Diff: main.cpp

Revision:

14:b4fed570abaf

Parent:

13:7ab71c7c311b

Child:

17:d6a3b29cab31

diff -r 7ab71c7c311b -r b4fed570abaf main.cpp
--- a/main.cpp	Sat May 09 13:56:14 2015 +0000
+++ b/main.cpp	Sat May 09 14:39:48 2015 +0000
@@ -48,8 +48,34 @@
 
 StateManager* fsm;
 
+AnalogIn randomPin(p18); // Unconnected pin => noise, used for generating a random seed.
+AnalogIn randomPin2(p19); // Unconnected pin
+
+/// Function for generating a random seed by using a unconnected analog input pin
+// Problem: Not trully random as pin is fairly stable. It is unfortunately connected to the ground layer (often returning 0). Would be better to connect it to a "loose wire"/bad connection
+unsigned int getRandSeed()
+{
+    unsigned int randNum = 0;
+    unsigned int lsb; // least significant bit
+    
+    for (unsigned int i = 0; i < 16; ++i)
+    {
+        lsb = 1 & (randomPin.read_u16()); // Read least significant bit in randomInput - value depends on noise
+        randNum |= (lsb << i);              // Set bit nr.i to lsb in randomInput
+        
+        lsb = 1 & (randomPin2.read_u16());
+        randNum |= (lsb << (16+i));
+    }
+    
+    return randNum;
+}
+
+Serial term(USBTX, USBRX); // TO DELETE - DEBUGGING ONLY
+
 int main()
-{
+{    
+    srand(getRandSeed());
+    
     init();
     
     Timer timer;