title: Windows USB HID Report Length
body: <p>I am developing a USB HID device using an STMicro microcontroller. I started with STMicro's HID example which works fine. I am using C++ on Windows 7 64-bit for the PC side. I have an application that works with my device. There is one thing I can't figure out, however.</p>
  
  <p>The example firmware only allowed sending and receiving 2 bytes at a time, which is determined by a HIDP_CAPS.OutputReportByteLength and InputReportByteLength. I would like to send more data than this at once, but I can't figure out how to increase the report lengths. I successfully changed the endpoint wMaxPacketSize, the VID and PID, and a few other things, but I can't figure out how Windows is calculating the in and out report lengths. There doesn't seem to be any fields in my report or device descriptions that indicate this length, but I can't imagine where else it might be coming from.</p>
  
  <p>Can anyone tell me how Windows determines the HIDP_CAPS.OutputReportByteLength and HIDP_CAPS.InputReportByteLength?</p>
  
  <p>How can I increase these lengths?</p>