Electronic – Digital project


i need some advice how to prepare digital electronic circuit.

I have 64 signal lines, every line have a NO tact switch with latch . I need desiplay how much "1 or ON" signal i have and display this value on two 7segment displays.

i can't use microcontroller/microprocessor/fpga or equivalent device.
only mux/demux/counter/decoder and other "simple digital stuff"

every tip will be helpful


My idea is: connect 65 resistors in series 64x100Ohm + 1×6.4kOhm(Like a shunt resitor). Every single resistor from 64 will be connected parrarel with button if i click the button then i will have a bigger voltage drop on 6.4kOhm resistor. The voltage drop on 6.4k resistor connect to flash adc and then move out signal from priority encoder to 2x7seg displays.

Best Answer

If you want to take many inputs that's not the proper way. As you have 64 input lines so you need a 64-bit ring counter and a clock source. As a 64-bit ring counter isn't available, you need to couple some 8-bit shift registers. Each output would be connected to a switch through a diode. And the other terminals of all switches need to be short-circuited and pulled down through one 10K resistor. The short-circuited bus is the output bus and the status of this bus is needed to be checked at the falling edge of each clock pulse. This is done through the AND product of the output bus and inverted clock signal. As you need to count the 1, so just connect the output of AND gate to a counter. The simulation result with diagrams is here.

In addition, the counter has to be refreshed after each 64 clock pulse elapsed. I can't help you with how to display the counter value in 7 segment display right now. But you will find enough resources about that on the internet.