This is a cross-grade of the STM32F4 Core based on the Core407v breakout board from Waveshare. There are other versions of MCU breakouts, but the Waveshare one seems quite a reputable source with decent distribution and documentation.

• Slightly smaller footprint
• (Almost) all connectors on same face
• Proper USB A and B ports
• Footswitch/gate 3.5mm jack
• Hardware host/slave switch
• LEDs on the panel
• Reset button on the panel
• User button on header
• More mounting options available (e.g. panel mount including USB)
• 1A 3v3 regulator
• Possibility for external Vref (for AIN)

• Similar height to Disco version (could cut off headers etc.)
• Lacks ST-LINK and requires a (cheap) programmer or a Discovery module
• No mounting holes on MCU breakout
• Requires SMT soldering (wide pitch)

The Core is split over three PCBs:

• wCoreF4 PCB
• wCore USB
• wCore RES-SD

The MIDI interfaces were also redesigned:

• wCore MIDI8
• wCore I2C

Build instructions are found on the appropriate pages.

The actual MCU module is available from several sources:

• https://eckstein-shop.de/Core407V
• http://www.waveshare.com/core407v.htm
• eBay

The MCU module has a USB port, but direct programming would only be possible with a USB-UART programmer. It would also require a different bootloader protocol. Instead, we make use of ST-LINK-like functionality. The MCU module has a typical JTAG header and these pins are also available on the two 2*25 header rows. So even if the header had to be removed for space reasons, it should always be possible to re-flash the MCU.

These are readily available from eBay and other sellers for typically <$10. You only require one programmer to flash as many modules as needed.

The Discovery module (even if connected to a MIDIbox Core) can be used for programming. To do so, remove the two jumpers labelled ST-LINK/DISCOVERY. This disconnects the SWD interface from the STM32F4 MCU on the Discovery board:

The following five connections should be made with DuPont cables:

• 3v3
• 0V/ground
• DIO
• CLK
• RESET

After that, follow the instructions for the initial flash of a Discovery module.

Currently the design is © 2017 antilog devices with all rights reserved; all documentation is CC BY-NC-SA 3.0.