   if (armingButtonState == HIGH) {
     receiveData(1);
   }
+  
+  triggerState = digitalRead(triggerPin);
+  if (triggerState == HIGH && systemArmed) {
+    systemArmed = false;
+    digitalWrite(armedPin, LOW);
+    countdown();
+  }
 }
 
 void receiveData(int numBytes) {
   if (!systemArmed) {
     systemArmed = true;
-    
+    digitalWrite(armedPin, HIGH);
     /*
     * temporary
     */

  * temporary
  */
  pinMode(armingPin, INPUT);
}

void loop() {

void sendData() {
  
}

// nonblocking countdown timer
void countdown() {
  long curr = millis();
  long delta = millis() - curr;
  while (interval - delta >= 0) {
    /*
    * temporary
    */
    lcd.setCursor(0,0);
    lcd.print((interval - delta) / 1000);
  }
}

