28 USB FUNCTION CONTROLLER (USB)
28-46
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
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 EPd. 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 EPd.
D3
ToggleSet
Sets the toggle sequence bit of the endpoint EPd to 1.
D2
ToggleClr
Sets the toggle sequence bit of the endpoint EPd 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 EPd 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 EPd. 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.
EPaMaxSize_H (EPa Max Packet Size HIGH)
EPaMaxSize_L (EPa Max Packet Size LOW)
Register name Address
Bit
Name
Setting
Init. R/W
Remarks
EPaMaxSize_H
(EPa max
packet size
high)
0x300c50
(8 bits)
D7–2 –
–
–
–
0 when being read.
D1–0 EPaMaxSize[9:8]
Endpoint EPa max packet size
0x0 R/W
EPaMaxSize_L
(EPa max
packet size
low)
0x300c51
(8 bits)
D7–0 EPaMaxSize[7:0]
Endpoint EPa max packet size
0x0 R/W
EPaMaxSize[9:0]
This register sets the MaxPacketSize of the endpoint EPa.
When using this endpoint for the bulk transfer, 8, 16, 32, or 64 bytes should be set.
When using this endpoint for the interrupt transfer, up to 64 bytes can be set.
If the area of the endpoint EPa is smaller than specified here, the macro does not operate normally.