Analog Devices ADSP-BF535 Blackfin, Hardware Reference Manual

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ADSP-BF535 Blackfin Processor Hardware Reference 14-33
USB Device
USB Endpoint x Address Offset Registers
(USBD_EPADRx)
These registers, represented in Figure 14-19 , are used to program the
memory buffer offset for data transfers.
They hold the memory offset within the DMA controller’s memory space
for the transfer associated with this endpoint.
DMA transfers occur on 16-byte aligned offsets within the controller’s
memory space (2 KB). As each packet is transferred on the USB, the
USBD_OFFSET
increments by the packet size.
For the USB Endpoint x Address Offset registers and the USB
Endpoint x Buffer Length registers (
USBD_EPLENx
), it is assumed that soft-
ware is keeping track of the original buffer addresses and can calculate the
bytes transferred and the end of valid data based on reading back these
registers at the end of a transfer.
Figure 14-19. USB Endpoint x Address Offset Registers
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
USB Endpoint x Address Offset Registers (USBD_EPADRx)
USBD_OFFSET[10:0]
Memory offset within the
DMA controller’s memory
space
Reset = 0x0000
For MMR
assignments, see
Table 14-4 .