Normally the Analog Input A1 is pulled high by resistor R4. If any of the switches S1, S2, or S3 is closed, the resistance changes in a predetermined way. Circuit-wise, each of the resistors R1, R2, and R3 would add to the total resistance using the familiar circuit formula 1/R = 1/R1+1/R2+1/R3. All we have to do is measure the analog values read by the Trinket and add them to our code. This method also works equally well for normally open or normally closed switches. | Normally the Analog Input A1 is pulled high by resistor R4. If any of the switches S1, S2, or S3 is closed, the resistance changes in a predetermined way. Circuit-wise, each of the resistors R1, R2, and R3 would add to the total resistance using the familiar circuit formula 1/R = 1/R1+1/R2+1/R3. All we have to do is measure the analog values read by the Trinket and add them to our code. This method also works equally well for normally open or normally closed switches. |