From: alan@apple.com (Alan Mimms)
Subject: Re: UART needed (really BREAK detect)
Organization: Apple Computer, Inc.
Lines: 26

In article <jam.19.735404158@ameslab.gov>, jam@ameslab.gov (Jerry
Musselman) wrote:
> 
> I need to find a UART that will interface to an 8051 and do the following:
> 	-250k baud, 8 data bits, 2 stop bits, no parity
> 	-ability to do BREAK detect (IRQ or output pin)
> 	-IRQ on character received
> 
> I'm using a Dallas DS2250 at 16 Mhz (8051 clone), but it won't do 
> break detect.  I've looked at the 6850, 8251, 7201, 2661, etc...
> 
> 	Any help would be appriciated!!!

Actually detecting a BREAK is done by watching for a "character" containing
all zero bits with the framing error resulting from its receipt.  This
means that the line stayed in the zero bit state even past the stop bit
time slot, which basically indicates a BREAK.  There is no special way to
detect BREAK that I have found other than this -- there's no magic signal
generated by UARTs, etc.

Alan Mimms (alan@apple.com, ...!apple!alan)   | My opinions are generally
Portable Macintosh Software Group             | pretty worthless, but
Apple Computer                                | they *are* my own...
Art without engineering is dreaming.  Engineering without art is
calculating.
	-- Steven K. Roberts in "Computing Across America"
