Diff: main.cpp

Revision:

0:185ac7c21810

Child:

1:58d6707580cb

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Tue Jan 05 16:32:28 2016 +0000
@@ -0,0 +1,55 @@
+/* 
+
+2645_InterruptIn
+
+Example code from ELEC2645 Week 15 Lab
+
+(c) Craig A. Evans, University of Leeds, Jan 2016
+
+*/ 
+
+#include "mbed.h"
+
+// Create objects for SW2 (right switch) and red LED
+InterruptIn sw2(SW2);
+DigitalOut red_led(LED_RED);
+
+// flag - must be volatile as changes within ISR
+volatile int sw2_flag = 0;
+
+// function prototypes
+void sw2_isr();
+
+int main()
+{
+    // SW2 has a pull-up resistor, so the pin will be at 3.3 V by default
+    // and fall to 0 V when pressed. We therefore need to look for a falling edge
+    // on the pin to fire the interrupt
+    sw2.fall(&sw2_isr);
+    // since SW2 has an external pull-up, we should disable to internal pull-down
+    // resistor that is enabled by default using InterruptIn
+    sw2.mode(PullNone);
+    // the on-board RGB LED is a common anode - writing a 1 to the pin will turn the LED OFF
+    red_led = 1;
+
+    while (1) {
+
+        // check if flag i.e. interrupt has occured
+        if (sw2_flag) {
+            sw2_flag = 0;  // if it has, clear the flag
+
+            // DO TASK HERE
+
+        }
+
+        // put the MCU to sleep until an interrupt wakes it up
+        sleep();
+
+    }
+}
+
+// SW2 event-triggered interrupt
+void sw2_isr()
+{
+    sw2_flag = 1;   // set flag in ISR
+}