microbit: Added validation check on MicroBit::init()

Added simple validation check to protect against accidental re-initialisation.

inc/MicroBit.h

@@ -41,10 +41,7 @@
 #include "MicroBitStorage.h"
 
 // MicroBit::flags values
-#define MICROBIT_FLAG_SCHEDULER_RUNNING         0x00000001
-#define MICROBIT_FLAG_ACCELEROMETER_RUNNING     0x00000002
-#define MICROBIT_FLAG_DISPLAY_RUNNING           0x00000004
-#define MICROBIT_FLAG_COMPASS_RUNNING           0x00000008
+#define MICROBIT_INITIALIZED                    0x01
 
 // MicroBit naming constants
 #define MICROBIT_NAME_LENGTH                    5
@@ -70,6 +67,7 @@ class MicroBit
     void                    compassCalibrator(MicroBitEvent e);
     void                    onListenerRegisteredEvent(MicroBitEvent evt);
     uint32_t                randomValue;
+    uint8_t                 status;
 
     public:
 

source/MicroBit.cpp

@@ -120,7 +120,10 @@ MicroBit::MicroBit() :
     radio(),
     ble(NULL)
 {
-	// Bring up soft reset functionality as soon as possible.
+    // Clear our status
+    status = 0;
+
+    // Bring up soft reset functionality as soon as possible.
     resetButton.mode(PullUp);
     resetButton.fall(this, &MicroBit::reset);
 }
@@ -138,6 +141,9 @@ MicroBit::MicroBit() :
   */
 void MicroBit::init()
 {
+    if (status & MICROBIT_INITIALIZED)
+        return;
+
 #if CONFIG_ENABLED(MICROBIT_HEAP_ALLOCATOR)
     // Bring up a nested heap allocator.
     microbit_create_nested_heap(MICROBIT_NESTED_HEAP_SIZE);
@@ -153,6 +159,8 @@ void MicroBit::init()
     messageBus.listen(MICROBIT_ID_COMPASS, MICROBIT_COMPASS_EVT_CALIBRATE, this, &MicroBit::compassCalibrator, MESSAGE_BUS_LISTENER_IMMEDIATE);
     messageBus.listen(MICROBIT_ID_MESSAGE_BUS_LISTENER, MICROBIT_EVT_ANY, this, &MicroBit::onListenerRegisteredEvent);
 
+    status |= MICROBIT_INITIALIZED;
+
 #if CONFIG_ENABLED(MICROBIT_BLE_PAIRING_MODE)
     // Test if we need to enter BLE pairing mode...
     int i=0;