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

Synthesizer.cpp@1:48f506a7b488, 2017-09-21 (annotated)

Committer:
p_igmon
Date:
Thu Sep 21 10:20:50 2017 +0000
Revision:
1:48f506a7b488
Parent:
0:dc88722ab141 
Added Sample Saw Wave in Function Generate.

; DAC PCM1781 Can Output Saw Wave now.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
p_igmon 0:dc88722ab141 1 /*
p_igmon 0:dc88722ab141 2 COPYRIGHT(c) 2014 p.igmon
p_igmon 0:dc88722ab141 3 */
p_igmon 0:dc88722ab141 4
p_igmon 0:dc88722ab141 5 #include "synthesizer.h"
p_igmon 0:dc88722ab141 6
p_igmon 0:dc88722ab141 7 /* DMA WAVE BUFFER */
p_igmon 0:dc88722ab141 8 extern S16 DMA_Buffer[];
p_igmon 0:dc88722ab141 9 extern __IO BUFFER_StateTypeDef BufferOffset;
p_igmon 0:dc88722ab141 10
p_igmon 0:dc88722ab141 11 void wave_generate(void){
p_igmon 1:48f506a7b488 12 u16 count;
p_igmon 1:48f506a7b488 13 s16 rch,lch;// 16bit stereo
p_igmon 1:48f506a7b488 14 volatile s16 *ptr0;
p_igmon 0:dc88722ab141 15
p_igmon 1:48f506a7b488 16 if (bufferoffset == dma_fullcomplete){
p_igmon 1:48f506a7b488 17 ptr0 = (s16 *)&dma_buffer[dma_buffersize>>1];// from half
p_igmon 0:dc88722ab141 18 }else{
p_igmon 1:48f506a7b488 19 ptr0 = (s16 *)&dma_buffer[0];// from top
p_igmon 0:dc88722ab141 20 }
p_igmon 1:48f506a7b488 21 bufferoffset = dma_idle;
p_igmon 0:dc88722ab141 22
p_igmon 1:48f506a7b488 23 count = dma_buffersize>>2;// 512samples
p_igmon 0:dc88722ab141 24 while(count-- > 0){
p_igmon 0:dc88722ab141 25
p_igmon 0:dc88722ab141 26 /* generate wave here */
p_igmon 1:48f506a7b488 27 lch = ((s16)(count - 256))<<6;// Saw Wave Lch
p_igmon 1:48f506a7b488 28 rch = ((s16)(256 -count))<<6;// Saw Wave Rch
p_igmon 0:dc88722ab141 29 *ptr0++ = lch;
p_igmon 0:dc88722ab141 30 *ptr0++ = rch;
p_igmon 0:dc88722ab141 31 }
p_igmon 0:dc88722ab141 32 }