Logic Probe or Logic pulse?

Archiver

Wat's e diff btw them? I just bought a probe. I think only a probe
can be used to test binary 1 or 0 rite?

BTW, there are 2 switches, TTL or CMOS and PULSE or MEM. Wat r they n
does it make a diff wat I set to?

Thks!

Archiver

A Logic Probe shows you the state of
a digital signal line -- high
(> 1.4 volts == Green) or low (< 0.4 volts
== Red). And yes, it can only test
these binary values. (Although if you
are on an oscillating signal, it can
show you that by the blinking of the
lights)

A Logic Pulser was used in olden days
(1970's) when you had a lot of TTL logic,
and you wanted to 'inject' your own test
signal. You'd touch the probe of the
pulser to an input of the circuit, press
the button, and pulses would go into
your circuit from the Pulser, hopefully
activating other circuitry which you would
monitor with your Logic Probe. It's not
as useful with a Stamp, as the Stamp should
be generating the pulses you want under
your program's control.

Now, the TTL/CMOS switch: It turns out there
are two signaling families, TTL and CMOS. TTL
has a more defined voltage limit (0 to 0.4 volts
is Zero, 1.4 to 5 volts is One, inbetween is undefined).
That's what the lights do in TTL mode.

CMOS has wider allowances for voltage variation,
and that's why you have the CMOS mode. You should
know that while the Stamp is in fact CMOS, it's using
TTL interfaces, so you should use the TTL position.

Pulse/Mem -- If you are trying to find out if there
is a pulse on the line only every so often, you would
put this switch in the 'MEM' position. Then,
monitor the line. When/if the pulse comes through,
you'll see the LED 'latch' -- that is, it will
come on and stay on so you can see it. In the Pulse
position, you'll see the lights flicker if repeated
pulses come through.

Normal operation: TTL, and Pulse.

--- In basicstamps@yahoogroups.com, "barangsg" <barangsg@y...> wrote:
> Wat's e diff btw them? I just bought a probe. I think only a probe
> can be used to test binary 1 or 0 rite?
>
> BTW, there are 2 switches, TTL or CMOS and PULSE or MEM. Wat r they
n
> does it make a diff wat I set to?
>
> Thks!