28 USB FUNCTION CONTROLLER (USB)
28-44
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
EPbControl (EPb Control)
Register name Address
Bit
Name
Setting
Init. R/W
Remarks
EPbControl
(EPb control)
0x300c41
(8 bits)
D7
AutoForceNAK
1 Auto force NAK
0 Do nothing
0
R/W
D6
EnShortPkt
1 Enable short packet
0 Do nothing
0
R/W
D5
DisAF_NAK_Short
1 Disable auto force
0 Auto force NAK short
0
R/W
D4
ToggleStat
Toggle sequence bit
0
R
D3
ToggleSet
1 Set toggle sequence bit
0 Do nothing
0
W 0 when being read.
D2
ToggleClr
1 Clear toggle sequence bit 0 Do nothing
0
W
D1
ForceNAK
1 Force NAK
0 Do nothing
0
R/W
D0
ForceSTALL
1 Force STALL
0 Do nothing
0
R/W
This register sets operations of the endpoint EPb.
D7
AutoForceNAK
Sets the ForceNAK bit of this register to 1 when the transaction of the endpoint EPb completes normally.
D6
EnShortPkt
Setting this bit to 1 enables to send the data within the FIFO that is less than the quantity specified for
the MaxPacketSize, as a short packet for the IN transaction of the endpoint EPb. When the IN transac-
tion that transmitted short packets completes, this bit is automatically set to 0 (to be cleared). When a
packet of the max packet size is transmitted, this bit is not cleared.
If this bit is set to 1 when the FIFO has no data, a zero-length packet can be transmitted for the IN token
from the host. If the data is written into the FIFO that is in the transmission process with the packet to
which this bit is set, that data may be included in transmission. Therefore, do not write into the FIFO
until the packet transmission completes and this bit is cleared.
D5
DisAF_NAK_Short
When this bit is set to 0 (default setting) and the packet that was received at normal completion time of
the OUT transaction is a short packet, the ForceNAK bit is automatically set to 1. When this bit is set to
1, this function is disabled.
When the AutoForceNAK bit is set to 1, the AutoForceNAK bit has a priority.
D4
ToggleStat
Shows the status of the toggle sequence bit of the endpoint EPb.
D3
ToggleSet
Sets the toggle sequence bit of the endpoint EPb to 1.
D2
ToggleClr
Sets the toggle sequence bit of the endpoint EPb to 0 (to be cleared).
D1
ForceNAK
If this bit is set to 1, the NAK response is done for the transaction of the endpoint EPb regardless of the
FIFO data quantity and space capacity.
When a transaction has been being done for a certain period of time, the setting of this bit will be en-
abled from the next transaction.
D0
ForceSTALL
If this bit is set to 1, the STALL response is done for the transaction of the endpoint EPb. This bit has a
priority over the setting of the ForceNAK bit.
When a transaction has been being done for a certain period of time, the setting of this bit will be en-
abled from the next transaction.
EPcControl (EPc Control)
Register name Address
Bit
Name
Setting
Init. R/W
Remarks
EPcControl
(EPc control)
0x300c42
(8 bits)
D7
AutoForceNAK
1 Auto force NAK
0 Do nothing
0
R/W
D6
EnShortPkt
1 Enable short packet
0 Do nothing
0
R/W
D5
DisAF_NAK_Short
1 Disable auto force
0 Auto force NAK short
0
R/W
D4
ToggleStat
Toggle sequence bit
0
R
D3
ToggleSet
1 Set toggle sequence bit
0 Do nothing
0
W 0 when being read.
D2
ToggleClr
1 Clear toggle sequence bit 0 Do nothing
0
W
D1
ForceNAK
1 Force NAK
0 Do nothing
0
R/W
D0
ForceSTALL
1 Force STALL
0 Do nothing
0
R/W