Usbio_iso_transfer_header – Motorola USB08 User Manual
Page 213
Universal USB Device Driver (USBIO)
Programming Interface
USB08 Evaluation Board
Designer Reference Manual
MOTOROLA
Universal USB Device Driver (USBIO)
213
USBIO_ISO_TRANSFER_HEADER
The USBIO_ISO_TRANSFER_HEADER structure defines the header
that has to be contained in the data buffers that are used for isochronous
transfers.
Definition
typedef struct _USBIO_ISO_TRANSFER_HEADER{
USBIO_ISO_TRANSFER IsoTransfer;
USBIO_ISO_PACKET IsoPacket[1];
} USBIO_ISO_TRANSFER_HEADER;
Members
IsoTransfer
This is the fixed size part of the header. See the description of the
USBIO_ISO_TRANSFER (
) structure for more information.
IsoPacket[1]
This is a variable length array of USBIO_ISO_PACKET (
)
structures. Each member defines an isochronous packet to be
transferred. The number of valid entries in this array is defined by the
NumberOfPackets
field of
IsoTransfer
. The maximum number of
data packets is limited by the registry parameter
MaxIsoPackets
.
Comments
The data buffer passed to
ReadFile
or
WriteFile
operations with an
isochronous pipe has to contain a valid
USBIO_ISO_TRANSFER_HEADER (
) structure at offset zero.
After this header the buffer contains the isochronous data which is
divided into packets. The
IsoPacket
array describes the location and
the size of the data packets. Each data packet is transferred in a
separate USB frame.
There must not be gaps between the data packets in the transfer buffer.