![](http://datasheet.mmic.net.cn/380000/-PD98501_datasheet_16745028/-PD98501_383.png)
CHAPTER 6 USB CONTROLLER
Preliminary User’s Manual S14767EJ1V0UM00
383
6.2.2.7
USB EP0 Control Register (U_EP0CR): 20H
31
16
MAXP0
15
0
7
6
Reserved
EP0EN
ONAK
NHSK0
OSS
17
18
19
Reserved
30
INAK
ISS
20
21
Register that is used for setting the operation of EndPoint0.
If the value in the MAXP field is rewritten during a send or receive operation, the operation of USB Controller may
become unpredictable. Therefore the MAXP can be written to once only, when initial setting is being performed.
Bit
Field
Description
R/W
31
EP0EN
(EndPoint Enable)
If the V
R
4120A RISC Processor sets this bit to 1, EndPoint0 is enabled for
transmitting and receiving data from and to USB.
R/W
30-19
Reserved
Reserved for future use
R
20
ISS
(IN Send Stall)
If the V
R
4120A RISC Processor sets this bit to 1, STALL packet is sent at
the Data Phase.
If SETUP packet is received when this bit is active, USB Controller clears
this bit to 0.
R/W
19
INAK
(IN NAK)
If the V
R
4120A RISC Processor sets this bit to 1, NAK packet is sent at the
Data Phase.
R/W
18
OSS
(OUT Send Stall)
If the V
R
4120A RISC Processor sets this bit to 1, STALL handshake is
performed at the Handshake Phase.
R/W
17
NHSK0
(No Handshake)
If the V
R
4120A RISC Processor sets this bit to 1, No Handshake is
performed at the Handshake Phase.
R/W
16
ONAK
(OUT NAK)
If the V
R
4120A RISC Processor sets this bit to 1, NAK Handshake is
performed at the Handshake Phase.
If SETUP packet is received when this bit is active, USB Controller clears
this bit to 0.
R/W
15-7
Reserved
Reserved for future use
R
6-0
MAXP0
(MAX Packet size)
Register that stores the Max Packet Size for EndPoint0. Prior to the start of
a USB transaction, the V
R
4120A RISC Controller must write an appropriate
value into this register.
When this field contains 0, no transaction is performed at EndPoint0.
R/W
Remark
When a STALL handshake is sent by a control endpoint in either the Data or Status stage of a control
transfer, a STALL handshake must be returned on all succeeding access to that endpoint until a
SETUP PID is received. The endpoint is not required to return a STALL handshake after it receives a
subsequent SETUP PID. (referred from USB1.1 Specification)