isp1508a NXP Semiconductors, isp1508a Datasheet - Page 40

• Manufacturer Part Number: isp1508a
• Description: Isp1508a; Isp1508b Ulpi Hi-speed Universal Serial Bus Transceiver
• Manufacturer: NXP Semiconductors

NXP Semiconductors
ISP1508A_ISP1508B_1
Product data sheet
10.7.1 Full-speed or low-speed host-initiated suspend and resume
10.7 USB suspend and resume
Figure 18
suspend and sometime later initiates resume signaling to wake-up the downstream
peripheral. Note that
LINESTATE updates.
The sequence of events for a host and a peripheral, both with ISP1508, is as follows:
1. Idle: Initially, the host and the peripheral are idle. The host has its 15 k pull-down
2. Suspend: When the peripheral sees no bus activity for 3 ms, it enters the suspend
3. Resume K: When the host wants to wake up the peripheral, it sets OPMODE[1:0] to
4. EOP: When STP is asserted, the ISP1508 on the host side automatically appends an
Fig 17. Preamble sequence
DATA[7:0]
resistors enabled (DP_PULLDOWN and DM_PULLDOWN are set to 1b) and 45
terminations disabled (TERMSELECT is set to 1b). The peripheral has the 1.5 k
pull-up resistor connected to DP for full-speed or DM for low-speed (TERMSELECT is
set to 1b).
state. The peripheral link places the PHY into low-power mode by setting the
SUSPENDM bit in the Function Control register, causing the PHY to draw only
suspend current. The host may or may not be powered down.
10b and transmits a K for at least 20 ms. The peripheral link sees the resume K on
LINESTATE, and asserts STP to wake up the PHY.
EOP of two bits of SE0 at low-speed bit rate followed by one bit of J. The ISP1508 on
the host side knows to add the EOP because DP_PULLDOWN and DM_PULLDOWN
are set to 1b for a host. After the EOP is completed, the host link sets OPMODE[1:0]
to 00b for normal operation. The peripheral link sees the EOP and also resumes
normal operation.
DP or DM
CLOCK
NXT
STP
DIR
DP and DM timing is not to scale.
illustrates how a host or a hub places a full-speed or low-speed peripheral into
Figure 18
Rev. 01 — 14 August 2007
FS SYNC
TXCMD (low-speed packet ID)
timing is not to scale, and does not show all RXCMD
PRE ID
FS
IDLE (min
4 FS bits)
ISP1508A; ISP1508B
LS SYNC
D0
LS PID
ULPI HS USB transceiver
D1
LS D0
© NXP B.V. 2007. All rights reserved.
LS D1
004aaa714
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