Hello Ben,
On Friday, 14. August 2009 22:49:05 Ben Plotnick wrote:
> Without configuring the chip at all I see a ~16 ms delay on a read
> command (I assume this is related to the timeout), which is out of spec
> for my application. When I go to lower the chunk size and latency using
> libftdi, I can set it and read it back, but then when I try to switch
> back to VCP mode I get a /dev/ttyUSB0 not found error. I assume that
> libftdi disables the VCP driver or something?
>
> I then cycled the power on the chip and was able to access ttyUSB0 again,
> but the configuration reverted to the defaults. And I am guessing that
> the configuration information is not stored on the EEPROM. So my
> question boils down to this (assuming that I haven't totally misread the
> documentation)...
>
> 1) How would I configure the chip and then proceed to use VCP?
That's exactly the reason why we started libftdi. Back in the days
there was only the ftdi_sio kernel driver (you may call it VCP).
It was very cumbersome to extend for non-standard featurs
like bitbang mode or setting the latency.
libftdi detaches the kernel driver. The latency setting and other values
are configured "per session". I guess the chip reverts
to the default settings once you close the interface.
What about using libftdi instead of VCP for your application?
Cheers,
Thomas
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