Diff: main.cpp

Revision:

1:0b38b848a5f0

Parent:

0:025387782f3e

Child:

2:83f7d8e01b11

--- a/main.cpp	Wed Mar 02 18:01:16 2016 +0000
+++ b/main.cpp	Thu Sep 20 09:17:38 2018 +0000
@@ -1,19 +1,35 @@
 #include "mbed.h"
-/* 
- * All the LEDs on the micro:bit are part of the LED Matrix,
- * In order to get simple blinking behaviour, we set column 0
- * to be permanently at ground. If you want to use the LEDs as
- * a screen, there is a display driver in the micro:bit 'DAL',
- */
-DigitalOut col0(P0_4, 0);
+
+// Button A is on P0 bit 17 
+// Pin labelled "0" on edge connector is in fact connected to P0_3 
+volatile uint32_t * P0OUT = (uint32_t *)0x50000504;
+volatile uint32_t * P0DIR = (uint32_t *)0x50000514;
+volatile uint32_t * P0IN  = (uint32_t *)0x50000510;
+volatile uint32_t * P0CONF  = (uint32_t *)(0x50000700);
 
-DigitalOut myled(P0_13);
-
+void dly(volatile uint32_t len)
+{
+    // "volatile" modifier is necessary here 
+    // to prevent the compiler from optimizing 
+    // this software delay to nothing
+    while(len--);
+}
+int ButtonAPressed()
+{
+    // Button A pulls down so bit is zero when pressed.
+    if ((*P0IN & (1 << 17))==0)    
+        return 1;
+    else
+        return 0;
+}
 int main() {
-    while(1) {
-        myled = 1;
-        wait(0.2);
-        myled = 0;
-        wait(0.2);
+    
+    *P0DIR = (1 << 3);    
+    P0CONF[17] = 0;  // On power up, input buffer is not connected so must do this
+    while(1) {                 
+        if (ButtonAPressed()) 
+            *P0OUT = (1 << 3);       
+        else
+            *P0OUT = 0;                      
     }
 }