ISP1362
Single-chip USB OTG controller
Philips Semiconductors
The ISP1362 OTG controller is designed to perform all the tasks specified in the OTG
supplement. It supports Host Negotiation Protocol (HNP) and Session Request
Protocol (SRP) for dual-role devices. The ISP1362 uses software implementation of
HNP and SRP for maximum flexibility. A set of OTG registers provides the control and
status monitoring capabilities to support software HNP or SRP.
Besides the normal USB transceiver, timers and analog components required by
OTG are also integrated on-chip. The analog components include:
• Built-in 3.3 V-to-5 V charge pump
• Voltage comparators
• Pull-up or pull-down resistors on data lines
• Charge or discharge resistors for VBUS
.
11.2 Dual-role device
When port 1 of the ISP1362 is configured in the OTG mode, it can be used as an
OTG dual-role device. A dual-role device is a USB device that can function either as a
host or as a peripheral. As a host, the ISP1362 can support all four types of transfers
(control, bulk, isochronous and interrupt) at full-speed or low-speed. As a peripheral,
the ISP1362 can support two control endpoints and up to 14 configurable endpoints,
which can be programmed to any of the four transfer types.
The default role of the ISP1362 is controlled by the ID pin, which in turn is controlled
by the type of plug connected to the mini-AB receptacle. If ID = LOW (mini-A plug
connected), it becomes an A-device, which is a host by default. If ID = HIGH (mini-B
plug connected), it becomes a B-device, which is a peripheral by default.
Both the A-device and the B-device work on a session base. A session is defined as
the period of time in which devices exchange data. A session starts when VBUS is
driven and ends when VBUS is turned off. Both the A-device and the B-device may
start a session. During a session, the role of the host can be transferred back and
forth between the A-device and the B-device any number of times by using HNP.
If the A-device wants to start a session, it turns on VBUS by enabling the charge pump.
The B-device detects that VBUS has risen above the B_SESS_VLD level and
assumes the role of a peripheral asserting its pull-up resistor on the DP line. The
A-device detects the remote pull-up resistor and assumes the role of a host. Then,
the A-device can communicate with the B-device as long as it wishes. When the
A-device finishes communicating with the B-device, the A-device turns-off VBUS and
both the devices finally go into the idle state. See Figure 18 and Figure 19.
If the B-device wants to start a session, it must initiate SRP by ‘data line pulsing’ and
‘VBUS pulsing’. When the A-device detects any of these SRP events, it turns on its
VBUS (note that only the A-device is allowed to drive VBUS). The B-device assumes
the role of a peripheral, and the A-device assumes the role of a host. The A-device
detects that the B-device can support HNP by getting the OTG descriptor from the
B-device. The A-device will then enable the HNP hand-off by using SetFeature
(b_hnp_enable) and then go into the ‘suspend’ state. The B-device signals claiming
the host role by deasserting its pull-up resistor. The A-device acknowledges by going
into the peripheral state. The B-device then assumes the role of a host and
9397 750 12337
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
Product data
Rev. 03 — 06 January 2004
32 of 150
NXP [ NXP ]
