Diff: sintone.cpp

Revision:

0:325b79275f25

Child:

1:516ea1ca7abb

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sintone.cpp	Thu Apr 05 04:42:52 2018 +0000
@@ -0,0 +1,55 @@
+#include <mbed.h>
+#define samplerate 16000
+#define MAXFREQS 10
+
+Serial pc(USBTX, USBRX);
+Ticker tick1;
+PwmOut pwm1(p21);
+AnalogOut da1(p18);
+
+const int scalefreqs[12*2]={440, 466,494,523,554,587,622,659,698,740,784,830,
+        880,932,987,1046,1109,1175,1245,1319,1397,1480,1568,1661};
+signed char bytesintab[samplerate];
+int  freqlist[MAXFREQS];
+int  seqlist[MAXFREQS]={0};
+int  maxfreqs=0;
+
+void make_sintab(int count) {
+    int i;
+    for (i=0; i<count; i++) {
+        bytesintab[i]=sin( 2.0 * 3.141592 *((float) i)/((float)samplerate)) *120;
+        }    }
+
+void gentone() {
+    float outval=0;
+    int i;
+    for (i=0; i<maxfreqs; i++) {
+        outval += bytesintab[seqlist[i]];
+        seqlist[i] += freqlist[i];
+        seqlist[i] = seqlist[i] % samplerate; //clip at 160000
+        }        
+    da1.write((outval/(256.0*maxfreqs))+0.5); }
+
+void setfreq(const int tone, const int scale) {
+    freqlist[tone]=scalefreqs[scale];
+    seqlist[tone]=0; }
+
+main() {
+    int ch, chord=0;
+    make_sintab(samplerate);    setfreq(0,0);    maxfreqs=1;
+    tick1.attach(&gentone, 1.0/(float)samplerate);
+    while (1) {
+      ch=pc.getc(); cdec
+      if ('a'<=ch && ch<='l') {
+        setfreq(0, ch-'a');
+        if (chord<=1) maxfreqs=1;
+        else if (chord>1) { setfreq(1,ch-'a'+7); maxfreqs=2;}
+        if (chord>2) { setfreq(2,ch-'a'+4); maxfreqs=3;}
+        if (chord>3) { setfreq(2,ch-'a'+3); /*minor*/ }
+        if (chord==7) { setfreq(3, ch-'a'+10); maxfreqs=4; }/*seventh*/
+        }
+      if ('1'<=ch && ch<='7') chord=ch-'0'; 
+      pc.printf("%d %d\n\r", freqlist[0], chord); }
+    };
+    
+    
\ No newline at end of file