Re: [Ftdi-usb-sio-devel] Extending the ftdi_sio driver for RS-485 usage with the FT4232H

[Bill R. <bil...@gm...>]

Hi there,

The driver does not set the pin direction of any channel. It doesn't
need to for RS232 mode.

And the interface the driver implements was never designed to talk
that protocol.

You will need to ask ftdi to tell you how to do that.

Also libftdi is definitely your best bet because it can talk directly
to the chip how ever you like.

http://www.intra2net.com/en/developer/libftdi/links.php


On Sat, Jul 7, 2012 at 7:29 AM, Matt Barclay <mba...@gm...> wrote:
> Hello,
>
> Looking for some help understanding the ftdi_sio driver.  I've used the
> libftdi interface to this chip before and I'm not seeing many parallels in
> the Kernel driver.
>
> In the RS-485 configuration for the FT4232H, bit7 of the channel is used as
> an output for TXD Enable.  In UART mode (the default used by ftdi_sio), this
> is the input signal RI# (Ring Indicator).
>
> Where does the ftdi_sio.c driver set the pin direction for the channel?  I
> need to re-purpose this pin to be an input, and drive it high during TX
> operations.
>
> For reference, page 12 describes pin usage, page 19 describes RS-485
> configuration:
>
> http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT4232H.pdf
>
> Thanks,
> Matt
>
>
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