libftdi Archives

Subject: Re: Use of ftdi-sio and libftdi on different interfaces of the same instance of FT4232 (and similar)

From: Uwe Bonnes <bon@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
To: libftdi@xxxxxxxxxxxxxxxxxxxxxxx
Date: Thu, 30 Sep 2010 12:30:54 +0200
>>>>> "Ales" == Ales Teska <ales.teska@xxxxxxxxx> writes:

    Ales> Hi, I'm working on a project that make use of FT4232 chip. The
    Ales> design says that some of the FT4242 ports will be connected to
    Ales> things like GSM modem and GPS devices and some will be using MPSSE
    Ales> for bit banging purposes. Whole thing is running on the Linux with
    Ales> quite decent Linux kernel (2.6.34).

    Ales> Now problem is that obviously it is not possible today to
    Ales> configure ftdi-sio a libftdi to share same USB device. Right?  I
    Ales> assume that if ftdi-sio 'locks' USB device, then it is not
    Ales> possible to speak with that thru libusb/libftdi.

    Ales> We will probably lucky enough with our project as we have 2 FT4232
    Ales> chips and we can reshuffle design to move read RS232 connections
    Ales> to one chip and other use for bit banging. But is the a way or a
    Ales> plan to change this? It is possible to split device use this way
    Ales> on Windows and with vendor D2XX library (on Linux they have the
    Ales> same issue).

If you open the USB interface with libftdi, the kernel mode driver is detached
from the interface. Reattaching is another thing, but is doable.
If you need nearly concurrent access to the UART/MPSSE, write the whole
application as a libftdi application, handling UART inside libftdi too.

Uwe Bonnes                bon@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

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

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