USB3500 Datasheet, PDF (26/45 Pages) SMSC Corporation – Hi-Speed USB Host, Device or OTG PHY With UTMI+ Interface

USB3500
6.2 OPMODES
The OPMODE[1:0] pins allow control of the operating modes.
TABLE 6-3: OPERATIONAL MODES
Mode[1:0]
00
01
10
11
State Name
Normal Operation
Non-Driving
Disable Bit Stuffing
and NRZI encoding
Reserved
Description
Transceiver operates with normal USB data encoding and decoding
Allows the transceiver logic to support a soft disconnect feature which tri-
states both the HS and FS transmitters, and removes any termination from
the USB making it appear to an upstream port that the device has been
disconnected from the bus
Disables bitstuffing and NRZI encoding logic so that 1's loaded from the DATA
bus become 'J's on the DP/DM and 0's become 'K's
N/A
The OPMODE[1:0] signals are normally changed only when the transmitter and the receiver are quiescent, i.e. when
entering a test mode or for a device initiated resume.
When using OPMODE[1:0] = 10, the SYNC and EOP patterns are not transmitted.
The only exception to this is when OPMODE[1:0] is set to 10 while TXVALID has been asserted (the transceiver is trans-
mitting a packet), in order to flag a transmission error. In this case, the USB3500 has already transmitted the SYNC
pattern so upon negation of TXVALID the EOP must also be transmitted to properly terminate the packet. Changing the
OPMODE[1:0] signals under all other conditions (while the transceiver is transmitting or receiving data) will generate
undefined results.
6.3 Test Mode Support
TABLE 6-4: USB 2.0 TEST MODES
USB 2.0 Test Modes
SE0_NAK
J
K
Test_Packet
Operational Mode
State 0
State 2
State 2
State 0
USB3500 Setup
Link Transmitted Data
No transmit
All '1's
All '0's
Test Packet data
XCVRSELECT &
TERMSELECT
HS
HS
HS
HS
6.4 SE0 Handling
For FS operation, IDLE is a J state on the bus. SE0 is used as part of the EOP or to indicate reset. When asserted in
an EOP, SE0 is never asserted for more than 2 bit times. The assertion of SE0 for more than 2.5us is interpreted as a
reset by the device operating in FS mode.
For HS operation, IDLE is a SE0 state on the bus. SE0 is also used to reset a HS device. A HS device cannot use the
2.5us assertion of SE0 (as defined for FS operation) to indicate reset since the bus is often in this state between packets.
If no bus activity (IDLE) is detected for more than 3ms, a HS device must determine whether the downstream facing
port is signaling a suspend or a reset. The following section details how this determination is made. If a reset is signaled,
the HS device will then initiate the HS Detection Handshake protocol.
DS00002103A-page 26
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