Revision 7:499cb5f74444, committed 2020-01-24

Comitter:

eencae

Date:

Fri Jan 24 12:06:25 2020 +0000

Parent:

6:862813faf0c7

Commit message:

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Changed in this revision

diff -r 862813faf0c7 -r 499cb5f74444 main.cpp
--- a/main.cpp	Fri Jan 24 12:05:34 2020 +0000
+++ b/main.cpp	Fri Jan 24 12:06:25 2020 +0000
@@ -7,45 +7,43 @@
 Demonstrates how to use InterruptIn to generate an event-triggered interrupt
 
 (c) Craig A. Evans, University of Leeds, Jan 2016
-Updated January 2020
 
 */ 
 
 #include "mbed.h"
 
-// Create objects for button and LED
-InterruptIn buttonA(PTC7);
-DigitalOut led1(PTA2);
+// 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
 // g_ prefix makes it easier to distinguish it as global
-volatile int g_buttonA_flag = 0;
+volatile int g_sw2_flag = 0;
 
 // function prototypes
-void buttonA_isr();
+void sw2_isr();
 
 int main()
 {
-    buttonA.mode(PullUp); // turn on internal pull-up resistor
-    // pin will be 1 (3.3 V) when not pressed and 0 (0 V) when pressed
-    
-    // We therefore need to look for a falling edge on the pin to fire the interrupt
-    // when the button is pressed
-    buttonA.fall(&buttonA_isr);
- 
-    // the LED is a common anode - writing a 1 to the pin will turn the LED OFF
-    led1 = 1;
+    // 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 (g_buttonA_flag) {
-            g_buttonA_flag = 0;  // if it has, clear the flag
+        if (g_sw2_flag) {
+            g_sw2_flag = 0;  // if it has, clear the flag
 
             // send message over serial port - can observe in CoolTerm etc.
             printf("Execute task \n");
-
-            led1 = !led1; // toggle LED
+            // DO TASK HERE
         }
 
         // put the MCU to sleep until an interrupt wakes it up
@@ -54,8 +52,8 @@
     }
 }
 
-// Button A event-triggered interrupt
-void buttonA_isr()
+// SW2 event-triggered interrupt
+void sw2_isr()
 {
-    g_buttonA_flag = 1;   // set flag in ISR
+    g_sw2_flag = 1;   // set flag in ISR
 }