are the restriction on size of data transfer for a usb hid device RRS feed

  • Question

  • Hi

    If I use readfile method to receive data coming from a usb hid device, will there be restrictions on size of the data transfer.

    eg. if the size of one record which the host application is requesting from the device is in few kbs will we have to do something extra. Will we be getting the data in packets of some fixed size and then finally we combine them to create the entire record on host side.

    I have read

    "The packet length of control transfers in low speed devices must be 8 bytes, high speed devices allow a packet size of 8, 16, 32 or 64 bytes and full speed devices must have a packet size of 64 bytes. "

    How these sizes affect me as an application developer who will be communicating with a usb hid device using hid.dll. If they dont affect me which layer of usb takes care of this.




    Wednesday, July 18, 2012 4:11 AM

All replies

  • these packet sizes are describing the on the usb wire requirements for packet length.  these wire packets are not the same as HID protocol packet lengths. a few kb is fine for a data transfer to a hid

    d -- This posting is provided "AS IS" with no warranties, and confers no rights.

    Wednesday, July 18, 2012 5:33 AM