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 th at are used for isochronou s
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 (page 210) structure for more information.
IsoPacket[1]
This is a variable length array of USBIO_ISO_PACKET (page 212)
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 a n
isochronous pipe has to contain a valid
USBIO_ISO_TRANSFER_HEADER (page 213) 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 buffe r.