🚀 go-pugleaf

In article <9820@etana.tut.fi> nurmi@tut.fi (Nurmi Jari) writes:
>I am looking for a standard serial interface which could be implemented
>using 0-5V CMOS devices...

Well, the Maxim MAX232 family implements real RS232C using a +5 supply,
and as I recall it's a CMOS device...  It has its own voltage multiplier
and inverter to turn +5 into +-9.  This is by far the simplest and least
painful solution unless you have special constraints.  If "using 0-5V
CMOS devices" means "on my own CMOS chip" or "with 4000-series chips only"
or "with very low power consumption", then you do.  Consider RS422, which
is differential (2 wires per signal) but can be done with +5 only if my
memory is correct.  RS423 is sort of a modern RS232 using +-5.  I can't
think of any non-differential +5-only form offhand.

Although the RS232 standard says (-3)-(+3) is the minimum swing, many
RS232 receivers will react acceptably to a 0-3V swing.  That's definitely
non-standard, though.
-- 
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
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