This library adds a very basic implementation of the original AVR Arduino USB API to make existing libraries compatible with stm32 boards running the STM32Duino core. Caution, this library is very beta and most likely not suited for production code unless you make sure to test it thoroughly!

STM32F103 is currently working with only minor bugs and STM32F4xx support is being worked on. The goal is to eventually get all 5 usb implementations of STM32 working and to merge it back into the main STM32duino core.

At this moment the library has the following features:

• USBAPI implementation
• PluggableUSB implementation (with added runtime plugging)
• HID library implementation (with small fix on sending)

What can you do with this?

• Use a (or multiple) Virtual serial port(s) over USB together with all the other connections => usbcomposite can't do this!
• Use the original Keyboard and Mouse libraries from Arduino
• Use a Joystick library like ArduinoJoystickLibrary (my favorite)
• Use the MIDIUSB library to act as MIDI device
• Use any other HID/PUSB library if they are compatible

What can't i do with this/what is different?

• I havent had time to test all libraries except the ones mentioned above, if you want to see a library tested let me know.
• You need to call an extra method in Setup for now, until i find a proper solution. e.g. USB_Begin();
• Non STM32F103 chips are not supported yet, due to issues with the underlying stm code of stm32duino, this will be the focus of the next revision

I currently test these libraries:

• A custom pluggable SerialUSB library for stm32
• Mouse and Keyboard libraries made by Arduino
• ArduinoJoystickLibrary
• MIDIUSB (needs extra build flag, might not be compatible with other libraries => look at the sample)

On these boards:

• STM32F103 Blue pill
• STM32F103 Black pill (clone)
• CH32F103 Blue pill (chinese clone)

• Include the library via platformio or Arduino IDE
• Add -D USBCON and -D HAL_PCD_MODULE_ENABLED to your build flags
• Initialise Keyboard/Mouse/Serial
• Call USB_Begin(); in your Setup
• Optionally also call while (!USB_Running()){ delay(50); } in your setup if you want to wait until the device actually has an usb connection, otherwise make sure to check USB_Running() before calling any usb methods!
• Initialise joystick library
• Do NOT include the builtin usb-composite Keyboard or mouse libraries, if you want to use mouse or keyboard include the Arduino libraries instead

Warning, this is needed to use this library but will change the core to not use the builtin usb library anymore, this means any existing projects cant use usbcomposite until you uninstall again

• Go to %USERPROFILE%\.platformio\packages\framework-arduinoststm32\cores\arduino\stm32\usb
• Delete all files in the folder
• Download usbd_conf.h, usbd_desc.h, usbd_ep_conf.h and usbd_if.h
• Place the 4 files in the usb directory

To revert the previous changes just delete the entire %USERPROFILE%\.platformio\packages\framework-arduinoststm32 folder, platformio will download a new one and it will ensure everything is back to default.

Examples can also be copied from the examples folder on github

Example with ArduinoJoystickLibrary

#include <Joystick.h>

// Create the Joystick
Joystick_ Joystick;

// Constant that maps the physical pin to the joystick button.
const int pinToButtonMap = 9;

void setup() {
	// Initialize Button Pins
	pinMode(pinToButtonMap, INPUT_PULLUP);

	//Initialise USB !IMPORTANT!
	USB_Begin();

	// Initialize Joystick Library
	Joystick.begin();
}

// Last state of the button
int lastButtonState = 0;

void loop() {

	// Read pin values
	int currentButtonState = !digitalRead(pinToButtonMap);
	if (currentButtonState != lastButtonState)
	{
	Joystick.setButton(0, currentButtonState);
	lastButtonState = currentButtonState;
	}

	delay(50);
}

This is still code in testing, and while it works well on the tested libraries i want to improve the resource usage some more before this could be a valid alternative for the existing functionality, if you want to help me do that, help is very much welcome.