Output level matching?(newbie^^)

Archiver

Does TTL voltage levels and RS-232 polarity output devices can be
connected directly to BS2p? and what exactly different btw. RS-232 in
most book related to BS2 and RS-232 "polarity"? Does it mean true RS-
232?

Archiver

In 'TRUE' RS232, signal levels are +/- 5 volts
to +/- 12 volts. TTL of course is 0 volts to
+5 volts. If you have a 'TRUE' 232 driver, you
need to set up your SEROUT/SERIN baud rates as
'Inverted'.

Now, the Stamp has the ability to RECEIVE 232
with only a 22 Kohm resistor in series with the
RX signal. What happens is the protection diodes
inside the Stamp clip the incoming voltages
(and the 22 KOhm resistor reduces the current)
to the point where no damage occurs, and in fact
you get a 'TTL' signal inside the Stamp.
In this case, you set up your baud rate as
'Normal' (or not Inverted).

If you want to DRIVE 232 out (ie use SEROUT) you'll
need a 'max232' chip, which converts TTL to 232
signal levels. Note you can use 'P16' to talk
out the programming port. You should use 'Inverted'
mode in this case, as the BS2 has a pseudo max232
driver on chip.


--- In basicstamps@yahoogroups.com, "sogilo" <sogilo@y...> wrote:
> Does TTL voltage levels and RS-232 polarity output devices can be
> connected directly to BS2p? and what exactly different btw. RS-232
in
> most book related to BS2 and RS-232 "polarity"? Does it mean true
RS-
> 232?