On Mon, 9 Oct 2017 20:20:07 -0700 (PDT),
fang145...@gmail.com declaimed the
following:
>Hi , I have recently encountered the same problem, another pc is sensbreak,
> I have set the BRKINT flag, and set ttyUSB0 to controlling tty
>successfully, but ttyUSB0's program still didnt receive the SIGINT signal
I'm surprised that any /USB/ serial adapter passes a break signal.
Break, even if handled by a hardware UART (by holding the line down for
some long period), represents a disconnected (broken) serial line
(equivalent to a telephone "flash"/hook switch).
USB itself does not support a physical break. USB<>serial adapters
would have to turn a break into some special command that can be sent over
a USB packet to the adapter, and turned into a hardware break at the
adapter itself -- at which point it may be considered rather futile: the
USB link obviously is not "broken" if packets are being received by the
adapter, so emulating a break would only be on the short span from the
adapter to the board. Similarly, a break from the board to the adapter
would have to be turned into some USB packet and sent to the host driver
which would have to emulate whatever a hardware UART break would cause.
https://electronics.stackexchange.com/questions/51750/does-transmitting-break-over-ftdi-chipset-yield-a-binary-0-received-on-the-recei
seems to say the user was seeing a null byte, and did not see any "framing
error" indication. Again, it could be that the driver on the sending
computer sent a null, but can not send a framing error over USB (remember,
while it looks like a UART to applications, it is just a data byte(s) to
USB packet on the line).
http://www.ftdichip.com/Products/ICs/FT232R.htm
does claim that chip has support for line-break... However, the spec sheet
only uses the word "break" once.
"""
The UART interface also supports the RS232 BREAK setting and detection
conditions.
"""
Doesn't say what it does with them, or how the USB side processes them.
--
Wulfraed Dennis Lee Bieber AF6VN
wlf...@ix.netcom.com HTTP://wlfraed.home.netcom.com/