weisen@eniac.seas.upenn.edu (Neil Weisenfeld) (04/12/90)
I need to implement RS-232 communications completely in software. I think
this restriction is being placed on me only to torture me. I am not allowed
to use a UART, I simply need to generate the parity bits, handshaking, etc.
and send them all out to a port (on the 8086).
If anyone knows of a good book on the subject, please e-mail me.
Thanks,
Neil
_____ _____ ------------------------------------
\ / \ / / Neil Weisenfeld
\ / \ / / Computer Science and Engineering
\ / /\ \ / / Unviersity of Pennsylvania
\ / / \ \ / / --------------------------------------
\ / / \ \/ / InterNet: weisen@eniac.seas.upenn.edu
\ / / \ / USPS: 3700 Spruce St. Box 572
\/____/ \_____/ Philadelphia, PA 19104
--------------------------------------fyl@ssc.UUCP (Phil Hughes) (04/14/90)
In article <23126@netnews.upenn.edu>, weisen@eniac.seas.upenn.edu (Neil Weisenfeld) writes: > I need to implement RS-232 communications completely in software. I think > this restriction is being placed on me only to torture me. I am not allowed > to use a UART, I simply need to generate the parity bits, handshaking, etc. > and send them all out to a port (on the 8086). I don't know what sort of port you are going to talk to but RS-232 specifies a lot of characteristics of an electrical interface. For example, the voltage levels are between +5 and +25V for a space and between -5 and -25V for a mark condition on the line. Also, there are limits on the rise time (25V/microsecond maximum slew rate). So, you need some sort of hardware that can deal with this. As far as assembling the bits, it is start bit first, LSB, ..., MSB, parity, stop bit. > If anyone knows of a good book on the subject, please e-mail me. We (SSC) is just finishing up a card on RS-232. It will tell you what the signals are, what pins they go on, where the bits goes and such. It won't tell you how to get +25V and -25V out of a TTL port however. Good luck. -- Phil Hughes, SSC, Inc. P.O. Box 55549, Seattle, WA 98155 (206)FOR-UNIX uunet!pilchuck!ssc!fyl or attmail!ssc!fyl (206)527-3385