mjk: Binary clock is a clock representing time in binary coded decimals. This means that each value of the current time (hours, minutes, seconds) are extracted as an independent ten-based values (hours between 0-23, minutes and seconds between 0-59). Each of these values are treated as two digit values (so, for example, three minutes past five would be represented as: 05 03). To get a binary representation out of these values, each pair is chopped to single digits (0 5 0 3). Now each of these digits can be treated as a single 4-bit value and the time can be represented by using LEDs or some other kind of methods to show the state of the bits inside of these values.
Here's a small application I made for my own amusement:
# Title: Binary Clock
# Author: Matti J. Kärki
# Date: 30.8.2004
# Description: A small Tcl/Tk application showing current time in
# Binary Coded Decimal (BCD) format. This application
# requires the Img package.
package require Tk
package require Img
# Background color for the window. Note that the color
# "#0000AC" is the background color used in the images
# representing the LEDs.
set BGCOLOR {#0000AC}
# Base64 encoded image data for a non-lit LED (in BMP format).
set OFFIMGDATA {
Qk3mAQAAAAAAADYAAAAoAAAADAAAAAwAAAABABgAAAAAALABAAAAAAAAAAAA
AAAAAAAAAAAArAAArAAArAAArAAAAAAAAAAAAAAAAAAArAAArAAArAAArAAA
rAAArAAAAAAAAAAA/wAA/wAA/wAA/wAAAAAAAAAArAAArAAArAAAAAAA/wAA
/wAA/wAA/wAA/wAA/wAA/wAA/wAAAAAArAAArAAAAAAA/wAA/wAA/wAA/wAA
/wAA/wAA/wAA/wAAAAAArAAAAAAA/wAA/wAA/wAA/wAA/wAA/wAA/wAA/wAA
/wAA/wAAAAAAAAAA/wAA/wAA/wAA/wAA/wAA/wAA/wAA/wAA/wAA/wAAAAAA
AAAA/wAA/wAA/wAA/wAA/wAA/wAA/wAA/wAA/wAA/wAAAAAAAAAA/wAA/wAA
/////wAA/wAA/wAA/wAA/wAA/wAA/wAAAAAArAAAAAAA/wAA/////////wAA
/wAA/wAA/wAA/wAAAAAArAAArAAAAAAA/wAA/wAA/wAA/wAA/wAA/wAA/wAA
/wAAAAAArAAArAAArAAAAAAAAAAA/wAA/wAA/wAA/wAAAAAAAAAArAAArAAA
rAAArAAArAAArAAAAAAAAAAAAAAAAAAArAAArAAArAAArAAA}
# Base64 encoded image data for a lit LED (in BMP format).
set ONIMGDATA {
Qk3mAQAAAAAAADYAAAAoAAAADAAAAAwAAAABABgAAAAAALABAAAAAAAAAAAA
AAAAAAAAAAAArAAArAAArAAArAAAAAAAAAAAAAAAAAAArAAArAAArAAArAAA
rAAArAAAAAAAAAAAAAD/AAD/AAD/AAD/AAAAAAAArAAArAAArAAAAAAAAAD/
AAD/AAD/AAD/AAD/AAD/AAD/AAD/AAAArAAArAAAAAAAAAD/AAD/AAD/AAD/
AAD/AAD/AAD/AAD/AAAArAAAAAAAAAD/AAD/AAD/AAD/AAD/AAD/AAD/AAD/
AAD/AAD/AAAAAAAAAAD/AAD/AAD/AAD/AAD/AAD/AAD/AAD/AAD/AAD/AAAA
AAAAAAD/AAD/AAD/AAD/AAD/AAD/AAD/AAD/AAD/AAD/AAAAAAAAAAD/AAD/
////AAD/AAD/AAD/AAD/AAD/AAD/AAD/AAAArAAAAAAAAAD/////////AAD/
AAD/AAD/AAD/AAD/AAAArAAArAAAAAAAAAD/AAD/AAD/AAD/AAD/AAD/AAD/
AAD/AAAArAAArAAArAAAAAAAAAAAAAD/AAD/AAD/AAD/AAAAAAAArAAArAAA
rAAArAAArAAArAAAAAAAAAAAAAAAAAAArAAArAAArAAArAAA}
set ONIMG [image create photo -data $ONIMGDATA -format bmp]
set OFFIMG [image create photo -data $OFFIMGDATA -format bmp]
set BITS [list 1 2 4 8]
# Returns a current time in {H H M M S S} format. The format is
# suitable for representing the time in decimal or binary format.
proc getBCDtime {} {
set bcdtime {}
set tim [split [clock format [clock seconds] -format {%H %M %S}]]
foreach t $tim {
set bcdtime [concat $bcdtime [split $t {}]]
}
return $bcdtime
}
# Updates the clock display every second. This function
# scans through the return value of the getBCDtime function
# and makes a bit-vise comparsion with the elements of the
# BITS table.
proc clocktick {} {
set t [getBCDtime]
for {set x 0} {$x < 6} {incr x} {
for {set y 0} {$y < 4} {incr y} {
set y1 [expr 3 - $y]
if {[expr [lindex $t $x] & [lindex $::BITS $y]] == 0} then {
.lbl$x$y1 configure -image $::OFFIMG
} else {
.lbl$x$y1 configure -image $::ONIMG
}
}
}
after 1000 clocktick
}
# Creates a GUI. Constructs a clock display by placing a set
# of label widgets in grid. Labels are named by using the
# co-ordinates of the widget and the prefix ".lbl".
proc gui {} {
. configure -background $::BGCOLOR
for {set x 0} {$x < 6} {incr x} {
for {set y 0} {$y < 4} {incr y} {
label .lbl$x$y -image $::OFFIMG -background $::BGCOLOR
grid .lbl$x$y -column $x -row $y
}
}
}
# Start the show...
gui
clocktick