Re: Unidentified subject!
- To: MISC
- Subject: Re: Unidentified subject!
- From: Frank Sergeant <FS07675@xxxxxxx>
- Date: Wed, 28 Dec 1994 01:02:28 -0600 (CST)
- Organization: Southwest Texas State University
Tuesday, December 27, 1994
>>
>>Does this mean, that no 12V-5V converters are required? Can I just
>>connect IN0 to TD, OUT0 to RD, and Gnd to SG?
>Yes. I have done it directly on several computers. I tried it
>But it appears PCs (8088-486) machines that I use have
>no problem with 0-6V on a serial line.
I, too, have had good success using 0 and 5 volt levels to connect
to the serial port of PCs (zero volts in place of the -3 to -15 the
PC expects; 5 volts in place of the +3 to +15 the PC expects). When
running from the serial port of a 68HC11, I typically run each signal
through a CMOS inverter (74HC4049, for example). If you have direct
software control of the bits, you can do the inversion in software.
I do use current limiting resistors, just on "general principles."
I was bit, once, on this with some old serial cards that insisted
on a negative voltage and just would not accept zero volts. I've
never had any trouble on newer machines, as far as I know. Besides,
I hate to spend the power the MAX232 chip requires.
-- Frank
Frank Sergeant
fs07675@academia.swt.edu