isp1705 NXP Semiconductors, isp1705 Datasheet - Page 25

• Manufacturer Part Number: isp1705
• Description: Ulpi Hi-speed Usb Transceiver
• Manufacturer: NXP Semiconductors

NXP Semiconductors
Table 10.
[1]
ISP1705_1
Product data sheet
Signal name
DIR
STP
NXT
I = input; O = output.
ULPI signal description
9.2.2 Low-power mode
Direction on
the ISP1705
O
I
O
When the USB bus is idle, the link can place the ISP1705 into low-power mode (also
called suspend mode). In low-power mode, the data bus definition changes to that shown
in
FUNC_CTRL register (see
asserts the STP signal. After exiting low-power mode, the ISP1705 will send an RXCMD
to the link if a change was detected in any interrupt source, and the change still exists. An
RXCMD may not be sent if the interrupt condition is removed before exiting.
The ISP1705 will draw only suspend current from the V
During low-power mode, the clock on XTAL1 may be stopped. The clock must be started
again before asserting STP to exit low-power mode.
For more information on low-power mode enter and exit protocols, refer to UTMI+ Low Pin
Interface (ULPI) Specification Rev. 1.1 .
Table 11.
Signal
LINESTATE0
LINESTATE1
Table
[1]
Signal description
Direction: Controls the direction of data bus DATA[7:0].
In synchronous mode, the ISP1705 drives DIR to LOW by default, making the data bus an
input so the ISP1705 can listen for TXCMD from the link. The ISP1705 drives DIR to
HIGH only when it has data for the link. When DIR and NXT are HIGH, the byte on the
data bus contains decoded USB data. When DIR is HIGH and NXT is LOW, the byte
contains status information called an RXCMD (receive command). The only exception to
this rule is when the PHY returns register read data, where NXT is also LOW, replacing
the usual RXCMD byte. Every change in DIR causes a turnaround cycle on the data bus,
during which DATA[7:0] is not valid and must be ignored by the link.
DIR is always asserted during low-power, serial and UART modes.
Stop: In synchronous mode, the link drives STP to HIGH for one cycle after the last byte
of data is sent to the ISP1705. The link can optionally assert STP to force DIR to be
deasserted.
In low-power, serial and UART modes, the link holds STP at HIGH to wake up the
ISP1705, causing the ULPI bus to return to synchronous mode.
Next: In synchronous mode, the ISP1705 drives NXT to HIGH to throttle data. If DIR is
LOW, the ISP1705 asserts NXT to notify the link to place the next data byte on DATA[7:0]
in the following clock cycle. If DIR is HIGH, the ISP1705 asserts NXT to notify the link that
a valid USB data byte is on DATA[7:0] in the current cycle. The ISP1705 always drives an
RXCMD when DIR is HIGH and NXT is LOW, unless register read data is to be returned
to the link in the current cycle.
NXT is not used in low-power, serial and UART modes.
11. To enter low-power mode, the link sets the SUSPENDM bit in the
Signal mapping during low-power mode
…continued
Maps to
DATA0
DATA1
Rev. 01 — 13 June 2008
Section
Direction
O
O
11.5) to logic 0. To exit low-power mode, the link
[1]
Description
combinatorial LINESTATE0 directly driven by
the analog receiver
combinatorial LINESTATE1 directly driven by
the analog receiver
CC
ULPI Hi-Speed USB transceiver
supply; see
Table
© NXP B.V. 2008. All rights reserved.
ISP1705
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