STMicroelectronics USB serial controller

[Ian Lepore]

On Tue, 2014-10-14 at 15:06 +0100, Pete French wrote:
> Has anybody got any expereinec with these ? I am
> playing around with a small device (an scrypt ASIC)
> which presents itself to the OS as a serial port, using
> this chipset. When I plug it in I get this:
> 
> ugen0.2: <STMicroelectronics> at usbus0
> umodem0: <STMicroelectronics STM32 Virtual COM Port, class 2/0, rev 2.00/2.00, addr 2> on usbus0
> umodem0: data interface 1, has no CM over data, has no break
> 
> So it thinks it is a USB modem as far as I can make out ?
> I get a /dev/ttyU) device in /dev, but I do not think
> the device should present istelf as a modem. I have
> Linux software which is supposed to talk to
> the chip via a tty, and this does nothing when
> presented with the /dev/ttyU0 device. I also
> cannot get anything out of it.
> 
> I havent dug very far into it yet, but was wondering
> if anyone had any ideas - this is the first time I've seen
> 'umodem' come up.
> 
> cheers,
> 
> -pete.

Try pointing that linux software at /dev/cuaU0 instead of ttyU0.  The
cua devices are "callout" and tty are "dialin" and the distinction is
that the tty layer will block the open of a dialin tty until the modem
carrier-detect is asserted.  Since that isn't a real modem that's
unlikely to happen, but it should always work to open the cua device.

-- Ian