Diff: main.cpp

Revision:

0:f3eff68b603f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Thu Sep 24 12:32:02 2015 +0000
@@ -0,0 +1,46 @@
+#include "mbed.h"
+
+//Global PWM object
+PwmOut pwmRed(D7);
+
+int T = 100;    //100uS
+volatile int Tmark = 0; //0us
+volatile int delta = 1; //1us
+int n=0;
+
+//Timer
+Ticker t;
+
+//Function prototype 
+void doTwinkle();
+
+int main() {
+    
+    //Initial PWM state
+    pwmRed.period_us(T);
+    pwmRed.pulsewidth_us(Tmark);
+    
+    //Start timer
+    t.attach(doTwinkle, 0.01);
+    
+    while(1) {
+        sleep();
+        
+        //Update PWM
+        pwmRed.pulsewidth_us(Tmark);
+        
+        //printf("Tmark = %d\n", Tmark);    //Debug
+    }
+}
+
+//ISR for Timer
+void doTwinkle()
+{
+    //Update n
+    n++;
+    
+    //Calculate t 
+    float t = (float)n / (float)T;
+    float y = sin(2.0f*3.1415926f*t); //Range -1...+1
+    Tmark = (int)(0.5f*(y+1.0f)*T);   //Range 0..T
+}
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