Wednesday, October 15, 2008
The above schematic is 8x8 Led Dot Matrix clock using PIC16F627A (or PIC16F628 which is more expensive but larger memory) and a shift register 74HC595. The PIC is running with 4MHz internal oscillator so pin 15 (RA6) and 16 (RA7) are free. Therefore, the PIC16F627a can drive the 8x8 Led Drive matrix with these 2 free pins (RA6, RA7) and RB0-5, . The Timer1 (TMR1) external clock is generated by the watch crystal 32.768KHz + load capacitors 15pF and fed to RB6 and RB7. The pins are used up!. Method of setting time is similar to the 5x7 Led Dot Matrix Clock.
I have intention to make this with SMD components so the 8x8 Dot Matrix will be the biggest component. The whole clock will be just 20x20mm which is small enough to be a small pocket watch or even a wristwatch. The only problem is the power supply.