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int currentLed = 0; void setup() { Serial.begin(19200); pinMode(12, OUTPUT); pinMode(13, OUTPUT); pinMode(14, OUTPUT); pinMode(15, OUTPUT); pinMode(A1, INPUT); pinMode(A2, INPUT); currentLed = 0; } void tristate(int pin) { pinMode(pin,OUTPUT); digitalWrite(pin,LOW); pinMode(pin,INPUT); } void power(int pin) { pinMode(pin,OUTPUT); digitalWrite(pin,HIGH); } void ground(int pin) { pinMode(pin,OUTPUT); digitalWrite(pin,LOW); } void enableLed(int led) { int row = led/2; int col = led%2; if (row==0) { power(12); ground(13); } else { ground(12); power(13); } if (col==0) { ground(14); tristate(15); } else { tristate(14); ground(15); } } int sense(int led) { int row = led/2; int value = analogRead(row == 0 ? A1 : A2);
return value < 500; } void loop() { enableLed(currentLed); delay(20); if (sense(currentLed)) { Serial.print(currentLed); Serial.println(" proximity!"); } currentLed = (currentLed+1)%4; delay(20); }
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