How to switch on a 12 volt SD card player with a PIR

Projects General Guidance
1

Hi, I have to do an art project in the middle of some woods so no mains electricity of course. The work is a pre recorded track that plays when entering a small hut. Its needs to go off again after say 4 or 5 mins then the track can be triggered again when the PIR is triggered etc etc.
How would I get the arduino (or anything else?) to power this player?
The player will be run from a 12 volt leisure battery.

I have several Duemilanove units.

Can anyone help with the type of sensor I would need and maybe the sketch please?
I would be able to pay someone if needed for their help.
Thank you.
Andy.

2

you need first detect PIR movement
then a delay of 5 minutes
Then swith on a line. As the Arduino is 5 Volt and the SD card is 12 Volt you need an transistor or relay to switch on the SDcard player

Both the Arduino and the SDplayer can be powered by the 12V battery - keep a small solar panel as backup?

A rude version of the sketch looks something like this:

(code not tested or compiled)

#define RELAY   4   // pin 4
#define PIR       5    

// adjust timing below to your need
#define TIMEOUT1     240000L   // 4 min = 240.000 millisec; the L is to mnake it a long integer
#define TIMEOUT2     60000L    // 1 min  

unsigned long trigger = 0;        // for timing the delays
int state = 0;                           // 0 waiting for PIR -  1 = waiting for SD;  2 = playing SD

void setup()
{
  pinMode(RELAY, OUTPUT);
  pinMode(PIR, INPUT);
  
  digitalWrite(PIR, LOW);   // disable internal pullup explicit ->  the PIR should make it HIGH
}

void loop()
{

  if (digitalRead(PIR) == HIGH  && state == 0)  // wait for high
  {
    trigger = millis();
    state = 1;
  }
  
  if (millis() - trigger > TIMEOUT1 && state == 1)
  {
    digitalWrite(RELAY, HIGH);  //start the SD
    trigger = millis();
    state = 2;
  }

  if (millis() - trigger > TIMEOUT2 && state = 2)
  {
    digitalWrite(RELAY, LOW);  // stop SDcard
    state = 0;  // reset to start modus
  }

  // there can be other code here

}

Rob

3

Thanks Rob, any ideas of how you would wire it up? Im still very much a beginner. Yes Id thought about a solar panel, do you think it would give enough charge back? Worth a try I guess. Im hoping the SD player will be low powered although it does have the amp intergral to it so that will take some power.
What else would I have to do to the Sketch if its a rude version please.
Many thanks for any assistance!!!
Andy.