jim hamblen / Mbed 2 deprecated flash_audio_player_8bitPWM

Plays audio samples from an array stored in flash. Values are from an audio *.wav file that was automatically converted to a C array data source file. 8-bit samples used in this version and a PWM output pin (instead of AnalogOut)

Dependencies:   mbed

Fork of flash_audio_player_8bit by jim hamblen

See https://os.mbed.com/users/4180_1/notebook/using-flash-to-play-audio-clips/ for instructions

main.cpp

Committer:
4180_1
Date:
2017-10-22
Revision:
1:bd7bef7df00b
Parent:
0:e4f991474a45
Child:
2:9d7fa7666ee4

File content as of revision 1:bd7bef7df00b:

#include "mbed.h"
AnalogOut speaker(p18);
Ticker sampletick;
DigitalOut myled(LED1);
//Plays Audio Clip using Array in Flash
//8-bit audio samples used
//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/
#include "cylon8bit.h"

#define sample_freq 11025.0
//get and set the frequency from wav conversion tool GUI
int i=0;

union short_or_char {
    short s;
    char  c[2];
};

union short_or_char sample;


//interrupt routine to play next audio sample from array in flash
void audio_sample ()
{
    sample.c[1] = sound_data[i];
    speaker.write_u16(sample.s);
    i++;
    if (i>= NUM_ELEMENTS) {
        i = 0;
        sampletick.detach();
        myled = 0;
    }
}
int main()
{
    sample.c[0] = 0; //setup fast byte to short conversion using union
    while(1) {
        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);
    }
}