Debug:

LED ON = Digital pins pulled high (internal pullup) = Motion Sensed (Or Faulty PIR / Wiring)

/* PIR Motion Sensor to MIDI Trigger w timer
 25/3/2017 Dargstronix

 Hardware: 
 1x PIR Sensor (4 pins to sensor = 12v, GND, 2x alarm pins) * Could add more sensors for increased responsiveness to movement)
 1x 12v 500mA PSU for PIR 
 PIR Alarm Pins to Teensy GND / Pin 0 
 1x Teensy v3.5 (5v version) - Set USB Type to MIDI + Serial * Powered by USB (mac pro)
 
 Compiled under Arduino v 1.6.13 https://www.arduino.cc/en/Main/OldSoftwareReleases#previous
 Teensyduino 1.35 https://www.pjrc.com/teensy/td_download.html
 VDMX Detect MIDI on Video Layer (Default CC 11)
 
*/

int pirPin = 0; // Pin for PIR (Normally Closed)
int ledPin = 13; // Built in LED (default pin 13) NO Hardware PWM on Pin 13.
long counter = 0; // counter
long video = 0; // value to store state of if video should play or not.
int ledState = LOW; // ledState used to set the LED
long previousMillis = 0; // will store last time LED was updated
unsigned long currentMillis = millis();


/* User Config */

long duration = 5000; // Time to wait before turning up idle video loop (in mS) 5000 = 5 seconds, 60000 = 60seconds
int fadetime = 20; // fade up/down time in mS ( x 128 ) = 2.5 seconds
int midich = 0; // MIDI Channel: 0 is default
int midicc = 11; // MIDI Control Channel: 11 (MIDI CC Volume) is default 


void setup() 
{
 pinMode(pirPin, INPUT_PULLUP); // internal pullup to HIGH
 pinMode(ledPin, OUTPUT);
 Serial.begin(9600); // debug
}


void loop() 
{
 currentMillis = millis();
 int pirState = digitalRead(pirPin);
 Serial.print(" pirState: "); //debug
 Serial.print(pirState); //debug

if (pirState == HIGH) // If PIR triggered
 { 
 digitalWrite(ledPin, HIGH);

 if (video==1)// If video was playing, then make it not play
 { 
 Serial.println(" *** WAS PLAYING NOW VIDEO OFF 0 "); //debug
 video=0;
 fadedown();
 //usbMIDI.sendControlChange(11, 0, 0); // volume =11, value 0,ch0
 }
 
 Serial.print(" TRIGGERED - Artwork Active, counter reset, video off: "); //debug
 counter = currentMillis; // reset counter
 }
 

if (pirState == LOW) // If PIR isn't triggered
 {
 Serial.print(" No Trig "); //debug
 blink(500);
 }
 


if(currentMillis - counter > duration) 
 {
 if (video==0) // If video wasn't playing
 { 
 video=1;
 fadeup();
 Serial.println(" *** WASN't PLAYING NOW VIDEO ON 127 "); //debug
 }
 
 Serial.print(" * DURATION Exceeded - ARTWORK INACTIVE - turn up video * "); //debug
 blink(50);
 }

 Serial.print(" Millis - counter: "); //debug
 Serial.println(currentMillis - counter); //debug 
 

 while (usbMIDI.read()) { // ignore incoming messages
 // MIDI Controllers should discard incoming MIDI messages.
 // http://forum.pjrc.com/threads/24179-Teensy-3-Ableton-Analog-CC-causes-midi-crash 
 }
} //end main loop 


void fadeup()
{
 for (int x = 0; x < 128; x++)   {  usbMIDI.sendControlChange(midicc, x, midich); // volume =11, value x, ch0  delay(fadetime);    int val = x;  val = map(val, 0, 128, 0, 255);  analogWrite(ledPin, val);  Serial.print(" val= "); //debug  Serial.println(val); //debug   Serial.print(" x= "); //debug  Serial.println(x); //debug   } } void fadedown() {  for (int x = 127; x >- 1; x--) 
 {
 usbMIDI.sendControlChange(midicc, x, midich); // volume =11, value x, ch0
 delay(fadetime);
 
 int val = x;
 val = map(val, 0, 128, 0, 255);
 analogWrite(ledPin, val);

 Serial.print(" val= "); //debug
 Serial.println(val); //debug 
 Serial.print(" x= "); //debug
 Serial.println(x); //debug 
 }
}

void blink(int blinky)
{
 if(currentMillis - previousMillis > blinky) 
 {
 previousMillis = currentMillis; // save the last time you blinked the LED 
 if (ledState == LOW) // if the LED is off turn it on and vice-versa: 
 ledState = HIGH;
 else
 ledState = LOW;
 digitalWrite(ledPin, ledState); // set the LED with the ledState of the variable: 
 }
}