Re: [TCLUG:9791] Palm Pilot and Seral Port

["Eric M. Hopper" <hopper@omnifarious.mn.org>]

On Fri, Nov 05, 1999 at 09:07:28AM -0600, Mike Hicks wrote:
> 
> # cat /proc/tty/driver/serial
> serinfo:1.0 driver:4.27
> 0: uart:16550A port:3F8 irq:4 baud:9600 tx:62939 rx:62927 fe:155 brk:268
> 1: uart:16550A port:2E8 irq:3 baud:9600 tx:13428 rx:13007
> 2: uart:unknown port:3E8 irq:4 
> 3: uart:unknown port:2F8 irq:3
> 
> I understand most of it myself: the chips are 16550As (buffered 16-bit
> serial controller, IIRC), the ports and irqs are normal settings, baud
> is what it should be.  TX and RX would be transmit and receive (what
> they're actually counting is uncertain, though), but what are 'fe' and
> 'brk'?

	I don't know what fe means, but I know what brk means.  brk is a
special RS232C signal often used to indicate some sort of reset.  If you
want a detailed explanation....


	RS232 was initially designed to be completely asynchronous.  In
order to make this work, some sort of signal was needed on the line to
both tell the receiver that bits were coming, and what speed the bits
would be coming at.  Since an RS232 line is normally held 'high', an
initial signal drop indicated that bits were coming.  This is still
reflected in software level RS232 parameters as the 'start bit'.

	A BRK is signalled by an extremely long start bit.

	Gee, I'm almost tempted to try to create ASCII schematics here.
:-)

Have fun (if at all possible),
-- 
Its name is Public Opinion.  It is held in reverence. It settles everything.
Some think it is the voice of God.  Loyalty to petrified opinion never yet
broke a chain or freed a human soul.     ---Mark Twain
-- Eric Hopper (hopper@omnifarious.mn.org
                http://ehopper-host105.dsl.visi.com/~hopper) --

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