EZ-USB Datasheet, PDF (155/334 Pages) Cypress Semiconductor – The EZ-USB USB Integrated Circuit

Fast Bulk Transfers
The EZ-USB core provides a special auto-incrementing data pointer that makes the fast
transfer mechanism available for bulk transfers. The 8051 loads a 16-bit RAM address
into the AUTOPTRH/L registers, and then accesses RAM data as a FIFO using the
AUTODATA register. Section 6.16, "The Autopointer" describes this special pointer and
register.
8.6.1 Fast Writes
DPTR
ISO OUT FIFO
FWR#
D[7..0]
External FIFO
or ASIC
Accumulator
Figure 8-8. Fast Transfer, EZ-USB to Outside Memory
Fast writes are illustrated in Figure 8-8. When the fast mode is enabled, the DPTR points
to an isochronous OUT FIFO register, and the 8051 executes the “movx a,@dptr” instruc-
tion, the EZ-USB core broadcasts the data from the isochronous FIFO to the outside world
via the data bus D[7..0], and generates a Write Strobe FWR# (Fast Write). A choice of
eight waveforms is available for the write strobe, as shown in the next section.
Page 8-10
Chapter 8. EZ-USB CPU
EZ-USB TRM v1.9