Re: New approach to transfer exact data By FT2232H
- From: Paul Carpenter <paul@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Tue, 16 Jun 2009 22:40:57 +0100
In article <b519f58f-bdcd-4a19-b644-
f4d34a1a22d9@xxxxxxxxxxxxxxxxxxxxxxxxxxx>, alex.louie@xxxxxxxxx says...
On Jun 16, 6:14 am, Paul Carpenter <p...@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
wrote:
Windows CANNOT guarantee a timed capture of high speed data, and gets
worse the larger the dataset size.
The USB protocol is supposed to allow large transfers without data
corruption.
Often assumes that the data is coming from something like a hard drive
where pauses can be coped with. NO USB driver can buffer 10's or 100's MB
of continuous data stream in a GUARANTEED manner on ANY windows platform,
because the system is busy with another task, or some other driver like
CDROM or graphics is hogging the system.
Timed capture of continuous data streams cannot be guaranteed on ANY
windows platform, with ANY driver. Not without sufficient external
buffering which also has to be large to cope with ALL situations.
I will not argue that Windows has a lot of room for improvement, but
USB transfers of gigabytes of data at megabytes per second can be done
accurately if the driver is written properly.
It is more likely to be achievable with better drivers, but guaranteeing
continuous data streams (timed capture) without external buffering on
ANY windows system is impossible.
And I do know that the FTDI drivers are not written properly.
I know and any correspondence/contact them is met with disbelief
that anything is wrong at all. They seem to believe everybody has
the exact same setup as they have, even their customers' customers.
At best FTDI is good for small data sets on non-continuous data
streams, that can be paused.
AL
--
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- References:
- New approach to transfer exact data By FT2232H
- From: Paul Ham
- Re: New approach to transfer exact data By FT2232H
- From: Paul Carpenter
- Re: New approach to transfer exact data By FT2232H
- From: LittleAlex
- New approach to transfer exact data By FT2232H
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