>>    Hi All PICers !
>>
>> Wednesday December 18 1996 15:37,
>> wsci@NET-MAGIC.NET wrote in PICLIST:
>>
>>  w> At 6:06 PM 12/18/96, J. Cabral wrote:
>>  w>
<SNIP>
>
>None of it's necessary. I've always gotten away without any TTL to RS232C
>circuitry, even with a 3V PIC. PC serial ports seem happy to accept
>TTL logic levels, although you have to remember that they're the
>other way up.
>
>Brian Reilly

Brian, don't assume just because one PC Serial Port will work with TTL
Levels that they all will.

I have two different manufacturer's PCs here that both work differently and
both need different levels of negative voltage before they accept an RS-232
"Mark" (1 or negative voltage).

If you're designing for yourself and it works with TTL levels, great.  Just
don't assume that it will work for everybody.

myke

"There are only three kinds of economists in the world.  Those who can count
and those who can't." - Eddy George, governor of the Bank of England