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[on:]

how would I go about having 5 momentary switches being read "on" when pressed (and staying on)  and turning off the previously on switch, so there would only be one switch on at any given time?

[Reply #1 on:]

So only the last pushed button is "logically" on, even if one of the other buttons is still being held down?

[Reply #2 on:]

yes, last switch pushed. All others go off if held down. Naturally I would throw debouncing in there; software (if practical) or HW (I have a bunch of 555's laying around)

[Reply #3 on:]

Ex--

The code below tracks the state of the 5 pins and makes a note of which was pressed last.  The "button_down" variable stores the most recently pressed button pin number (or -1 if none are pressed).  In the case where button 1 is pressed and held then button 2 pressed and released, it does not record that button 1 is still active.  If this is a problem, it can be tweaked.

Is this something like what you were hoping for?

Mikal

byte pin_state[5] = {HIGH, HIGH, HIGH, HIGH, HIGH};
byte switch_pins[5] = {2, 3, 4, 5, 6};
unsigned long last_push_time[5] = {0, 0, 0, 0, 0};
int button_down = -1;

void setup()
{
  for (int i=0; i<5; ++i)
    pinMode(switch_pins, INPUT);
}

void loop()
{
  unsigned long now = millis();
  for (int i=0; i<5; ++i)
  {
    byte newstate = digitalRead(switch_pins);
    if (newstate != pin_state) // did the pin change state?
    {
      if (newstate == HIGH && now - last_push_time > 200) // debouncing
      {
        pin_state = HIGH;
        if (button_down == switch_pins)
          button_down = -1;
      }
      
      else if (newstate == LOW)
      {
        pin_state = LOW;
        button_down = switch_pins;
        last_push_time = now;
      }
    }
  }
  
  /* At this point the variable "button_down" contains the pin number
    for the most recently pressed button, or -1 if no buttons are down.
    This assumes that a button press causes the pin state to drop "LOW".
 */
}

[Reply #4 on:]

Thank you, thats what I was hoping to do,. I was afraid, as a newb that I wouldnt be able to debounce and detect without more nested loops. You have also provided me an extremely useful tutorial on the millis() call, thanks.