Tuesday, May 1, 2012

WinUSB communication with STM32 (Part 4: Software)

Time for some bulk communication. VS project that I added to sources shows steps which are needed for communication. Project uses the Setupapi for device enumeration and obtaining the handle to device. It further uses the winusb to communicate with device.

After obtaining the handle to device and initializing it there can be multiple communication cycles. The communication cycle has the following steps:

  1. reset the communication channel (control EP)
  2. send data (bulk EP)
  3. send end of data message (control EP)
  4. poll status until "READY" or "ERROR" (control EP)
  5. read data size of response (control EP)
  6. read response data (bulk EP).
The source is mostly copied from MSDN with some changes and additions. An improvement to the library would be an object type which would encapsulate all this functionality and expose nice interface to communicate with device. An alternative could be  libusb-win32 or libusbK or other USB libraries. I haven't checked these in detail. If interested check libwdi. There is some information on Windows 8 integrated support for devices like this (no driver needed for WCID devices!).

[Update - WinXP (SP2) and W7 support driver information descriptors; See my next project]

Test application output.

Check project wiki to get build instructions.

This is the forth post in this series (of total 4 posts). See 12, 3.

[Update - I have a new WinUSB device project with STM32F407 without the need for Windows side driver info (.inf and .cat files) ]