"Added two examples for using attachInterrupt. One shows the use of a global function. While the second shows the use of a static class method as the event handler. Both work on Maple REVC

Signed-off-by: Aditya Gaddam <adityagaddam@gmail.com>"

2 files changed, 141 insertions, 0 deletions

diff --git a/examples/exti-interrupt-callback.cpp b/examples/exti-interrupt-callback.cpp
new file mode 100644
index 0000000..9f018cf
--- /dev/null
+++ b/examples/exti-interrupt-callback.cpp
@@ -0,0 +1,90 @@
+// Toggles the built-in LED when the built in button
+// on the Maple is pushed in. This uses the attachInterrupt function to
+// setup the interrupt handler for the button being pressed.
+//
+// This is similar to the exti-interrupt example, but shows the use of a class
+// method to handle interrupts.
+// 
+// More about attachInterrupt: 
+// http://leaflabs.com/docs/lang/api/attachinterrupt.html
+// 
+
+
+#include <wirish/wirish.h>
+
+class MyAwesomeClass
+{
+public:
+	// Setup the interrupt handler
+	void initialize()
+	{
+		// LED is off by default
+		this->isLEDOn = false;
+		
+		// Attach interrupt to class method handler
+		attachInterrupt(BOARD_BUTTON_PIN, buttonInterruptHandler, this, RISING);
+	}
+	
+private:
+
+	bool isLEDOn;
+
+	// Static event handler takes a void * argument that was originally 
+	// passed to the attachInterrupt call. If the argument in question is an 
+	// instance of the class (MyAwesomeClass in this case), the static function
+	// get access to that instance's data (even private data). 
+	//
+	// In other words, this setup allows the Maple to have class method 
+	// interrupt handlers (albeit with a work around).
+	//
+	// However, as you might imagine, this argument can be anything (if you 
+	// don't need instance data access).
+	//
+	static void buttonInterruptHandler(void *arg)
+	{
+		// Cast the "generic" void argument to the class instance.
+		MyAwesomeClass *instance = (MyAwesomeClass *)arg;
+		
+		// Accessing private instance data
+		instance->isLEDOn = !(instance->isLEDOn);
+		
+		// Set LED
+		digitalWrite(BOARD_LED_PIN, instance->isLEDOn);
+		
+		// Delay slightly for switch de-bouncing
+		delay(20);
+	}
+};
+
+MyAwesomeClass myClass;
+
+// Setup pin modes and the interrupt handler class
+void setup() {
+	pinMode(BOARD_BUTTON_PIN, INPUT);
+    pinMode(BOARD_LED_PIN, OUTPUT);
+    
+    // The initialize method sets up the event handler to the private method
+    // in MyAwesomeClass. There is however, nothing stopping you from setting 
+    // up event handlers which are public methods in classes.
+    myClass.initialize();
+}
+
+// Loop. Does nothing in this example.
+void loop() {
+    
+}
+
+// Force init to be called *first*, i.e. before static object allocation.
+// Otherwise, statically allocated objects that need libmaple may fail.
+__attribute__((constructor)) void premain() {
+    init();
+}
+
+int main(void) {
+    setup();
+
+    while (true) {
+        loop();
+    }
+    return 0;
+}
diff --git a/examples/exti-interrupt.cpp b/examples/exti-interrupt.cpp
new file mode 100644
index 0000000..06d6b6f
--- /dev/null
+++ b/examples/exti-interrupt.cpp
@@ -0,0 +1,51 @@
+// Toggles the built-in LED when the built in button
+// on the Maple is pushed in. This uses the attachInterrupt function to
+// setup the interrupt handler for the button being pressed.
+// 
+// More about attachInterrupt: 
+// http://leaflabs.com/docs/lang/api/attachinterrupt.html
+// 
+
+#include <wirish/wirish.h>
+
+// LED is off by default
+bool isLEDOn = false;
+
+// Interrupt handler takes in nothing and returns nothing.
+void interruptHandler()
+{
+	// Set LED
+	isLEDOn = !isLEDOn;
+	digitalWrite(BOARD_LED_PIN, isLEDOn);
+	
+	// Delay slightly for switch debouncing.
+	delay(20);
+}
+
+// Setup pin modes and the interrupt handler
+void setup() {
+	pinMode(BOARD_BUTTON_PIN, INPUT);
+    pinMode(BOARD_LED_PIN, OUTPUT);
+    
+    attachInterrupt(BOARD_BUTTON_PIN, interruptHandler, RISING);
+}
+
+// Loop. Does nothing in this example.
+void loop() {
+    
+}
+
+// Force init to be called *first*, i.e. before static object allocation.
+// Otherwise, statically allocated objects that need libmaple may fail.
+__attribute__((constructor)) void premain() {
+    init();
+}
+
+int main(void) {
+    setup();
+
+    while (true) {
+        loop();
+    }
+    return 0;
+}