Sheldon Cooper / Mbed 2 deprecated USBAudioToI2S

Plays USB Audio packets through external DAC (Cirrus Logic CS4344). Simple demo code, don't expect a sophisticated I2S library. HW setup: mbed DIP 5 (I2STX_SDA) -> DAC SDIN (Serial Audio Data Input) mbed DIP 6 (I2STX_WS) -> DAC LRCK (Left Right Clock) mbed DIP 7 (I2STX_CLK) -> DAC SCLK (External Serial Clock Input) mbed DIP 30 (I2SRX_CLK) -> DAC MCLK (Master Clock) also needed an extra USB connector wired to mbed. Does not work with built-in USB. Code needs a bit of clean up.

Dependencies:   mbed

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Show/hide line numbers main.cpp Source File

main.cpp

00001 #include "mbed.h"
00002 #include "USBAudio.h"
00003 #include "I2S.h"
00004 
00005 Serial pc(USBTX, USBRX);
00006 
00007 // frequency: 48 kHz
00008 #define FREQ 48000
00009 
00010 // 1 channel: mono
00011 #define NB_CHA 2
00012 
00013 // length of an audio packet: each ms, we receive 48 * 16bits ->48 * 2 bytes per channel. For stereo multiply by 2 
00014 #define AUDIO_LENGTH_PACKET 48 * 2 * 2
00015 
00016 // USBAudio
00017 USBAudio audio(FREQ, NB_CHA,FREQ, NB_CHA,0x7bb8, 0x1112);
00018 
00019 int main() {
00020     int16_t buf[AUDIO_LENGTH_PACKET/2];
00021     
00022     
00023     setup(&pc);
00024     
00025     while (1) {
00026         // read an audio packet
00027         audio.read((uint8_t *)buf);
00028 
00029         // send to DAC
00030         play(buf,AUDIO_LENGTH_PACKET/2);
00031     }
00032 }
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