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[on:]

I would like to pick a random pin, but with the pins named.  Does anybody know how to do this?

Code:

int ThisPin = 2;
int ThatPin = 3;
int AnotherPin = 4;
int FinalPin = 5;

I know you can get random numbers.  But I would like to get random pin names.

This is how I would like to use them:

Code:

PinMode(RandomPin,OUTPUT);
delay(20)
PinMode(RandomPin,INPUT);

More information is located here: http://arduino.cc/forum/index.php/topic,123841.msg930983.html
Last reply is where I have to use PinMode for the triggering.

Thanks,
Link

[Reply #1 on:]

Don't use variable names; stick your pin numbers in an array and use your random number as an index into the array.

[Reply #2 on:]

I didn't really want to do it that way as I am going to use those same pins on other triggers, but they will not be random...

Is this the only way though?

[Reply #3 on:]

If you use an array, you can still use the pins in areas where they are not random. The array doesn't change, hence the const keyword. Instead you pick a random element from the array.

Code:

const byte pins[] = {2,3,4,5};

void setup(){
  ...
}

void loop(){
  ...
  byte randomNumber = ... ;
  pinMode(pins[randomNumber],OUTPUT); //do something with a random pin
  delay(20)
  pinMode(pins[randomNumber],INPUT);
  ...

  ...
  digitalWrite(pins[0],HIGH); //Just an example. Element 0 is always element 0, so there is no random factor here...
}

[Reply #4 on:]

Aha...  Thanks Tom and Peter.

[Reply #5 on:]

How about

Code:

RandomPin = random(2, 14);  // assuming you don't want to step on serial comm
PinMode(RandomPin,OUTPUT);
delay(20)
RandomPin = random(2, 14);  // assuming you don't want to step on serial comm
PinMode(RandomPin,INPUT);

Lefty

[Reply #6 on:]

How about

Code:

RandomPin = random(2, 14);  // assuming you don't want to step on serial comm
PinMode(RandomPin,OUTPUT);
delay(20)
RandomPin = random(2, 14);  // assuming you don't want to step on serial comm
PinMode(RandomPin,INPUT);

Lefty

That was the way I was going to do it, but really wanted to keep the names of the pins so I would know what the trigger is.  This sketch is for a robot that will talk back to you.

[Reply #7 on:]

I didn't really want to do it that way as I am going to use those same pins on other triggers, but they will not be random...

Is this the only way though?

If you want to use named access to those pins too, you can either hold the pin numbers in ordinary named variables too, or defined an enumerated type that assigned named values to the array indices. So instead of putting thisPin and thatPin you'd use pins[ThisOne] or pins[ThatOne].

[Reply #8 on:]

Code:

enum pins_t  {ThisPin, ThatPin, AnotherPin, FinalPin};
int pins[] = {  2,       3,       4,          5};

int randpin = pins[random(4)];

pinMode(randpin, OUTPUT);
digitalWrite(pins[ThisPin], HIGH);
digitalWrite(pins[FinalPin], LOW);

[Reply #9 on:]

hmm..  I may not be able to randomize this as I want to.

The way the MP3 Trigger works in "real life,"  I have to use pinMode(ThisPin,OUTPUT); to turn the pin to ground to trigger that pin on the MP3 Trigger.  Since the MP3 Trigger will not simply rely on digitalWrite(ThisPin,LOW);/digitalWrite(ThisPin,HIGH); since it will not trigger another pin if one pin is HIGH (it supposed to but doesn't).  

So I have to use pinMode(ThisPin,OUPUT); to trigger and pinMode(ThisPin,INPUT); so I can trigger other pins on the MP3 Trigger.

So I don't think

Code:

enum pins_t  {ThisPin, ThatPin, AnotherPin, FinalPin};
int pins[] = {  2,       3,       4,          5};

int randpin = pins[random(4)];

pinMode(randpin, OUTPUT);
digitalWrite(pins[ThisPin], HIGH);
digitalWrite(pins[FinalPin], LOW);

will work if that randompin gets set to OUTPUT then that same pin (after the delay) needs to get set back to INPUT so it will not loop the sound from the MP3 Trigger.

[Reply #10 on:]

So I don't think

...

will work if that randompin gets set to OUTPUT then that same pin (after the delay) needs to get set back to INPUT so it will not loop the sound from the MP3 Trigger.

So set it back to an input afterwards, if that's what it needs.

[Reply #11 on:]

If I use "RandPin" to set it back to INPUT, how is it going to know what the first RandPin was?

[Reply #12 on:]

You just have to set it up so randpin doesn't change between becoming an output and an input.

Code:

int randpin = pins[random(4)];

pinMode(randpin, OUTPUT);
delay(20);
PinMode(randpin,INPUT);

[Reply #13 on:]

Ok, so that is what that does!  Thanks Tom.