28 USB FUNCTION CONTROLLER (USB)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
28-55
When a bit of the CPU_JoinRd register is set to 1, the data can be read from the FIFO by reading values
from this register.
When a bit of the CPU_JoinWr register is set to 1, the data can be written into the FIFO by writing val-
ues into this register.
If values are read from this register without setting the EnEPnFIFO_Rd bit of the EnEPnFIFO_Access
register, a dummy data will be output.
If writing is done into this register without setting the EnEPnFIFO_Wr bit of the EnEPnFIFO_Access
register, writing into the FIFO is not done.
If this register is read when the FIFO of the relevant endpoint is empty, a dummy data will be read.
If writing is done into this register when the FIFO of the relevant endpoint has no space, writing into
the FIFO is not done.
EPnRdRemain_H (EPn FIFO Read Remain HIGH)
EPnRdRemain_L (EPn FIFO Read Remain LOW)
Register name Address
Bit
Name
Setting
Init. R/W
Remarks
EPnRdRemain
_H
(EPn FIFO read
remain high)
0x300c84
(8 bits)
D7–4 –
–
–
–
0 when being read.
D3–0 EPnRdRemain[11:8]
Endpoint n FIFO read remain
0x0
R
EPnRdRemain
_L
(EPn FIFO read
remain low)
0x300c85
(8 bits)
D7–0 EPnRdRemain[7:0]
Endpoint n FIFO read remain
0x0
R
EPnRdRemain[11:0]
This register shows the remained data quantity in the FIFO of the endpoint connected to the CPU
Interface by the CPU_JoinRd register. When the remained data quantity in the FIFO is acquired, the
EPnRdRemain_H and the EPnRdRemain_L registers must be accessed as a pair. When accessing them,
access the EPnRdRemain_H register first.
EPnWrRemain_H (EPn FIFO Write Remain HIGH)
EPnWrRemain_L (EPn FIFO Write Remain LOW)
Register name Address
Bit
Name
Setting
Init. R/W
Remarks
EPnWrRemain
_H
(EPn FIFO write
remain high)
0x300c86
(8 bits)
D7–4 –
–
–
–
0 when being read.
D3–0 EPnWrRemain[11:8]
Endpoint n FIFO write remain
0x0
R
EPnWrRemain
_L
(EPn FIFO write
remain low)
0x300c87
(8 bits)
D7–0 EPnWrRemain[7:0]
Endpoint n FIFO write remain
0x0
R
EPnWrRemain[11:0]
This register shows the space capacity in the FIFO of the endpoint connected to the CPU Interface by
the CPU_JoinWr register. When the space capacity in the FIFO is acquired, the EPnWrRemain_H and
the EPnWrRemain_L registers must be accessed as a pair. When accessing them, access the EPnWrRe-
main_H register first.
DescAdrs_H (Descriptor Address HIGH)
DescAdrs_L (Descriptor Address LOW)
Register name Address
Bit
Name
Setting
Init. R/W
Remarks
DescAdrs_H
(Descriptor
address high)
0x300c88
(8 bits)
D7–4 –
–
–
–
0 when being read.
D3–0 DescAdrs[11:8]
Descriptor address
0x0 R/W
DescAdrs_L
(Descriptor
address low)
0x300c89
(8 bits)
D7–0 DescAdrs[7:0]
Descriptor address
0x0 R/W