Diff: main.cpp

Revision:

1:f650db6c33e4

Parent:

0:2f4ee2a22324

Child:

2:8211254a87fd

--- a/main.cpp	Fri Feb 17 11:13:02 2017 +0000
+++ b/main.cpp	Wed Feb 22 14:06:34 2017 +0000
@@ -1,11 +1,3 @@
-/* ELEC1620 Application Board Example
-
-Buttons
-
-(c) Dr Craig A. Evans, University of Leeds, Feb 2017
-
-*/
-
 #include "mbed.h"
 
 DigitalIn button_A(p29);
@@ -13,32 +5,39 @@
 DigitalIn button_C(p27);
 DigitalIn button_D(p26);
 
-int main() {
-    
+void init_buttons();
+
+int main()
+{
+    init_buttons();  // turn off internal pull-up/pull-down resistors
+
     while(1) {
-        
-        // read each of the buttons and store in variable
-        int button_A_value = button_A.read();
-        // int button_A_value = button_A;  // this is equivalent
-        int button_B_value = button_B.read();
-        int button_C_value = button_C.read();
-        int button_D_value = button_D.read();
-        
-        // check if pressed (value will be 1 i.e. true) and print message
-        if (button_A_value) {
-            printf("Button A is pressed\n");    
+
+        // check each button in turn and print message
+        if ( button_A.read() == 1) {
+            printf("Button A pressed\n");
+        }
+        if ( button_B.read() == 1) {
+            printf("Button B pressed\n");
         }
-        if (button_B_value) {
-            printf("Button B is pressed\n");    
-        }
-        if (button_C_value) {
-            printf("Button C is pressed\n");    
+        if ( button_C.read() == 1) {
+            printf("Button C pressed\n");
         }
-        if (button_D_value) {
-            printf("Button D is pressed\n");    
+        if ( button_D.read() == 1) {
+            printf("Button D pressed\n");
         }
-        
-        wait(0.5);  // small delay - won't be able to read button during delay
-        
+
+        wait(0.1);  // small delay
+
     }
 }
+
+void init_buttons()
+{
+    // PCB has external pull-down resistors so turn the internal ones off
+    // (default for DigitalIn)
+    button_A.mode(PullNone);
+    button_B.mode(PullNone);
+    button_C.mode(PullNone);
+    button_D.mode(PullNone);
+}