Hey guys I was wondering if any of you could help me.
I'm building a electronic keypad lock circuit and im trying to do it without a microcontroller. I have the 12 button keypad going to a 16-4 line encoder. Then to go oldschool I wanted to have a shift register memory bank. Specifically a 74195 4 in 4 out pipo. From there I have it going to a few comparators that compare the bits to dip switches with the desired code. If the 4 button presses match the 4 switch packs then the output on the 4 comparators is a 1. They get ANDed together. then to a bjt switching circuit to the lock. The code is 4 digits. My problem lies in the memory. How do I cascade the registers so It brings the bits in from the encoder and holds the correct bits to send to the comparators? Any suggestions would be greatly apprieciated!!!
I'm building a electronic keypad lock circuit and im trying to do it without a microcontroller. I have the 12 button keypad going to a 16-4 line encoder. Then to go oldschool I wanted to have a shift register memory bank. Specifically a 74195 4 in 4 out pipo. From there I have it going to a few comparators that compare the bits to dip switches with the desired code. If the 4 button presses match the 4 switch packs then the output on the 4 comparators is a 1. They get ANDed together. then to a bjt switching circuit to the lock. The code is 4 digits. My problem lies in the memory. How do I cascade the registers so It brings the bits in from the encoder and holds the correct bits to send to the comparators? Any suggestions would be greatly apprieciated!!!
