Using 14-pin LCD with 16-pin LCD Backpack??

[john3exonets]

All,

Just got a number of I2C LCD Backpack's and found out they are looking for 16-pin LCDs....my are all 14-pin <Sarcasm>Conveniently, the backpack has no numbers on the interface pins</Sarcasm>, so you can tell which solder pad is for pin 1, and which one is for pin 14...so I can't even be sure I'm using the right pins. These LCDs work just fine with my Arduinos, so I'm thinking they should be able to work with the backpack...if I only knew what pins to use. Anyone know??

Thank you very much for your assistance
John

[adafruit_support_bill]

The backpack is designed for standard HD44780 character LCDs. Aside from the 18-pin RGB variants, character LCDs are pretty universally 16 pin devices. Where did you find the 14-pin displays? If they do not use a HD44780 controller, they may not be compatible with the backpack library.

This data sheet shows the standard 16-bit pinout. The tutorial shows how the backpack attaches to a display.

[john3exonets]

They are Optrex DMC16230 16 x 2 LCDs. They are HD44780 driven, or at least they respond correctly to the signals and work with the Arduino LCD library...I'm using several right now in some projects using a 4-pin bus. Here's a datasheet I found on the Internet (http://www.digchip.com/datasheets/parts ... 30-pdf.php) They are only 14-pin.

Thanks for your help!
John

[adafruit]

14 pin displays often just dont have a backlight - they'll work fine

[adafruit_support_rick]

The extra two pins are for the backlight. Your LCDs don't have backlights. Here's a picture of the backpack board layout, with pins 15 and 16 located. Just leave those empty and attach your LCD to pins 1-14.

i2cspilcd_pins.png (47.23 KiB) Viewed 816 times

[john3exonets]

Yep, that worked! Down to two pins to my Arduino now Thanks!