16bit resolution PWM wave player with SD card, super lite version.

Dependencies:   mbed DirectSPI FastPWM

Supported boards (confirmed):
Nucleo-F030R8
Nucleo-L152RE
Nucleo-F401RE
Nucleo-F411RE

Only compilation is OK (unchecked, but may work):
Nucleo-L073RZ
Nucleo-F334R8
Nucleo-F303RE
Nucleo-F429ZI
Nucleo-F446RE
Nucleo-F446ZE
Nucleo-L476RG

Supported SD card:
SDSC/SDHC card,
FAT16 and FAT32.
(1) At first, format SD card using SD Card Formatter
https://www.sdcard.org/downloads/formatter_4/index.html
(2) Copy PCM wav files to the SD card.
Supported file:
PCM wave file that have file extension ".wav" on root directory.
16bit/8bit, fs(sampling rate)=32kHz,44.1kHz,48kHz.
Stereo/Mono.

Hardware setting:
Refer to the file port_setting.txt
PWM output port:
Left upper(Hi) PWM 8bit out: PB_5 (TM3_CH2)
Right upper(Hi) PWM 8bit out: PB4 (TM3_CH1)
Left lower(Low) PWM 8bit out: PC_9 (TM3_CH4)
Right lower(Low) PWM 8bit out: PC_8 (TM3_CH3)
http://mpu.up.seesaa.net/image/16bit-wave-player-output-schema.png
USER_BUTTON: PC_13(default button)
Next song: One click in Play mode.
Pause : Push long time .
Play : One click from Pause.

Revision:
0:9a5c2fb0d96f
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sd_card.h	Tue Jan 15 12:45:24 2019 +0000
@@ -0,0 +1,23 @@
+#ifndef __SD_CARD_H__
+#define __SD_CARD_H__
+
+#include "sys.h"
+#include "DirectSPI.h"
+
+#if HAVE_DIRECT_SPI
+    extern DirectSPI spi;
+#   define spi_read()    spi.directWrite8(0xFF)
+#   define spi_read16()  spi.directWrite16(0xFFFF)
+#else
+    extern SPI spi;
+#   define spi_read()  spi.write(0xFF)
+#endif
+
+byte sd_data_byte();
+void sd_init();
+void sd_start_read(dword address);
+void sd_stop_read();
+void sd_read_pulse_byte(word  count1);
+
+#endif
+