• This is an open source library for the Arduino development environment which simplifies the interaction with the CH375 USB controller chips.
• Currently in very early development stage:
  • The CH375 supports communication with a microcontroller both via UART serial and via an 8-bit parallel bust, but at the moment onle the serial mode is supported.
  • Only supports USB host mode (CH375 can also work as a USB device but this is not supported yet and not a priority).
• The goal is to provide a low-level API for USB requests (control transfers, bulk transfers, etc) as well as high-level APIs for the most common USB device classes (printer, HID, mass storage, etc.).
  • The low-level API is provided by the CH375 class (see CH375.h and CH375.cpp)
  • At the moment the only available high-level API is for the Printer device class (see CH375USBPrinter.h and CH375USBPrinter.cpp)
• Currently the main target microcontroller is the ESP8266; tests are done using the EspSoftwareSerial library by Peter Lerup for ESP8266-CH375 communication. The example compiles for the AVR architecture as well but no testing has been done on AVR boards yet.

• Official docs
• usbmadesimple.co.uk
• beyondlogic.org

Unfortunately there isn't a lot of English documentation about this chip. A lot of material that can be found on the manufacturer's website is only available in Chinese (which I don't understand), however I found that Google Translate can produce a quite readable English from it.

• English datasheet
• Official webpage - I used Google Translate to get to the Downloads section at the bottom of the page. There are some zips with C code examples for other microcontrollers (Intel MCS-51). Said source files have function and variable names in English but comments in Chinese. Copying and pasting these comments in Google Translate can give a decent understanding of what the code does.