The code can hold up to six lines of text with a maximum of 100 characters each. Pressing a key on the keyboard gets you to input mode. Use the up and down arrow keys to select which line to edit. ENTER puts the system back into output mode. When in output mode, each line of text will display for 1 second (you can set this in the sketch), or if the line is longer than 16 characters, it will scroll across the display before moving onto the next line.
Send some text messages:
The uses for this contraption are many. Plug the keyboard in and enjoy putting your wittiest “wiseclacks” on it in the safety of your home, shop, or office, or use the battery option to take it into the wide world. We like to leave the keyboard accessible so that passers by can add a riposte or two to the dialogue, but if monologue is more your thing you can always take it elsewhere. Here's another idea: drill a broomstick-sized hole in the bottom of the frame and add a removable handle so you can wander the streets digitally promoting your geekified political leanings. Score keeping at sports events, birthday greetings, advertising your wares at a farmers market, beaming cryptic messages to your neighbours across the street – the possibilities are endless!
Step 1: Materials and tools
Frame wood (A): 4' of 1x4 (nominal dimensions) or similar sized board, or double that length of 3/4” x 1 5/8” stock
Eight wood screws (B): #8, 1 ¼” long
Three 8x32 dot matrix LED displays from Sure Electronics (C). $12.90 ea. http://www.sureelectronics.net/goods.php?id=1118
DC power jack to match your adapter (E). Here is a standard 2.1mm one from Sparkfun for $1.25 http://www.sparkfun.com/products/119
SPDT (on-off-on) power switch (D). Digikey part#: 450-1527-ND
PS/2 port from an old computer motherboard (F) (ask a local computer shop and they will likely give you a defunct motherboard for free).
A 21” x 4” piece of 1/8” or 1/4” Lexan or Plexiglass (G) (try your local auto glass shop). I used this to make a clear back for the frame, so that you could still see the stuff going on inside. Wood paneling or plastic would work too.
2 AA battery holder (I) http://www.sparkfun.com/products/551
4 AA battery holder in a long, flat configuration (H) http://www.sparkfun.com/products/9547
A few feet of 22 AWG stranded wire (J).
Flexible breadboard jumpers (K). $6.00 at Solarbotics: http://www.solarbotics.com/products/21035/
You can use solid 22 AWG wire for this, but purpose-built breadboard jumpers are more flexible and much easier to use – well worth the expense.
Electrical tape or heat shrink tubing (L).
Mini self-adhesive breadboard (M): $3.95 at Sparkfun: http://www.sparkfun.com/products/8802 or $4.00 at MakerShed: http://www.makershed.com/ProductDetails.asp?ProductCode=MKKN1
Ardweeny microcontroller (N), from MakerShed ($9.95) http://www.makershed.com/ProductDetails.asp?ProductCode=MKSB012 or Solarbotics ($9.99) http://www.solarbotics.com/products/kardw/
The Ardweeny is an Arduino-compatible microcontroller with a tiny footprint -- just the size of the Atmega chip itself. This (and its equally diminutive cost) make it a great choice for breadboard-based projects that need to fit into small places. Unlike the Arduino, Ardweenies requires an external USB/serial programming adapter. They're pretty cheap too though: $15 from MakerShed ( http://www.makershed.com/FTDI_Friend_v1_0_p/mkad22.htm ) or Sparkfun ( http://www.sparkfun.com/products/9716 )
5v regulator (O). 7805 series regulators are cheap and plentiful ($0.29 from MakerShed: http://www.makershed.com/ProductDetails.asp?ProductCode=JM51263) but a low dropout model like the lm2937 will give you more run time on batteries, especially if you're using lower-voltage NiMH AAs ($1.50 at Solarbotics: http://www.solarbotics.com/products/lm2937/)
0.1 μF (104) ceramic capacitor (P)
10 μF electrolytic capacitor (Q)
Six small pan head screws (R) (for holding on the back cover)
9 – 12v AC/DC adaptor (S). The best place I've found to get adaptors is a Salvation Army thrift store. They usually have a large selection for about $1 a piece. If you haven't got a thrift store handy, there's one for $5.95 at Sparkfun (http://www.sparkfun.com/products/298) or $6.50 at MakerShed (http://www.makershed.com/ProductDetails.asp?ProductCode=MKSF3)
Standard PS/2 computer keyboard (T), or USB keyboard with PS/2 adapter.
For reduced hassle and time input, a kit containing the collected materials to build this project can be purchased at the Maker Shed Store: http://www.makershed.com/PS_2_You_Parts_Kit_p/msps2u.htm
Hand saw or chop saw
Table saw (optional)
Drill and bits
Soldering iron and solder
Pliers and cutters
FTDI serial programmer (available from sparkfun for $14.95 -- http://www.sparkfun.com/products/9716)