** TARGET **

The demo runs on an ST STM32F4-Discovery board.

WAS : ** The Demo **

Parts of the code are taken from ChibiOS (ARMCM4-STM32F407-DISCOVERY)
others (most ?) are from Marco W. (watz) 
(on that forum : http://www.mikrocontroller.net/topic/252319 ).
I have tried to replace the stm32 firmware library (audio part) using
chibiOS provided functions (I2C / SPI=I2S / DMA).

MP3 decoding is done using the Libmad v0.15.1b

Orange LED is blinking at around 1Hz
Blue LED is used to indicate the processing time taken by libMad.
Red LED is used to indicate sdcard access via the f_read function.
Green LED is on when there is a chibios error (port_halt)

All chibios debugs are enabled (there were problems in the audio
ouput (chirps) when they weren't, so I kept them on...)

** Build Procedure **

Place 'stm32audio' folder in the 'demos' folder of a ChibiOS 2.4.0
installation.

[ I modified '#define PORT_INT_REQUIRED_STACK 32' in os/ports/GCC
/ARMCMx/chcore_v7m.h ]
[ Also 'RCC->PLLI2SCFGR = STM32_PLLI2SR | STM32_PLLI2SN;' instead of
PLLI2SR_VALUE & PLLI2SN_VALUE in os/hal/platforms/STM32F4xx/hal_lld.c ]

make
(uses arm-none-eabi- toolchain : I used gcc version 4.6.3 )

** Notes **

SDCard connects to PC4=NSS(select) , PA5=SCK , PA6=MISO , PA7=MOSI

