mbed PWM play note to a speaker

Revision:
0:32bc20854e98
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Thu Oct 20 12:41:50 2016 +0000
@@ -0,0 +1,34 @@
+// using NuMaker-PFM-NUC472 PWM0 output to a speaker
+#include "mbed.h"
+
+#define _C5   523  // C5      =  523.25Hz
+#define _D5   587  // D5      =  587.33Hz
+#define _E5   659  // E5      =  659.26Hz
+#define _F5   698  // F5      =  698.46Hz
+#define _G5   784  // G5      =  783.99Hz
+#define _A5   880  // A5      =  880.00Hz
+#define _B5   988  // B5      =  987.77Hz
+#define _C6   1046 // C6      = 1046.50Hz
+#define _D6   1175 // D6      = 1174.66Hz
+#define _E6   1319 // E6      = 1318.51Hz
+#define _F6   1397 // F6      = 1396.91Hz
+#define _G6   1568 // G6      = 1567.98Hz
+#define _A6   1760 // A6      = 1760.00Hz
+#define _B6   1976 // B6      = 1975.53Hz
+
+PwmOut pwm0(PF_9); // PWM0 pin 
+
+int main()
+{
+        int i =0;
+        int note[15] = { // array of notes
+        _C5, _D5, _E5, _F5, _G5, _A5, _B5,         
+        _C6, _D6, _E6, _F6, _G6, _A6, _B6};
+        
+        for (i=0; i<14; i++) {
+            pwm0.period_us(1000000/note[i]);       // set period per note
+            pwm0.pulsewidth_us(1000000/note[i]/2); // set duty cycle to 50%
+            Thread::wait(100);
+        }
+        pwm0.pulsewidth_us(0); // set dutycycle = 0% to stop
+}