Diff: main.cpp

Revision:

0:5737b1972549

Child:

1:09b69f38fc73

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Wed May 11 12:04:37 2011 +0000
@@ -0,0 +1,56 @@
+/*This is a program to output a sinwave in 12 bits 
+Digital to Analog converter MCP4922. Sampling frequency is 
+166,667Hz and produce an interrupt of Ticker every 6uS. 
+The Program calculates the data of the signature wave beforehand.
+*/
+#include "mbed.h"
+#include "TextLCD.h"
+#include "MCP4922.h"
+
+MCP4922 MCP(p5, p7,p8);  // MOSI, SCLK, CS
+TextLCD lcd(p24, p26, p27, p28, p29, p30);
+Ticker sampling;
+
+#define PI             3.141593
+#define MaxRes         800
+/// Global Variables
+unsigned int           OutData[MaxRes];
+unsigned int           Maxindex;
+unsigned long          Fsample;
+unsigned long          Freq;
+unsigned int           index = 0;
+
+void GenWave(void) {
+        unsigned int i;
+
+        Maxindex = (int) (Fsample / Freq);
+        if(Maxindex > MaxRes) {
+                Fsample = Freq * MaxRes;
+                     Maxindex = MaxRes;
+        }
+        for(i=0; i<Maxindex; i++) {
+                OutData[i] =  (int)(0x1FF * (1+ sin((2*PI*Freq*i)/Fsample))/2);
+        }
+}
+void timer_int(){
+        /// Output to D/A Converter
+        MCP.writeA(OutData[index]);
+        index++;
+        if(index >= Maxindex) index = 0;
+}
+
+/**** Main Function  ***/
+int main(void) {
+        MCP.frequency(20000000);
+
+        lcd.cls();
+        lcd.printf("MCP4922 Sinewave");
+
+        Fsample = 166667;
+        Freq   = 1000;
+        GenWave();
+
+        sampling.attach_us(&timer_int, 6); 
+        while(1){
+        }
+}
\ No newline at end of file