Puzzle

Link774

Hi folks,

I came across an interesting puzzle on·LambdaMOO a while back (text based game, telnet to lambda.moo.mud.org:8888) and wanted to try to reproduce it using a microcontroller. I am completely new to microcontrollers, so I was wondering if you could provide any guidance on what I need to get this done.

Here's the description of what the puzzle looks like:
"The mind bender has a display showing four words, and underneath each word is a knob. You can push, pull, twist, or smack each knob, altering the display. The goal is to make it read 'one true beautiful poem'."

The maximum length for each of the four words is 8, 10, 13, and 13, so including spaces I'd need a display that can show 47 characters (ideally on a single line). The 4x20 Serial LCD looks pretty good, I guess I could put each word on its own line and arrange the knobs along the side.

The knobs I'll probably have to build, since I doubt there is any kind of switch that fits that characteristic. Each knob is like 4 switches/buttons, so I guess I'll need a total of 16 i/o ports plus a serial output for the display.

So I'm thinking the 4x20 display and one of the Basic Stamp starter kits (which?). What do you think? Let me know if you need any more info

Thanks!
Link774

Mike Green

I've seen single "knobs" that work as you describe, part of a game built into a pen. It's probably done with a plastic shaft with molded tabs that push on spring strips that form contacts. You're talking about 8 switches per knob (0, 90, 180, and 270 degrees, push / pull, twist right left) for a total of 4 x 8 = 32 switches at least. The StampWorks Manual is downloadable from Parallax's website (www.parallax.com/Store/Microcontrollers/BASICStampModules/tabid/134/txtSearch/stampworks/List/1/ProductID/144/Default.aspx?SortField=ProductName%2cProductName). Experiment #24 shows how to use a 74HC195 shift register to expand the number of inputs in groups of 8.

I'd suggest using the Board of Education. You can use the little breadboard for experimentation, then you can use the breadboard to hold 0.1" pins for connecting via jumpers to your display and a separate board (breadboard or printed circuit board) that would hold the 4 - 74HC195s and other associated parts for the switches.

Link774

Thanks for the reply Mike! I found a friend who had a Board of Education that he wasn't using, so that's a start. I was looking at displays and found one that had pins for a 5x5 keypad interface. Would this be a possible route to eliminate the need for a 74HC195 since I need 16 switches? The display would do the job of converting the input to serial and passing it on to the stamp.

Could I make my own matrix keypad with a series of switches? That is essentially what the knobs are going to be. Here's a link to the display I was looking at:

http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=694170&

Thanks!
Link774