Dear Forum Members;
For a commerical project we are planning to construct a keypad that has 3 leds(for output) and 12 buttons (for input). The keypad will 15-20 meter far away from the host mcu(89C52). Due to the costs we are planning to communicate via 2 wires(clock and data) and 2 wire for power supply. And use discrete logic components (shift registers and flip flops) rather than a mcu or cpld. Now my question is:Is it meaningful to construct such a keypad with discrete logic? If it is then what steps should i follow? Any tips, any ideas, any links or example application notes would be welcome.
Regards.
Ertan