libftdi Archives

Subject: Re: Problems with FT232R in bitbang mode

From: Thomas Jarosch <thomas.jarosch@xxxxxxxxxxxxx>
To: libftdi@xxxxxxxxxxxxxxxxxxxxxxx
Date: Tue, 18 May 2010 13:50:36 +0200
Helge,

On Friday, 14. May 2010 22:48:07 Helge Lenz wrote:
> So is there any way to make it work with this type of chip or should I
> stop trying and use something else? The one thing that I have not tried
> so far is to put the signal to one of the CBUS lines and use the CBUS
> bitbang mode. So could this be an option to make it work? Or should I
> use the D2XX library for linux instead of libftdi?
> 
> I would really appreciate some hints.

The USB bus doesn't give you a guarantee about the timing, so it might
be too slow to properly modulate a clean carrier signal. There is the
isochronous USB mode which sounds suitable for this kind of application,
though it doesn't handle USB packet loss at all.

Maybe add a small microcontroller to act as a receive buffer and to modulate 
a clean carrier signal? Then you are in control what is happening
with the signal...

Cheers,
Thomas

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