28 USB FUNCTION CONTROLLER (USB)
28-60
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
DMA_Latency (DMA Latency)
Register name Address
Bit
Name
Setting
Init. R/W
Remarks
DMA_Latency
(DMA latency)
0x300c97
(8 bits)
D7–4 –
–
–
–
0 when being read.
D3–0 DMA_Latency[3:0]
Latency
0x0 R/W
This register sets the Data transfer latency for the transfer in the Asynchronous (handshake) mode.
The unit time of the latency is approximately 130 ns.
D[7:4]
Reserved
D[3:0]
DMA_Latency[3:0]
If a value between 0x1 and 0xf is written, the PDREQ signal is negated every time when the 4-word is
transmitted either in the Single Word mode or in the Multi-Word mode, and the PDREQ signal is not be
asserted for (130
×
N) ns period.
DMA_Remain_H (DMA FIFO Remain HIGH)
DMA_Remain_L (DMA FIFO Remain LOW)
Register name Address
Bit
Name
Setting
Init. R/W
Remarks
DMA_Remain_H
(DMA FIFO
remain high)
0x300c98
(8 bits)
D7–4 –
–
–
–
0 when being read.
D3–0 DMA_Remain[11:8]
DMA FIFO remain
0x0
R
DMA_Remain_L
(DMA FIFO
remain low)
0x300c99
(8 bits)
D7–0 DMA_Remain[7:0]
DMA FIFO remain
0x0
R
DMA_Remain[11:0]
When the direction of the endpoint connected to the DMA by the DMA_Join register is the OUT direc-
tion, this register shows the remained data quantity in the FIFO of the endpoint.
When the direction of the endpoint connected to the DMA by the DMA_Join register is the IN direc-
tion, this register shows the space capacity in the FIFO of the endpoint.
The DMA_Remain_H register and the DMA_Remain_L register must be accessed as a pair. When ac-
cessing them, access the DMA_Remain_H register first.
DMA_Count_HH (DMA Transfer Byte Counter HIGH/HIGH)
DMA_Count_HL (DMA Transfer Byte Counter HIGH/LOW)
DMA_Count_LH (DMA Transfer Byte Counter LOW/HIGH)
DMA_Count_LL (DMA Transfer Byte Counter LOW/LOW)
Register name Address
Bit
Name
Setting
Init. R/W
Remarks
DMA_Count_HH
(DMA transfer
byte counter
high/high)
0x300c9c
(8 bits)
D7–0 DMA_Count[31:24]
DMA transfer byte counter
0x0 R/W
DMA_Count_HL
(DMA transfer
byte counter
high/low)
0x300c9d
(8 bits)
D7–0 DMA_Count[23:16]
DMA transfer byte counter
0x0 R/W
DMA_Count_LH
(DMA transfer
byte counter
low/high)
0x300c9e
(8 bits)
D7–0 DMA_Count[15:8]
DMA transfer byte counter
0x0 R/W
DMA_Count_LL
(DMA transfer
byte counter
low/low)
0x300c9f
(8 bits)
D7–0 DMA_Count[7:0]
DMA transfer byte counter
0x0 R/W
DMA_Count[31:0]
These registers specify the data length in the DMA transfer in units of byte, and displays it. Its setting
can be done as large as up to 0xffffffff bytes.