Akos Vandra wrote:
> Hello!
>
> I am sure you are aware that while most semiconductors' price is
> getting lower and lower, the prices of FT* chips are rising rising.
> I've had enough of this, and intend to write a software clone for the
> FTDI chips using an arm Cortex-M3 or M0 microcontroller.
>
> I would like to ask you if there is a summarized document somewhere of
> the usb transfers that are taking place?
Hi Akos,
I was using the "lpc1343codebase" [1] for a project, and it implements
a USB CDC device, poorly. The Linux cdc-acm driver is a mess, and I
was having problems with a bad interaction causing kernel crashes, so
I made the lpc1343 emulate a FTDI device instead so that I could use
the much more stable ftdi kernel driver.
It's pretty easy to do. Just copy the descriptors, plug it into
Linux, and implement each thing that Linux requests until it works,
using kernel messages and source code to figure out what the right
responses need to be.
This wasn't a full clone of the ftdi by any sense: no bitbang, SPI,
etc. Just enough to act as a serial console for the MCU. I can't
share the code at the moment but I can certainly offer tips if you run
into any problems.
-jim
[1]
http://code.google.com/p/lpc1343codebase/source/browse/#svn%2Ftrunk%2Fcore%2Fusbcdc
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