hi!
Im doing an exam project at school. My idea is to build a simple electronic combination lock (here) , but i want to use a rotary dial (**broken link removed**) to determan what buttons are pressed (so no buttons really), instead of actually pressing buttons. So i read on some other site how a rotary dial works, and this is how:
But my problem is: how do i count the pulses so i can find out what number is dailed? I have found some PIC solutions out there, but the problem is i have to keep it really simple (and cheap!) using IC's so i easily can explain how it works at my exam (and get a good grade
Andy
Im doing an exam project at school. My idea is to build a simple electronic combination lock (here) , but i want to use a rotary dial (**broken link removed**) to determan what buttons are pressed (so no buttons really), instead of actually pressing buttons. So i read on some other site how a rotary dial works, and this is how:
Code:
Timing Diagram. number 5 is dailed
* * * *| Dial is stationary | Dial is rotated to number |* Dail is released* | Dial stops
* * * * * * * * * * * * * * *________________________________________________
latch ______________________/* * * * * * * * * * * * * * * * * * * * * * * * \____________
* * * __________________________________________________* *_* *_* *_* *_* *_______________
pulse* * * * * * * * * * * * * * * * * * * * * * * * * *\_/ \_/ \_/ \_/ \_/
3 simple rules:
- If pulse changes from low to high, increment a counter
- If latch changes from low to high, reset the counter
- If latch changes from high to low, the number is added
* to a circular buffer and the buffer is compared to the pin codeBut my problem is: how do i count the pulses so i can find out what number is dailed? I have found some PIC solutions out there, but the problem is i have to keep it really simple (and cheap!) using IC's so i easily can explain how it works at my exam (and get a good grade
Andy