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From: jimc@iscuva.ISCS.COM (Jim Cathey)
Newsgroups: sci.electronics
Subject: Re: Z80-SIO chip programming
Message-ID: <2571@iscuva.ISCS.COM>
Date: 18 Jul 89 15:40:11 GMT
References: <6914@kean.mun.ca>
Organization: ISC Systems Corporation, Spokane WA
Lines: 39

Mail bounced, so here goes...

In article <6914@kean.mun.ca> andrew@kean.mun.ca writes:
>...darn Z80-SIO chip...
>Can _anyone_ please tell me how to set the darn thing to 8 bits, no parity,
>1 stop, and no handshaking (if possible)?

You must program write register 4 first in order to correctly program the SIO.
An OTIR instruction is ideally suited to the purpose of programming SIO's.

To the appropriate command port send:

	$18	; WR0: Channel reset
	$18	; Do it twice in case the part was out-of-sequence.
	$04	; WR0: Select WR4
	$44	; WR4: /16, 1 stop, no parity
	$01	; WR0: Select WR1
	$00	; WR1: No interrupts
	$03	; WR0: Select WR3
	$C1	; WR3: Rx 8 bits, No Auto Enables, Rx Enabled
	$05	; WR0: Select WR5
	$EA	; WR5: Assert DTR, Tx 8 bits, Assert RTS, Tx Enabled.

That should do it.  The SIO kicks the cookies out of most other common serial
chips for flexibility, but without a manual it's a bit hard to use!  Its only
real lack is it has no baud-rate generator.  I would take the SIO over the
265x/266x series, or that nasty 8250, or the 8251/6850 (oldies)...  The DUSCC
is a clear winner, the SCC is just an enhanced SIO, but they did change a few
things that can get you if you're not careful.

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