GL800HT25 Datasheet, PDF (15/20 Pages) GENESYS LOGIC – USB 2.0 UTMI Compliant Transceiver IP Core

GL800HT25 USB 2.0 UTMI Compliant Transceiver IP Core
CHAPTER 5 FUNCTIONAL DESCRIPTION
5.1 Transmit Operation
5.1.1 Transmit State Diagram
HRST#
Reset
!TXRDY
!HRST#
!TXVLD
TX Wait
TXVLD
Send SYNC
TX Hold
Reg
Empty
TX Data Load !TXVLD
EOP not
done
Send EOP
TXRDY
TX Hold
Reg Full
TX Data Wait
!TXRDY
TX Hold
Reg
Empty
TX Hold
Reg Full
!TXRDY
Figure 5.1 - Transmit State Diagram
Transmit must be asserted to enable any transmissions.
The SIE asserts TXVLD to begin a transmission.
The SIE negates TXVLD to end a transmission.
After the SIE asserts TXVLD it can assume that the transmission has started when it detects TXRDY
asserted.
The SIE assumes that the UTM has consumed a data byte if TXRDY and TXVLD are asserted.
The SIE must have valid packet information (PID) asserted on the Data bus coincident with the assertion
of TXVLD. Depending on the UTM implementation, TXRDY may be asserted by the Transmit State
Machine as soon as one CLK after the assertion of TXVLD.
TXVLD and TXRDY are sampled on the rising edge of CLK30.
The Transmit State Machine does not automatically generate Packet ID’s (PIDs) or CRC.
When transmitting, the SIE is always expected to present a PID as the first byte of the data stream and if
appropriate, CRC as the last bytes of the data stream.
The SIE must use LINEST0/1 to verify a Bus Idle condition before asserting TXVLD in the TX Wait state.
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