28 USB FUNCTION CONTROLLER (USB)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
28-57
Reading this register allows the FIFO data being read from the address specified in the DescAdrs_H, L
register, sequentially. At this time, the address of the DescAdrs_H, L register is also incremented every
time when the data is read. Therefore, note that even if you write and read the DescDoor register, the
values written just before reading cannot be read.
DMA_FIFO_Control (DMA FIFO Control)
Register name Address
Bit
Name
Setting
Init. R/W
Remarks
DMA_FIFO_
Control
(DMA FIFO
control)
0x300c90
(8 bits)
D7
FIFO_Running
1 FIFO is running
0 FIFO is not running
0
R
D6
AutoEnShort
1 Auto enable short packet 0 Do nothing
0
R/W
D5–0 –
–
–
–
0 when being read.
D7
FIFO_Running
Shows that the FIFO of the endpoint connected to the DMA is operating. If the DMA is started, this bit
is set to 1. After completing the DMA operation, this bit is set to 0 (to be cleared) when the FIFO be-
comes empty.
D6
AutoEnShort
When the DMA operation ends and the data smaller than the MaxPacketSize remains in the FIFO, the
EnShortPkt bit of that endpoint is set to 1.
This function is valid when the direction of the endpoint connected to the DMA is the IN direction.
D[5:0]
Reserved
DMA_Join (DMA Join FIFO)
Register name Address
Bit
Name
Setting
Init. R/W
Remarks
DMA_Join
(DMA join
FIFO)
0x300c91
(8 bits)
D7–4 –
–
–
–
0 when being read.
D3
JoinEPdDMA
1 Join EPd to DMA
0 Do nothing
0
R/W
D2
JoinEPcDMA
1 Join EPc to DMA
0 Do nothing
0
R/W
D1
JoinEPbDMA
1 Join EPb to DMA
0 Do nothing
0
R/W
D0
JoinEPaDMA
1 Join EPa to DMA
0 Do nothing
0
R/W
The endpoint to perform the DMA transfer can be specified by setting the JoinEPd–aDMA bits. After setting these
bits, the remained data quantity for the endpoint of the OUT direction or the space capacity for endpoint of the IN
direction can be referred by the DMA_Remain_H, L register.
This register can set only one bit to 1 at the same time. When 1 is written into multiple bits at the same time, writ-
ing in higher order bit is regarded as valid.
D[7:4]
Reserved
D[3:0]
JoinEPdDMA, JoinEPcDMA, JoinEPbDMA, JoinEPaDMA
When this bit is set to 1, the DMA transfer is enabled through the endpoint EP
x
(
x
=a,b,c,d). In addition,
reference to the space capacity (for the IN direction) or the data quantity (for the OUT direction) in the
FIFO of the endpoint EP
x
(
x
=a,b,c,d) by the DMA_Remain H, L register, is enabled.
DMA_Control (DMA Control)
Register name Address
Bit
Name
Setting
Init. R/W
Remarks
DMA_Control
(DMA control)
0x300c92
(8 bits)
D7
DMA_Running
1 DMA is running
0 DMA is not running
0
R
D6
PDREQ
PDREQ signal logic
0
R
D5
PDACK
PDACK signal logic
0
R
D4
–
–
–
–
0 when being read.
D3
CounterClr
1 Clear DMA counter
0 Do nothing
0
W
D2
–
–
–
–
D1
DMA_Stop
1 Finish DMA
0 Do nothing
0
W
D0
DMA_Go
1 Start DMA
0 Do nothing
0
W
This register controls the DMA transfer and shows the status of the interface.
D7
DMA_Running
This bit is automatically set 1 during the DMA transfer. The DMA_Join register cannot be written when
this bit is 1.