Datasheet
8.2OPMODESThe OPMODE[1:0] pins allow control of the operating modes.
Table 8.2 Operational Modes
MODE[1:0] | STATE# | STATE NAME | DESCRIPTION |
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00 | 0 | Normal Operation | Transceiver operates with normal USB data encoding and |
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| decoding |
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01 | 1 | Allows the transceiver logic to support a soft disconnect feature | |
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| which |
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| any termination from the USB making it appear to an upstream |
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| port that the device has been disconnected from the bus |
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10 | 2 | Disable Bit Stuffing | Disables bitstuffing and NRZI encoding logic so that 1's loaded |
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| and NRZI encoding | from the DATA bus become 'J's on the DP/DM and 0's become |
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| 'K's |
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11 | 3 | Reserved | N/A |
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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 (state 2), OPMODES are set, and then 5 60MHz clocks later, TXVALID is asserted. In this case, the SYNC and EOP patterns are not transmitted.
The only exception to this is when OPMODE[1:0] is set to state 2 while TXVALID has been asserted (the transceiver is transmitting a packet), in order to flag a transmission error. In this case, the USB3280 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.
Under no circumstances should the device controller change OPMODE while the DP/DM lines are still transmitting or unpredictable changes on DP/DM are likely to occur. The same applies for TERMSELECT and XCVRSELECT.
8.3Test Mode SupportTable 8.3 USB 2.0 Test Modes
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| USB3280 SETUP |
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| XCVRSELECT & |
USB 2.0 TEST MODES | OPERATIONAL MODE | SIE TRANSMITTED DATA | TERMSELECT |
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SE0_NAK | State 0 | No transmit | HS |
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J | State 2 | All '1's | HS |
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K | State 2 | All '0's | HS |
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Test_Packet | State 0 | Test Packet data | HS |
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SMSC USB3280 | 29 | Revision 1.5 |
| DATASHEET |
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