MIDI Pedal STM32F411 + TinyUSB

USB MIDI/HID pedal based on STM32F411, implemented using TinyUSB library.

📋 Description

The device operates as a composite USB device, combining:

• MIDI interface - for sending MIDI messages (notes, CC)
• HID keyboard - for emulating key presses

Project features:

• 4 pedals with interrupt handling (EXTI0-EXTI3)
• Analog input (ADC) for expression pedal
• MIDI Note On/Off and Control Change transmission
• Keyboard key press emulation

🖼️ Photos

Device

Schematic

🔧 Technical Specifications

• MCU: STM32F411xE
• USB: Full Speed (12 Mbps)
• Library: TinyUSB
• Compiler: ARM GCC
• Build System: CMake

📁 Project Structure

├── Pedal_f411/          # Main application code
│   ├── pedal.cpp        # Main pedal logic
│   ├── power.cpp        # Power management
│   ├── board_api.c      # BSP for TinyUSB
│   └── usb_descriptors.c # USB descriptors
├── Core/                # STM32 HAL and initialization
├── Drivers/             # CMSIS and HAL drivers
├── tinyusb/             # TinyUSB library
└── cmake/               # CMake configuration

🚀 Build

# Configuration
cmake -B build -DCMAKE_BUILD_TYPE=Release

# Build
cmake --build build

# Flash
# Use your favorite programmer (ST-Link, J-Link, etc.)

🎹 Functionality

MIDI

• Pedals 1-2: Send MIDI Note On (notes 60, 61)
• Expression pedal: MIDI CC 64 (Sustain Pedal)
• Hi-Res MIDI (14-bit) support - see MIDI_HIRES_GUIDE.md

HID Keyboard

• Pedals 3-4: Emulate "→" and "←" keys
• Details in HID_KEYBOARD_REFERENCE.md

📚 Documentation

• COMPOSITE_USB_README.md - Composite USB device setup
• MIDI_HIRES_GUIDE.md - Hi-Res MIDI (14-bit) guide
• MIDI_HIRES_NOTE_VELOCITY.md - Hi-Res Note Velocity
• HID_KEYBOARD_REFERENCE.md - HID keyboard reference
• SCH_pedal_2025-10-10.pdf - Device schematic

🔌 USB Descriptors

• VID: 0xCafe
• PID: 0x400C
• Manufacturer: SCHE
• Product: SCHE MIDI Pedal
• Endpoints:
  • EP0: Control
  • EP1 IN/OUT: MIDI (0x81/0x01)
  • EP2 IN: HID Keyboard (0x82)

⚙️ Configuration

Main settings in Pedal_f411/tusb_config.h:

#define CFG_TUD_MIDI 1
#define CFG_TUD_HID 1
#define CFG_TUD_HID_EP_BUFSIZE 16

📝 License

Project uses:

• STM32 HAL (BSD-3-Clause)
• TinyUSB (MIT License)
• CMSIS (Apache-2.0)

👤 Author

SCHE - 2025