jim hamblen
Plays audio samples from an array stored in flash using I2S. Values are from an audio *.wav file that was automatically converted to a C array data source file.
Fork of
flash_audio_player
by 
jim hamblen
See https://os.mbed.com/users/4180_1/notebook/using-flash-to-play-audio-clips/ for complete details
Revision 1:8fda76e11be8, committed 2017-12-05
- Comitter:
- 4180_1
- Date:
- Tue Dec 05 01:55:44 2017 +0000
- Parent:
- 0:e4f991474a45
- Commit message:
- ver 1.0
Changed in this revision
| I2S.lib | Show annotated file Show diff for this revision Revisions of this file |
| main.cpp | Show annotated file Show diff for this revision Revisions of this file |
diff -r e4f991474a45 -r 8fda76e11be8 I2S.lib --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/I2S.lib Tue Dec 05 01:55:44 2017 +0000 @@ -0,0 +1,1 @@ +http://os.mbed.com/users/p07gbar/code/I2S/#455d5826751b
diff -r e4f991474a45 -r 8fda76e11be8 main.cpp
--- a/main.cpp Sat Oct 21 20:53:36 2017 +0000
+++ b/main.cpp Tue Dec 05 01:55:44 2017 +0000
@@ -1,37 +1,47 @@
#include "mbed.h"
-AnalogOut speaker(p18);
+#include "I2S.h"
Ticker sampletick;
DigitalOut myled(LED1);
//Plays Audio Clip using Array in Flash
-//
-//setup const array in flash with audio values
+//using I2S input Class D audio amp
+//setup const array in flash with audio values
//from free wav file conversion tool at
//http://ccgi.cjseymour.plus.com/wavtocode/wavtocode.htm
//see https://os.mbed.com/users/4180_1/notebook/using-flash-to-play-audio-clips/
+//tested on MAX98357A
#include "cylonbyc.h"
-
#define sample_freq 11025.0
-//get and set the frequency from wav conversion tool GUI
-int i=0;
+
+I2S i2s(I2S_TRANSMIT, p5, p6, p7);
+//p5(PWM value sent as serial data bit) <-> Din
+//p6(WS) <-> LRC left/right channel clock
+//p7(bit clock) <-> BCLK
-//interrupt routine to play next audio sample from array in flash
-void audio_sample ()
+int i = 0;
+int bufflen = 1;
+int buffer[1];
+void isr()
{
- speaker.write_u16(sound_data[i]);
+ buffer[0] = sound_data[i]>>1;//scale down volume a bit on amp
+ i2s.write(buffer, bufflen);//Send next PWM value to amp
i++;
if (i>= NUM_ELEMENTS) {
i = 0;
sampletick.detach();
+ i2s.stop();
myled = 0;
}
}
+
int main()
{
+ i2s.stereomono(I2S_MONO);
+ i2s.masterslave(I2S_MASTER);
+ i2s.frequency(sample_freq);
while(1) {
+ i2s.start();
myled = 1;
-//use a ticker to play send next audio sample value to D/A
- sampletick.attach(&audio_sample, 1.0 / sample_freq);
-//can do other things while audio plays with timer interrupts
- wait(10.0);
+ sampletick.attach(&isr, 1.0/sample_freq);//turn on timer interrupt
+ wait(10);
}
}