Another Keyboard Encoder

I have made a serial keyboard interface I would like to share with others. I would like to know what eles this project could use to make it better.
Please see the attached PDF file
Thanks

Serial Keyboard.pdf (350 KB)

I’m a little confused - what is the purpose of using the LCD library here?

#include <LiquidCrystal.h>
// initialize the LCD library with the numbers of the Arduino pins used
LiquidCrystal lcd(3, 2, 4, 5, 6, 7); //LiquidCrystal(rs, enable, d4, d5, d6, d7)

Did 'ja a little favor here… cut the price in half by using one store instead of a bunch :wink:

Part Number Description Quantity Unit Cost Total
171969 IC,EDE1144,KEYPAD ENCODER DIP-18 1 $5.19 $5.19
169245 SWITCH,KEYPAD,16 BUTTON, WITH 8 PIN MALE HEADER CONN. 1 $9.95 $9.95
324962 CRYSTAL,4.000MHZ,HC49/US,20PF 1 $0.59 $0.59
97586 @RESISTOR NET,10PIN,330OHM,2%,
125mW,ISOLATED
10 $0.07 $0.70
267944 @RESISTOR NET,6 PIN,2.2K OHM
SIP,1/8W,2%,100PPM,COMMON
10 $0.07 $0.70
169288 PCB,BLANK,SNGL SIDED,PHENOLIC, 1 $3.95 $3.95
70755 HEADER,VERTICAL,REC,1RW,8cont .100 (2.54mm),FEMALE HDR RECPT 1 $0.45 $0.45
417682 LED,MOUNTING HARDWARE, LOCKING HEADER,HORIZONTAL 3-PI 1 $0.25 $0.25
Subtotal $21.78

Looks like a cool idea though! I could probably use something like this… plus, I haven’t used one myself, but according to the “bus” schematic, a resistor net would be a lot more efficient than using individual resistors… well, shoot, now I think it out, the 330-ohm one might need an “isolated” net instead, but the 4.7k one (2.2k here, since 4.7k wasn’t available but 2.2 should do just as well) is tied to ground so it should be perfectly suitable and simplify the PCB layout. :slight_smile:

edit: Updated list with 330 ohm isolated resistor net (5x 330 ohm isolated resistors)
edit: Here’s the part for 4.7k if you want to stick with 4.7k, it’s a bit more expensive: http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=276172&

CrossRoads, The only reason I used the LCD to display the output of the keyboard is that I designed this keyboard for my bench buss for my Arduino. It could be easily converted to serial.print(); Maybe it would make it simpler. Thanks for your suggestion.

KE7GKP, Thanks for your input. I have no intension on manufacturing and selling this. I needed a keyboard interface for my Arduino and did not find one to meet my needs. I just want to share this for food for thought.

FalconFour, Thank you for your time in helping me with better part selection. Do you mind if I work your price list into the document? I had no production in mind just a one or two time project. All of you guys are great in response.

Of course you can :) You'd have to make some adjustments to the PCB layout to make use of the resistor networks instead of single resistors, but it'd definitely make soldering easier. Just thought I'd help out with the parts a bit :)