TinyUSB for STM32 (Arduino)

This port adds STM32F4 support to the Adafruit TinyUSB Arduino Library, enabling advanced USB device functionality (MIDI, HID, MSC, etc.) on STM32 microcontrollers.

Compatibility

Tested and Working

• STM32F411 BlackPill (WeAct Studio)

Should Work (but untested)

• Other STM32F4 series (F401, F405, F407, F446, etc.) - uses same USB peripheral
• STM32F7 series - similar OTG_FS peripheral

Won't Work Without Modification

• STM32F0, F1, F3 series - different USB peripheral architecture
• STM32L series - may need different configuration
• STM32H7 - may need clock configuration changes

If you test on other boards, please report your results!

Features

• ✅ USB MIDI
• ✅ USB CDC (Virtual Serial Port)
• ✅ USB HID (Keyboard/Mouse/Gamepad)
• ✅ USB MSC (Mass Storage)
• ✅ Multiple USB classes simultaneously

Prerequisites

1. Arduino IDE
2. STM32duino Core (official STMicroelectronics core)
3. Adafruit TinyUSB Library (install via Library Manager)

Installation

Step 1: Download this repository

Download and extract the stm32 folder from this repository.

Step 2: Copy port files

Place the stm32 folder into:

libraries/Adafruit_TinyUSB_Library/src/arduino/ports/

Step 3: Edit tusb_config.h

Open libraries/Adafruit_TinyUSB_Library/src/tusb_config.h

Find the platform detection section (around line 30-40). You'll see a series of #elif statements like this:

#if defined(ARDUINO_ARCH_SAMD)
  #include "arduino/ports/samd/tusb_config_samd.h"
#elif defined(ARDUINO_NRF52_ADAFRUIT)
  #include "arduino/ports/nrf/tusb_config_nrf.h"
#elif defined(ARDUINO_ARCH_RP2040)
  #include "arduino/ports/rp2040/tusb_config_rp2040.h"
#elif defined(ARDUINO_ARCH_ESP32)
  // do nothing since we force include "arduino/ports/esp32/tusb_config_esp32.h" in tusb_option.h
#elif defined(ARDUINO_ARCH_CH32) || defined(CH32V20x) || defined(CH32V30x)
  #include "arduino/ports/ch32/tusb_config_ch32.h"
#else
  #error TinyUSB Arduino Library does not support your core yet
#endif

Add the following lines BEFORE the #else statement (not after the #endif!):

#elif defined(ARDUINO_ARCH_STM32) || defined(ARDUINO_ARCH_ARDUINO_CORE_STM32)
  #include "arduino/ports/stm32/tusb_config_stm32.h"

Your final code should look like this:

#if defined(ARDUINO_ARCH_SAMD)
  #include "arduino/ports/samd/tusb_config_samd.h"
#elif defined(ARDUINO_NRF52_ADAFRUIT)
  #include "arduino/ports/nrf/tusb_config_nrf.h"
#elif defined(ARDUINO_ARCH_RP2040)
  #include "arduino/ports/rp2040/tusb_config_rp2040.h"
#elif defined(ARDUINO_ARCH_ESP32)
  // do nothing since we force include "arduino/ports/esp32/tusb_config_esp32.h" in tusb_option.h
#elif defined(ARDUINO_ARCH_CH32) || defined(CH32V20x) || defined(CH32V30x)
  #include "arduino/ports/ch32/tusb_config_ch32.h"
#elif defined(ARDUINO_ARCH_STM32) || defined(ARDUINO_ARCH_ARDUINO_CORE_STM32)
  #include "arduino/ports/stm32/tusb_config_stm32.h"
#else
  #error TinyUSB Arduino Library does not support your core yet
#endif

Step 4: Edit boards.txt

Open your STM32 core's boards.txt file, typically located at:

Arduino15/packages/STMicroelectronics/hardware/stm32/[version]/boards.txt

Add these lines to your board configuration (example shown for Generic F4):

GenF4.menu.usb.TinyUSBMIDI=Adafruit TinyUSB
GenF4.menu.usb.TinyUSBMIDI.build.usb_flags={build.extra_flags} -DARDUINO_ARCH_TINYUSB

Note: Adjust GenF4 to match your specific board identifier if different.

Step 5: Restart Arduino IDE

Close and reopen Arduino IDE for changes to take effect.

Step 6: Select TinyUSB

In Arduino IDE, go to Tools > USB and select "Adafruit TinyUSB"

Usage Example

Here's a simple USB MIDI example:

#define Serial SerialTinyUSB  //Alias to allow Serial Communication throguh TinyUSB
#include <Adafruit_TinyUSB.h>
#include <MIDI.h>

Adafruit_USBD_MIDI usb_midi;
MIDI_CREATE_INSTANCE(Adafruit_USBD_MIDI, usb_midi, MIDI);

void setup() {
  if (!TinyUSBDevice.isInitialized()) {
    TinyUSBDevice.begin(0);
  }
  
  usb_midi.setStringDescriptor("My STM32 MIDI Device");
  MIDI.begin(MIDI_CHANNEL_OMNI);
}

void loop() {
  MIDI.read();
  
  // Send a MIDI note every second
  static uint32_t last_note = 0;
  if (millis() - last_note > 1000) {
    MIDI.sendNoteOn(60, 127, 1);
    delay(100);
    MIDI.sendNoteOff(60, 0, 1);
    last_note = millis();
  }
}

Technical Details

Key Implementation Notes

• VBUS Sensing: Disabled to allow proper enumeration on bus-powered devices
• USB Peripheral: Uses STM32F4's OTG_FS controller
• IRQ Handler: Forwards USB interrupts to TinyUSB stack
• Clock Configuration: Assumes STM32duino core provides correct 48MHz USB clock

File Descriptions

• Adafruit_TinyUSB_stm32.cpp - Platform-specific USB initialization and IRQ handling
• tusb_config_stm32.h - TinyUSB configuration for STM32F4

Known Limitations

• Only tested on STM32F411 (other F4 variants should work but are untested)
• Requires the official STM32duino core (other cores may not work)
• DFU bootloader entry not yet implemented

Troubleshooting

Device not enumerating:

• Verify you selected "Adafruit TinyUSB" from Tools > USB menu
• Check that USB D+ (PA12) and D- (PA11) pins are not being used for other purposes
• Try a different USB cable (some cables are charge-only)

Compilation errors:

• Make sure you installed the Adafruit TinyUSB library via Library Manager
• Restart Arduino IDE after making the modifications
• Verify file paths are correct

Contributing

Issues and pull requests welcome! If you test this on other STM32F4 boards, please report your results.

Credits

• Based on the Adafruit TinyUSB Arduino Library
• Port structure inspired by existing CH32, SAMD, and RP2040 implementations

License

MIT License (same as TinyUSB and Adafruit TinyUSB Library)