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libraries/Low-Power/Examples/standbyExternalInterruptSAMD21/standbyExternalInterruptSAMD21.ino

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+// **** INCLUDES *****
+#include "LowPower.h"
+
+// External interrupt on pin 0 (use pin 0 to 24, except pin 4 on Arduino Zero)
+const int pin = 0;
+unsigned char count = 10;
+
+void setup()
+{
+	// Wait for serial USB port to open
+	while(!SerialUSB);
+	SerialUSB.println("***** ATSAMD21 Standby Mode Example *****");
+	
+	// ***** IMPORTANT *****
+	// Delay is required to allow the USB interface to be active during
+	// sketch upload process
+	SerialUSB.println("Entering standby mode in:");
+	for (count; count > 0; count--)
+	{
+	  SerialUSB.print(count);	
+	  SerialUSB.println(" s");
+	  delay(1000);
+  }
+  // *********************
+    
+  // External interrupt on pin (example: press of an active low button)
+  // A pullup resistor is used to hold the signal high when no button press
+  attachInterrupt(pin, blink, LOW);
+}
+
+void loop() 
+{
+	SerialUSB.println("Entering standby mode.");
+	SerialUSB.println("Apply low signal to wake the processor.");
+	SerialUSB.println("Zzzz...");
+	// Detach USB interface
+	USBDevice.detach();
+  // Enter standby mode
+  LowPower.standby();  
+  // Attach USB interface
+  USBDevice.attach();
+  // Wait for serial USB port to open
+  while(!SerialUSB);
+  // Serial USB is blazing fast, you might miss the messages
+  delay(1000);
+  SerialUSB.println("Awake!");
+  SerialUSB.println("Send any character to enter standby mode again");
+  // Wait for user response
+  while(!SerialUSB.available());
+  while(SerialUSB.available() > 0)
+  {
+		SerialUSB.read();
+	}
+}
+
+void blink(void)
+{
+
+}