We recently featured some of the new hard drive clocks along with some links to some other designs. Turns out we missed one. AP Digital Light created a Hard Drive Clock which is truly a work of art. It uses a PIC18F2320 Microcontroller and a real time clock module from Spark Fun to keep things in sync. The result of his toner transfer method of board etching is about the best I have ever seen. I used to use that method before and never had results as good as he gets. You can see his demonstration video of the PCB making toner transfer method here, it looks like exactly the same method I used except the results are way better.
"Brain is implemented on PIC18F2320 running at 40MHz.
Firmware is written in "C".
Upon power-up mcirocontroller reads current time and date from RTC and then refreshes data every hour.
Two timers of microcontroller synchronize work of whole device.
Timer0 is dedicated to measure time of full disk revolution. This value is used to calculate precise moment for LEDs to turn ON/OFF. Because of that, clock will display correct result regardless of disk RPM.
External interrupt function resets Timer0 upon signal from index sensor.
Timer1 is connected to external 32768 Hz crystal and configured as real time clock with period 0.25sec. It’s used to scan keyboard, refresh LCD, and recalculate position of clock hands.
RGB LEDs are switching in main program loop.
Keyboard contains two illuminated buttons. It’s used to set correct time/data and select clock mode.
Controller is connected with external world via 8 connectors so unit can be taken apart and reassembled within seconds."
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