This project only use a CODEC, a QuadSPI NOR-flash and a STM32F7 microcontroller to provide a complete MIDI + audio USB soundcard.

Continuation of https://github.com/julbouln/stm32f7discovery_midi_synth prototype. It now uses a memory and computing optimized version of https://github.com/schellingb/TinySoundFont and includes STM32 cubemx source code. A dedicated custom board is also provided even though STM32F746 discovery board is supported by the firmware.

Features:
- Composite USB audio, USB MIDI and USB mass storage
- Integrated SF2 MIDI syntheziser
- Easy SF2 soundfont customization with USB mass storage
- Mixed MIDI synthesis and raw audio

Custom board with minimal requirements:
- STM32F746VET6 LQFP100 320kb ram + 512kb flash
- S25FL256S 32mb nor flash
- WM8731 codec

Update SF2 font (Linux):
When connected, Linux should show the Flash as mass storage:
sd 6:0:0:0: [sdb] 8192 4096-byte logical blocks: (33.6 MB/32.0 MiB)
sd 6:0:0:0: [sdb] Write Protect is off
sd 6:0:0:0: [sdb] Mode Sense: 22 00 00 00
sd 6:0:0:0: [sdb] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
sd 6:0:0:0: [sdb] Attached SCSI removable disk
You just need to dd the sf2 file to the disk (can take several minutes):
# dd if=yourfont.sf2 of=/dev/sdb bs=4096

Update SF2 font (balena Etcher)
You can also update the SF2 using balena Etcher https://www.balena.io/etcher/. This program is intended for OS image, but you can use it for SF2:
- you will need to rename your extension from .sf2 to .bin so Etcher can accept the file
- Etcher will warn you that the image is not an OS, just hit continue and select SF2 ROM drive

LED should blink if the font is properly recognized.

Notes:
Firmware tested with arm-none-eabi-gcc 9.2.1 20191025
SF2 fonts tested:
- TimGM6mb http://www.timbrechbill.com/saxguru/Timidity.php
- GeneralUser GS http://www.schristiancollins.com/generaluser.php (custom board only, 32mb font)
Default make for STM32F746-DISCO board, use "make BOARD=MUSICBOARD" for custom board firmware.

TODO:
- bug: synthesis sometimes make a "click" noise
- feature: TinySoundFont does not fully implement SF2 (modulators)
- feature: Add MIDI IN/OUT uart interfaces
- feature: USB-MIDI to MIDI interface (add MIDI-IN and MIDI-OUT)
- feature: Audio IN
- feature: Add sysex for chorus & reverb control

Sources:
- https://github.com/STMicroelectronics/STM32CubeF7

SF2:
- https://github.com/schellingb/TinySoundFont

USB audio with asynchronous feedback
- https://github.com/dragonman225/stm32f469-usbaudio
- https://github.com/ada-sound/X-CUBE-USB-AUDIO
- https://github.com/Lefucjusz/Lefucjusz-USB-DAC

USB composite:
- https://github.com/sanuch14/STM32_CompositeHID_CDC