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Message
From: subha sriraman <sriramanc@y...>
Date: Wed, 29 Oct 2003 10:12:30 -0800 (PST)
Subject: [usb] Packet transfers w USB2.0 core
Hi,
I have a few questions regarding usage of the USB2.0
core for transferring packets (in Host controlled and
DMA modes).
As I understand the USB spec, a device indicates
packet boundaries on bulk pipes by transferring a last
data transaction of less than 64 bytes. If the packet
is an exact multiple of 64 bytes the last data
transaction will have 0 data bytes. Does the USB core
correctly handle this?
1) In Host controlled mode, I assume the packet size
is programmed into the buffer size field to send a
packet (IN)? In this case does the core automatically
generate a 0 byte data transaction at the end if
needed?
2) In DMA mode, the model seems to be a continuous
flow of data bytes (with flow ctl). How does one
indicate packet boundaries?
3) What is the definition of MAX_PL_SIZE? is it
typically 64 bytes (1 transaction)? or is it something
else?
Thanks for your time.
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