Datasheet

 2014-2016 Microchip Technology Inc. DS00001792E-page 39
USB3320
If an RXCMD event occurs during a USB transmit, the RXCMD is blocked until STP de-asserts at the end of the transmit.
The RXCMD contains the status that is current at the time the RXCMD is sent.
Note 1: An ‘X’ is a do not care and can be either a logic 0 or 1.
2: The value of VbusValid is defined in Table 5-6.
Note 6-1 LineState: These bits in the RXCMD byte reflect the current state of the Full-Speed single ended
receivers. LineState[0] directly reflects the current state of DP. LineState[1] directly reflects the current
state of DM. When DP=DM=0 this is called "Single Ended Zero" (SE0). When DP=DM=1, this is
called "Single Ended One" (SE1).
6.2.4 USB3320 TRANSMITTER
The USB3320 ULPI transmitter fully supports HS, FS, and LS transmit operations. Figure 6-1 shows the high speed, full
speed, and low speed transmitter block controlled by ULPI Protocol Block. Encoding of the USB packet follows the bit-
stuffing and NRZI outlined in the USB 2.0 specification. Many of these functions are re-used between the HS and FS/LS
transmitters. When using the USB3320, Ta bl e 5- 1 should always be used as a guideline on how to configure for various
modes of operation. The transmitter decodes the inputs of XcvrSelect[1:0], TermSelect, OpMode[1:0], DpPulldown, and
DmPulldown to determine what operation is expected. Users must strictly adhere to the modes of operation given in
Table 5-1.
Several important functions for a device and host are designed into the transmitter blocks.
The USB3320 transmitter will transmit a 32-bit long high speed sync before every high speed packet. In full and low
speed modes a 8-bit sync is transmitted.
When the device or host needs to chirp for high speed port negotiation, the OpMode = 10b setting in the Function Con-
trol register will turn off the bit-stuffing and NRZI encoding in the transmitter. At the end of a chirp, the USB3320 OpMode
bits should be changed only after the RXCMD linestate encoding indicates that the transmitter has completed transmit-
ting. Should the opmode be switched to normal bit-stuffing and NRZI encoding before the transmit pipeline is empty, the
remaining data in the pipeline may be transmitted in an bit-stuff encoding format.
Please refer to the ULPI specification for a detailed discussion of USB reset and HS chirp.
TABLE 6-3: ULPI RX CMD ENCODING
Data[7:0] Name Description and Value
[1:0] Linestate UTMI Linestate Signals Note 6-1
[3:2] Encoded
VBUS State
ENCODED VBUS VOLTAGE STATES
VALUE VBUS VOLTAGE SESSEND SESSVLD VBUSVLD
2
00 V
VBUS
< V
SESS_END
100
01 V
SESS_END
< V
VBUS
<
V
SESS_VLD
000
10 V
SESS_VLD
< V
VBUS
<
V
VBUS_VLD
X1 0
11 V
VBUS_VLD
< V
VBUS
XX 1
[5:4] Rx Event
Encoding
ENCODED UTMI EVENT SIGNALS
VALUE RXACTIVE RXERROR HOSTDISCONNECT
00 0 0 0
01 1 0 0
11 1 1 0
10 X X 1
[6] State of ID
pin
Set to the logic state of the ID pin. A logic low indicates an A device. A logic high
indicates a B device.
[7] alt_int Asserted when a non-USB interrupt occurs. This bit is set when an unmasked event
occurs on any bit in the Carkit Interrupt Latch register. The Link must read the Carkit
Interrupt Latch register to determine the source of the interrupt. Section 5.6.1.3
describes how a change on the ID pin can generate an interrupt. Section 6.6 describes
how an interrupt can be generated when the RidConversionDone bit is set.