 PM

ya i think it needs an inverter too i havnt gotten to that point and i dont think illl need the el. ive looked over the spec sheets and there isnt a schematic for pin numbering (there is for what each pin does but it doesnt correlate to their positions on the board) so i just have to test each one i guess. lol now wont that be fun

marshallh · 07-08-2005, 08:43 AM

Well, if I remember right on my other screen, the connectors were
1 2
3 4
5 6
7 8
9 10
11 12
13 14

Its kind of confusing.

jcdillin · 07-08-2005, 09:11 AM

on the socket that is soldered to the LCD, just find the pin that has a square pad as oposed to a round pad, that will be your pin1, then it goes just like marshallh said

12
34
56
78

that should get you going