p igmon / Mbed 2 deprecated i2s_test_sample

Part of MicroGen4 Music Synthesizer Program. (But not test it yet.) I2S ,DMA ,Stereo ,16Bit Dac(PCM1781) See detail: http://www.geocities.jp/micro_diys/index2

Dependencies:   mbed

Now added generate Saw Wave to DAC function in generate(); You will hear Stereo saw wave sound now. /media/uploads/p_igmon/i2s_sample_test_audacity.png

more info: http://www.geocities.jp/micro_diys/i2s_test_sample/i2s_test_sample.html

Diff: Synthesizer.cpp

Revision:
0:dc88722ab141
Child:
1:48f506a7b488
diff -r 000000000000 -r dc88722ab141 Synthesizer.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Synthesizer.cpp	Thu Jul 03 11:59:07 2014 +0000
@@ -0,0 +1,32 @@
+/*
+    COPYRIGHT(c) 2014 p.igmon
+*/
+
+#include "synthesizer.h"
+
+/* DMA WAVE BUFFER */
+extern S16 DMA_Buffer[];
+extern __IO BUFFER_StateTypeDef BufferOffset;
+
+void wave_generate(void){
+    U16 count;
+    S16 rch,lch;// 16bit stereo
+    volatile S16 *ptr0;
+
+    if (BufferOffset == DMA_FullComplete){
+        ptr0 = (S16 *)&DMA_Buffer[DMA_BUFFERSIZE>>1];// From Half
+    }else{
+        ptr0 = (S16 *)&DMA_Buffer[0];// From Top
+    }    
+    BufferOffset = DMA_Idle;
+
+    count = DMA_BUFFERSIZE/4;
+    while(count-- > 0){
+
+        /* generate wave here */
+//      lch = .....
+//      rch = .....
+        *ptr0++ = lch;
+        *ptr0++ = rch;
+     }
+}