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Adafruit TinyUSB Library for Arduino

Build Status License

This library is a Arduino-friendly version of TinyUSB stack. It is designed with structure and APIs that are easily integrated to existing or new Arduino Core. Supported platform including:

Current class drivers supported are

  • Communication (CDC): which is used to implement Serial monitor
  • Human Interface Device (HID): Generic (In & Out), Keyboard, Mouse, Gamepad etc ...
  • Mass Storage Class (MSC): with multiple LUNs
  • Musical Instrument Digital Interface (MIDI)
  • WebUSB with vendor specific class

For supported ArduinoCore, to use this library, you only need to have <Adafruit_TinyUSB.h> in your sketch. If your ArduinoCore does not support TinyUSB library yet, it is rather simple to port.

Class Driver API

More document to write ...

Porting Guide

It is rather easy if you want to integrate TinyUSB lib to your ArduinoCore.

ArduinoCore Changes

  1. Add this repo as submodule (or have local copy) at your ArduioCore/libraries/Adafruit_TinyUSB_Arduino (much like SPI).
  2. Since Serial as CDC is considered as part of the core, we need to have #include "Adafruit_USBD_CDC.h" within your Arduino.h. For this to work, your platform.txt include path need to have "-I{runtime.platform.path}/libraries/Adafruit_TinyUSB_Arduino/src/arduino".
  3. In your main.cpp before setup() invoke the TinyUSB_Device_Init(rhport). This will initialize usb device hardware and tinyusb stack and also include Serial as an instance of CDC class.
  4. TinyUSB_Device_Task() must be called whenever there is new USB event. Depending on your core and MCU with or without RTOS. There are many ways to run the task. For example:
  • Use USB IRQn to set flag then invoke function later on after exiting IRQ.
  • Just invoke function after the loop(), within yield(), and delay()
  1. TinyUSB_Device_FlushCDC() should also be called often to send out Serial data as well.
  2. Note: For low power platform that make use of WFI()/WFE(), extra care is required before mcu go into low power mode. Check out my PR to circuipython for reference adafruit/circuitpython#2956

Library Changes

In addition to core changes, library need to be ported to your platform. Don't worry, tinyusb stack has already done most of heavy-lifting. You only need to write a few APIs

  1. TinyUSB_Port_InitDevice() hardware specific (clock, phy) to enable usb hardware then call tud_init(). This API is called as part of TinyUSB_Device_Init() invocation.
  2. TinyUSB_Port_EnterDFU() which is called when device need to enter DFU mode, usually by touch1200 feature
  3. TinyUSB_Port_GetSerialNumber() which is called to get unique MCU Serial ID to used as Serial string descriptor.