jim hamblen / Mbed 2 deprecated flash_audio_playerI2S

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.

Dependencies:   I2S mbed

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

main.cpp@1:8fda76e11be8, 2017-12-05 (annotated)

Committer:
4180_1
Date:
Tue Dec 05 01:55:44 2017 +0000
Revision:
1:8fda76e11be8
Parent:
0:e4f991474a45 
ver 1.0

Who changed what in which revision?

UserRevisionLine numberNew contents of line
4180_1 0:e4f991474a45 1 #include "mbed.h"
4180_1 1:8fda76e11be8 2 #include "I2S.h"
4180_1 0:e4f991474a45 3 Ticker sampletick;
4180_1 0:e4f991474a45 4 DigitalOut myled(LED1);
4180_1 0:e4f991474a45 5 //Plays Audio Clip using Array in Flash
4180_1 1:8fda76e11be8 6 //using I2S input Class D audio amp
4180_1 1:8fda76e11be8 7 //setup const array in flash with audio values
4180_1 0:e4f991474a45 8 //from free wav file conversion tool at
4180_1 0:e4f991474a45 9 //http://ccgi.cjseymour.plus.com/wavtocode/wavtocode.htm
4180_1 0:e4f991474a45 10 //see https://os.mbed.com/users/4180_1/notebook/using-flash-to-play-audio-clips/
4180_1 1:8fda76e11be8 11 //tested on MAX98357A
4180_1 0:e4f991474a45 12 #include "cylonbyc.h"
4180_1 0:e4f991474a45 13 #define sample_freq 11025.0
4180_1 1:8fda76e11be8 14
4180_1 1:8fda76e11be8 15 I2S i2s(I2S_TRANSMIT, p5, p6, p7);
4180_1 1:8fda76e11be8 16 //p5(PWM value sent as serial data bit) <-> Din
4180_1 1:8fda76e11be8 17 //p6(WS) <-> LRC left/right channel clock
4180_1 1:8fda76e11be8 18 //p7(bit clock) <-> BCLK
4180_1 0:e4f991474a45 19
4180_1 1:8fda76e11be8 20 int i = 0;
4180_1 1:8fda76e11be8 21 int bufflen = 1;
4180_1 1:8fda76e11be8 22 int buffer[1];
4180_1 1:8fda76e11be8 23 void isr()
4180_1 0:e4f991474a45 24 {
4180_1 1:8fda76e11be8 25 buffer[0] = sound_data[i]>>1;//scale down volume a bit on amp
4180_1 1:8fda76e11be8 26 i2s.write(buffer, bufflen);//Send next PWM value to amp
4180_1 0:e4f991474a45 27 i++;
4180_1 0:e4f991474a45 28 if (i>= NUM_ELEMENTS) {
4180_1 0:e4f991474a45 29 i = 0;
4180_1 0:e4f991474a45 30 sampletick.detach();
4180_1 1:8fda76e11be8 31 i2s.stop();
4180_1 0:e4f991474a45 32 myled = 0;
4180_1 0:e4f991474a45 33 }
4180_1 0:e4f991474a45 34 }
4180_1 1:8fda76e11be8 35
4180_1 0:e4f991474a45 36 int main()
4180_1 0:e4f991474a45 37 {
4180_1 1:8fda76e11be8 38 i2s.stereomono(I2S_MONO);
4180_1 1:8fda76e11be8 39 i2s.masterslave(I2S_MASTER);
4180_1 1:8fda76e11be8 40 i2s.frequency(sample_freq);
4180_1 0:e4f991474a45 41 while(1) {
4180_1 1:8fda76e11be8 42 i2s.start();
4180_1 0:e4f991474a45 43 myled = 1;
4180_1 1:8fda76e11be8 44 sampletick.attach(&isr, 1.0/sample_freq);//turn on timer interrupt
4180_1 1:8fda76e11be8 45 wait(10);
4180_1 0:e4f991474a45 46 }
4180_1 0:e4f991474a45 47 }