How to get input from multiple tact switches with a single input pin:
A technique of interfacing multiple tact switches using a single ADC input pin was demonstrated using the PIC12F683 microcontroller. A digital input from four tact switches were individually read through the AN0 ADC channel and displayed it back on an LED. While this technique saves input pins and reduces the size, one downside of the design is detecting combination of switches. The calculations of R’ resistors become more complex in such a case. The resistor values must be chosen very carefully so that the voltage resulting from a switch combination is unique.
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