more analog inputs

Forum 2005-2010 (read only) General Frequently-Asked Questions
11

Here's a cheap and nasty technique that addresses 8 LDRs over 3 digital outs and an analogue in. You should be able to adapt it:

And here's some poor quality code to run it:

void select_sensor(int sensor) {
  digitalWrite(2,LOW);
  digitalWrite(3,LOW);
  digitalWrite(4,LOW);
  if (sensor & 1) {
    digitalWrite(2,HIGH);
  } 
  if (sensor & 2) {
    digitalWrite(3,HIGH);
  } 
  if (sensor & 4) {
    digitalWrite(4,HIGH);
  } 
}

You'll need to set pins 2, 3 and 4 to outputs in setup().

Pass a sensor number (0-7) to select_sensor() and perform an analogue read on analogue pin 0 to get a value back from the selected sensor.