Diff: main.cpp

Revision:

0:d76a3b12c090

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Mon Aug 17 00:09:19 2015 +0000
@@ -0,0 +1,81 @@
+#include "mbed.h"
+ 
+//Number of dutycycle steps for output wave
+#define SAW_STEPS          33
+
+//Frequency of output sine in Hz
+#define SAW_OUT_FREQ       1
+ 
+//Frequency of Pulse Width Modulated signal in Hz
+#define PWM_FREQ            6600
+
+float saw_duty[SAW_STEPS];
+ 
+//PWM pin
+PwmOut mypwm(D10);
+ 
+//Heartbeat LED
+DigitalOut myled(LED1);
+ 
+//Ticker to update the PWM dutycycle
+Ticker pwm_ticker;
+ 
+//Ticker calls this fucntion to update the PWM dutycycle
+void pwm_duty_updater() {
+  static int idx = 0;
+  mypwm.write(saw_duty[idx]);   // Set the dutycycle % to next value in array
+  idx++;                         // Increment the idx
+  if (idx == SAW_STEPS) idx=0;  // Reset the idx when the end has been reached  
+}
+  
+int main() {
+    float saw[] =   {0,
+                     0.03125,
+                     0.0625,
+                     0.09375,
+                     0.125,
+                     0.15625,
+                     0.1875,
+                     0.21875,
+                     0.25,
+                     0.28125,
+                     0.3125,
+                     0.34375,
+                     0.375,
+                     0.40625,
+                     0.4375,
+                     0.46875,
+                     0.5,
+                     0.53125,
+                     0.5625,
+                     0.59375,
+                     0.625,
+                     0.65625,
+                     0.6875,
+                     0.71875,
+                     0.75,
+                     0.78125,
+                     0.8125,
+                     0.84375,
+                     0.875,
+                     0.90625,
+                     0.9375,
+                     0.96875,
+                     1};
+                      
+    for (int i = 0; i < SAW_STEPS; i++)    {
+        saw_duty[i] = saw[i];
+    }
+                      
+    // Set PWM frequency
+    mypwm.period( 1.0f / (float) PWM_FREQ);
+ 
+    // Init the Ticker to call the dutycyle updater at the required interval
+    // The update should be at (SINE_STEPS * SINE_OUT_FREQ) 
+    pwm_ticker.attach(&pwm_duty_updater, 1.0f / (float)(SAW_STEPS * SAW_OUT_FREQ));
+ 
+    while(1){ //infinite loop
+    myled = !myled; 
+    wait(0.5);  
+  }
+}
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