Diff: main.cpp

Revision:

0:c616f46e44a5

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Thu Sep 24 12:32:26 2015 +0000
@@ -0,0 +1,58 @@
+#include "mbed.h"
+
+#define Fs 1000
+#define T (1.0/Fs)
+#define PI 3.1415926541
+
+PwmOut mypwm(PWM_OUT);
+
+//This GPIO is used for Chip Select
+DigitalOut DAC_CS(D10);
+
+//SPI Object
+SPI spi(D11, D12, D13);
+
+//Ticker for setting the output sampling rate
+Ticker t;
+
+//Discrete time
+unsigned int n=0;
+
+//Frequency f
+double f = 10.0;
+
+//Prototype for the ticker ISR
+void writeSample();
+
+int main() {
+
+    //Set speed of the SPI interface
+    spi.frequency(20000);
+    
+    //16 bit words, mode 0 clock
+    spi.format(16,0);
+    
+    //Write at Fs Hz    
+    t.attach(writeSample, T);
+    
+    while(1) {
+        sleep();
+    }
+}
+
+//ISR for ticker
+void writeSample()
+{
+    //Enable the selected slave device
+    DAC_CS = 0;
+    
+    //Write a header (top 4 bits) and value (bottom 12 bits) 
+    double y = cos(2.0*PI*n*f*T);
+    unsigned int val = (unsigned int)(2048.0 * (y + 1.0));
+    spi.write(0x7000 | val);
+    
+    //Disable the selected slave device (and update the output)
+    DAC_CS = 1;
+    
+    n++;
+}
\ No newline at end of file