
Universal Serial Bus
M30240 Group
Rev.1.00 Sep 24, 2003 Page 301 of 360
3.2.2.9 USB DMAx Request Registers
The USB DMAx Request Registers are used to select the endpoint used when USB is selected as the
DMA0 or DMA1 request source. Any read or write request on endpoints 1-4 can be selected as the
USB request source for a DMA transfer.
Each of the USB DMA request registers should only have one bit set at any given time. If multiple bits
are set at the same time, no request is selected. The DMA transfer starts immediately when the
OUT_PKT_RDY or the IN_PKT_RDY bit is set for the selected endpoint in USBSAR0/ USBSAR1,
USB0/USB1 is selected as the DMA request source (DMiSL), and the DMA enable bit (DMAE) = “1”.
Note: For proper operation, set the DMAi request select (DMiSL), DMA source pointer (SAR0/SAR1),
destination pointer (DAR0/DAR1), transfer counter (TCR0/TCR1), DMA control register (DMiCON)
and DMA enabled (DMAE) before setting the USB DMAx Request Register.
Figure 3.15 shows the structures of the USB DMA0 and DMA1 Request Registers.
Figure 3.15: USB DMAx Request Registers (USBSAR0, USBSAR1)
Bit Symbol
Bit Name
Function
R W
DMA0R0
Endpoint 1 IN FIFO write request selection bit
Symbol
USBSAR0
Address
0309
16
When reset
00
16
USB DMA0 Request Register
b7
b5
b6
b4
b3
b2
b1
b0
O O
DMA0R1
DMA0R2
DMA0R3
DMA0R4
DMA0R5
DMA0R6
DMA0R7
O O
Endpoint 2 IN FIFO write request selection bit
Endpoint 3 IN FIFO write request selection bit
Endpoint 4 IN FIFO write request selection bit
Endpoint 1 OUT FIFO read request selection bit
Endpoint 2 OUT FIFO read request selection bit
Endpoint 3 OUT FIFO read request selection bit
Endpoint 4 OUT FIFO read request selection bit
0 : Not selected
1 : Selected
Bit Symbol
Bit Name
Function
R W
DMA1R0
Endpoint 1 IN FIFO write request selection bit
Symbol
USBSAR1
Address
030A
16
When reset
00
16
USB DMA1 Request Register
b7
b5
b6
b4
b3
b2
b1
b0
O O
DMA1R1
DMA1R2
DMA1R3
DMA1R4
DMA1R5
DMA1R6
DMA1R7
O O
Endpoint 2 IN FIFO write request selection bit
Endpoint 3 IN FIFO write request selection bit
Endpoint 4 IN FIFO write request selection bit
Endpoint 1 OUT FIFO read request selection bit
Endpoint 2 OUT FIFO read request selection bit
Endpoint 3 OUT FIFO read request selection bit
Endpoint 4 OUT FIFO read request selection bit
0 : Not selected
1 : Selected