ISP1362
Single-chip USB OTG controller
Philips Semiconductors
Table 11: Generic PTD structure: bit description…continued
Name
Status update Description
by HC
Active
Yes
Set to logic 1 by firmware to enable the execution of transactions by the HC.
When the transaction associated with this descriptor is completed, the HC
sets this bit to logic 0 indicating that a transaction for this element should not
be executed when it is next encountered in the schedule.
Toggle
Yes
No
This bit is used to generate or compare the data PID value (DATA0 or DATA1)
for IN and OUT transactions. It is updated after each successful transmission
or reception of a data packet.
MaxPktSize[9:0]
This indicates the maximum number of bytes that can be sent to or received
from the endpoint in a single data packet.
EndpointNumber[3:0]
B3[3] Last (PTD)
No
No
This is the USB address of the endpoint within the function.
This indicates that it is the last PTD of a list. Logic 1 means that this PTD is
the last PTD. The last PTD is used only for ISO. This bit is not used in interrupt
and ATL transfers. The last PTD is indicated by the HcINTLLastPTD and
HcATLLastPTD registers.
Speed (low)
No
This bit indicates the speed of the endpoint.
0 — full-speed
1 — low-speed
TotalBytes[9:0]
No
No
This specifies the total number of bytes to be transferred with this data
structure. This can be greater than MaximumPacketSize.
B5[6] Ping-Pong
0 — This is the ping buffer of the paired buffer. Paired must be logic 1.
1 — This is the pong buffer of the paired buffer. Paired must be logic 1.
B5[7] Paired
No
If this bit is set to logic 1, two PTDs of the same endpoint and address can be
made active at the same time. This bit is used with the Ping-Pong bit. The first
paired PTD always starts with Ping = 0. The pong PTD payload can be sent
out only if the ping PTD payload is sent out. You can also monitor
RAM_BUFFER _STATUS to see which PTD is currently active on the USB
line.
DirToken[1:0]
No
00 — set-up
01 — OUT
10 — IN
11 — reserved
FunctionAddress[6:0]
No
No
This field contains the USB address of the function containing the endpoint
that this PTD refers to.
B7[7:5] PollingRate
B7[4:0] StartingFrame
(interrupt only)
These two fields together select a start frame number (5 bits) and polls the
interrupt device at a rate specified by PollingRate (3 bits); see Section 12.6.
B7[7:0] StartingFrame
(ISO only)
No
The HC compares this byte with the current frame number (can be accessed
from the HcFrameNumber register). The PTD will be processed and sent out
only if the starting frame number equals to the current frame number.
12.5 Features of the control and bulk transfer (aperiodic transfer)
• A Paired PTD is a special feature that provides high performance single endpoint
bulk transfer and handles set-up enumeration sequence within 1 ms. A paired PTD
consists of two PTDs serving the same endpoint of a device that are set active and
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© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
Product data
Rev. 03 — 06 January 2004
44 of 150
NXP [ NXP ]
