libftdi Archives

Subject: Re: FT2232H asynchronous maximum data rates?

From: Uwe Bonnes <bon@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
To: libftdi@xxxxxxxxxxxxxxxxxxxxxxx
Date: Fri, 17 Jun 2011 22:07:30 +0200
>>>>> "Caleb" == Caleb Kemere <ckemere@xxxxxxxxx> writes:

    Caleb> I've noticed previous threads where folks have used the
    Caleb> synchronous FIFO mode of the FT2232H and gotten quite reasonable
    Caleb> sustained transfer rates (15 MB/s). I'm struggling to get 6.5
    Caleb> MB/s (without the buffer on the chip filling up). Is this an
    Caleb> issue of the asynchronous FIFO mode, or am I somehow not pulling
    Caleb> data off on the PC fast enough?

What direction is the transfer? Device to PC or PC to device? I only have
experience with synchronous read at high rate.  Is your hardware fast
enough? Lookin at the datasheet, I see 80 Nanoseconds needed for each vyte by
the FT232 in FT245 Style Asynchronous FIFO Interface Mode. So if your
hardware adds another 80 ns, you will loose.

Otherwise, how do you read on the PC side? Do yo do asynchronous reads like
in libftdi-1.0/src/ftdi_stream.c?

Bye
-- 
Uwe Bonnes                bon@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Institut fuer Kernphysik  Schlossgartenstrasse 9  64289 Darmstadt
--------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------

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