Subject: Re: what is a serial BREAK ?
To: Robert Elz <kre@munnari.OZ.AU>
From: Johnny Billquist <bqt@Update.UU.SE>
List: netbsd-users
Date: 06/02/2005 20:53:14
On Thu, 2 Jun 2005, Robert Elz wrote:

>     Date:        Thu, 2 Jun 2005 12:54:38 +0200 (CEST)
>     From:        Johnny Billquist <bqt@Update.UU.SE>
>     Message-ID:  <Pine.LNX.4.62.0506021249200.4692@Psilocybe.Update.UU.SE>
>   | Once you get a
>   | framing error, and the data is all zeroes, you have detected a break.
> That's a risky assumption - some detection hardware/software distinguishes
> between a framing error that just happens to occur on a nul character,
> and a true break, which is generally required to be a lot longer (perhaps
> 100ms or so).

I don't think there is a specified time for a break character. And older
hardware have no way to differ between a NUL with framing error, and a

But these are nitpicks. If your uart have a special break detection signal
(or status bit), then you probably would use it. If not, then check the
framing error combined with a NUL.


Johnny Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email:           ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol