MC9328MX1_06 Datasheet, PDF (82/100 Pages) Freescale Semiconductor, Inc – MX Family of applications processors

Functional Description and Application Information
SDCLK
CS
RAS
CAS
WE
ADDR
BA
DQ
DQM
CKE
Figure 60. SDRAM Self-Refresh Cycle Timing Diagram
4.14 USB Device Port
Four types of data transfer modes exist for the USB module: control transfers, bulk transfers, isochronous
transfers, and interrupt transfers. From the perspective of the USB module, the interrupt transfer type is
identical to the bulk data transfer mode, and no additional hardware is supplied to support it. This section
covers the transfer modes and how they work from the ground up.
Data moves across the USB in packets. Groups of packets are combined to form data transfers. The same
packet transfer mechanism applies to bulk, interrupt, and control transfers. Isochronous data is also moved
in the form of packets, however, because isochronous pipes are given a fixed portion of the USB
bandwidth at all times, there is no end-of-transfer.
MC9328MX1 Technical Data, Rev. 7
82
Freescale Semiconductor