- a slashdot tag line.
The 01/\/atch is a binary wrist watch with an LED display. Additional features are accessible through a scrolling menu system on its 3x4 LED matrix. Current features include: voltage meter, binary counter, club mode and time display. The watch is fully programmable. Future firmware upgrades will include: stopwatch/timer, alarm, bicycle speedometer/odometer, data logging, and an advanced configuration menu.
See it in action: http://www.youtube.com/watch?v=l_tApl3JmmM
All the project files are in the .zip archive on this page. Schematic and PCB in Cadsoft Eagle format. Firmware in mikroBasic. The text of this instructable is included as .odt (OO.org/open text) and .pdf files. The top-layer PCB art (mirrored) is included as a .PDF ready for toner transfer or foto process. It is copied several times on a single sheet because I have to double-up on transparencies.
The 01/\/atch was inspired by the Mini Dotclock, and a subsequent conversation in the comments area:
This is also a half step towards a surface mount nixie watch I am working on. The 01/\/atch project is an introduction to surface mount components and time keeping logic without the added complexity of a nixie tube power supply. (http://www.instructables.com/ex/i/2C2A7DA625911029BC6B001143E7E506/?ALLSTEPS )
A little googling turned up this binary watch at thinkgeek: http://www.thinkgeek.com/gadgets/watches/6a17/
The 01/\/atch is based on a PIC16F913/6. This PIC was originally chosen because it had a hardware LCD driver. I thought that I could turn the LCD driver into a LED multiplexer with a few transistors. This turned out not to be the case. Its still a good choice because it has tons of programming space and very few limited I/O pins. The F913 is about $2.00 at Mouser.
PIC16F916 Details (same as 913, with more program space):
PIC16F913/6 Datasheet (PDF format):
The 3d images used in this instructable were made from the Eagle Board files with Eagle3D and POV ray:
Step 1: Display
The LED multiplex is straightforward. Rows (4) connect to pins of the PIC through current limiting resistors. Only one current limiting resistor is used for each row because only one LED per row is ever lit. The LEDs are run at 20ma, using 56 ohm resistors (56ohm @ 3 volts=20ma). The LEDs could be run higher because they are multiplexed, the datasheet listed something around 40ma. I find them to be too bright at only 20ma-multiplexed.
Columns (3) are connected to ground by NPN transistors. The transistors are switched by PIC pins through 1Kohm resistors. The multiplex functions by grounding a column of LEDs through the transistor while lighting the correct LED rows for that column. This is repeated for each column in short succession, making the matrix appear to be continually lit. PIC Timer0 is drives the multiplex. It counts to 256 then changes row values and the grounded column.
NPN Transistor, NPN/ 32V/ 100mA, (Mouser #512-BCW60D $0.05).