isp1512a NXP Semiconductors, isp1512a Datasheet - Page 16

• Manufacturer Part Number: isp1512a
• Description: Ulpi Hi-speed Usb Transceiver
• Manufacturer: NXP Semiconductors

NXP Semiconductors
Table 7.
[1]
Table 8.
ISP1512A_1
Preliminary data sheet
Signal
name
DIR
STP
NXT
Signal
LINESTATE0
LINESTATE1
I = input; O = output; I/O = digital input/output.
ULPI signal description
Signal mapping during low-power mode
Direction on
the ISP1512A
O
I
O
9.2.2 Low-power mode
Maps to
DATA0
DATA1
When the USB bus is idle, the link can place the ISP1512A into low-power mode (also
called suspend mode). In low-power mode, the data bus definition changes to that shown
in
register to logic 0. To exit low-power mode, the link asserts the STP signal. After exiting
low-power mode, the ISP1512A 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 ISP1512A 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
[1]
Signal description
Direction: Controls the direction of data bus DATA[7:0].
In synchronous mode, the ISP1512A drives DIR to LOW by default, making the data bus an
input so the ISP1512A can listen for TXCMD from the link. The ISP1512A 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] are not valid and must be ignored by the link.
DIR is always asserted during low-power and serial modes.
Stop: In synchronous mode, the link drives STP to HIGH for one cycle after the last byte of
data is sent to the ISP1512A. The link can optionally assert STP to force DIR to be
deasserted.
In low-power and serial modes, the link holds STP at HIGH to wake up the ISP1512A,
causing the ULPI bus to return to synchronous mode.
Next: In synchronous mode, the ISP1512A drives NXT to HIGH to throttle data. If DIR is
LOW, the ISP1512A 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 ISP1512A asserts NXT to notify the link that
a valid USB data byte is on DATA[7:0] in the current cycle. The ISP1512A 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 and serial modes.
8. To enter low-power mode, the link sets the SUSPENDM bit in the FUNC_CTRL
Direction
O
O
…continued
[1]
Description
combinatorial LINESTATE0 directly driven by the analog receiver
combinatorial LINESTATE1 directly driven by the analog receiver
Rev. 01 — 31 July 2008
CC
supply; see
ULPI HS USB transceiver
ISP1512A
© NXP B.V. 2008. All rights reserved.
Table
41.
15 of 55