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Message
From: Matt Gillespie<matt.gillespie@j...>
Date: Wed Jan 26 12:34:25 CET 2005
Subject: [usb] Bulk in not NAKing in usb1_funct
I have been having a problem with ReadFile if I set nNumberOfBytesToRead
greater than the packet size. The usb developers forum had suggested that
the IN packet from the host was not being NAK’ed correctly and with a
modified testbench I found this to be true. My problem is that the buffer
returned from ReadFile correctly return the amount of data received at the
point at which the function is called but the data is scattered around the
buffer in Maxpacket sized blocks.
Looking back through previous posts I believe that the bulk in was never
designed to NAK even though it is required by the spec usb rev2. 8.4.6.1. I
believe that the original application was a streaming audio app.
I have added some bulk in and out tests to my testbench and changing line
665 of usb1_pe from
if(txfr_int & ep_empty)
to
if(txfr_bulk & ep_empty & !ctrl_ep)
and corrected the sensitivity list. I am not using interrupt transfers so
that doesn’t affect me. Does anyone see any problems with this or have a
better way of doing it?
This does not get around the requirement to double buffer the data if you do
not receive an ACK from the host. This is a separate issue.
Matt Gillespie
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