ISP1362
Single-chip USB OTG controller
Philips Semiconductors
12.3 USB ports
The ISP1362 has two USB ports: port 1 and port 2. Port 1 can be configured as a
downstream port (host), an upstream port (device) or a dual-role port (OTG). Port 2 is
a fixed downstream port.
The function of port 1 depends on two input pins of the ISP1362, namely ID and
OTGMODE.
Table 8:
Port 1 function
OTGMODE
ID
X
Function of port 1
OTG
L
H
H
L
host
H
peripheral
In the OTG mode, port 2 operates as an internal host. It is not advisable to expose
the host port 2 to external devices because it will not respond to the SRP and HNP
protocols. Besides, the current capability of VBUS may be different from the OTG
port’s. The USB compliance checklist states that one and only one USB mini-AB
receptacle is allowed on an OTG device.
12.4 Philips Transfer Descriptor (PTD)
The PTD provides a communication channel between the HCD and the ISP1362
USB HC. A PTD consists of a PTD header and a payload data. The size of the PTD
header is 8 bytes, and it contains information required for data transfer, such as data
packet size, transfer status and transfer token types. Payload data to be transferred
within a particular frame must have a PTD as the header (see Figure 22).
The ISP1362 has three types of PTDs: control and bulk transfer (aperiodic transfer)
PTD, interrupt transfer PTD and isochronous (ISO) transfer PTD.
In the control and bulk transfer PTD and the interrupt transfer PTD, the buffer area is
separated into equal sized blocks that are determined by HcATLBlockSize and
HcINTLBlockSize. For example, if the block size is defined as 32 bytes, the first PTD
structure in the memory buffer will have an offset of 0 bytes and the second PTD
structure will have an offset of 40 bytes [sum of the block size (32 bytes) and the PTD
header size (8 bytes)]. Because of the fixed block size of the ISP1362 HC, however,
even a PTD with 4 bytes of payload will occupy all the 40 bytes in a block.
In the isochronous PTD, the HC uses a more flexible method to calculate the PTD
offset because each PTD can have a different payload size. The actual amount of
space for the payload, however, must be a multiple of DWord. Therefore, a 10-byte
payload must have a reserved data size of 12 bytes. Take for example there are four
PTDs in the ISTL0 buffer area with payload sizes of 200 bytes, 10 bytes, 1023 bytes
and 30 bytes. Then, the offset of each of these PTDs will be as follows:
PTD1 (200 bytes) — offset = 0
PTD2 (10 bytes) — offset = (200 + 8) = 208
PTD3 (1023 bytes) — offset = (200 + 8) + (12 + 8) = 228
PTD4 (30 bytes) — offset = (200 + 8) + (12 + 8) + (1024 + 8) = 1260.
9397 750 12337
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
Product data
Rev. 03 — 06 January 2004
41 of 150
NXP [ NXP ]
