What's really going on here?

Dr.No

I'm using a BS2 to test when a circuit is active by connecting the main (5V+) to a pin
using a 220 resistor.

I measured the volt after the load and it is less than 1 volt. If I connect this to the pin, it
is still able to detect the volt (LED lights up).

However, if I run the circuit on 1.3 Volts, the stamp doesn't pick this up.

The only thing I can think of is the load is still spitting out 5V, but it's probably so
low it's not measurable - but detectable.

Mike Green

You're not likely to get an answer without posting a circuit diagram. The Stamp I/O pin in input mode is a high impedance gate input. The BS2 is made with a PIC16F57. With a +5V supply voltage for the processor, the input threshold is 0.8V to 2.0V at room temperature. The lower end is guaranteed to be a logic zero and the upper end is guaranteed to be a logic one. The middle is roughly 1.4V. If your circuit is behaving differently, there's probably something about your circuit that's not behaving the way you expect. Without a schematic, all we can do is guess.

Dr.No

Thank.

Is there a IC or anything that can drop the volts by say 1 or 2 volts?
I dont need a volt regulator because I'm not trying to regulate or get a fixed volt,
I only want to lower the given volt a little to test the pin.

Thanks.

metron9

You can drop .7 volts with a typical diode, two of them in series would be about 1.4V . Connect your circuit to the output of the diodes and your pin and 220 ohm resistor to the input of the diode.


5V> -diode-diode->3.6V output to circuit
|_-resistor22ohm--->(Stamp pin)

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Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
Think outside the BOX!

Chris Savage

Without a schematic there would be little most of us could offer. I am not clear on your connections by your description. It sounds like there is a load device and an LED, but it’s not clear where or how they’re connected and if the connections are related to the pin with the 220 ohm resistor.

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Chris Savage
Parallax Tech Support

Chris Savage

It seems this may be a duplicate post from the following thread. Please answer only in the original thread linked below.

http://forums.parallax.com/showthread.php?p=739907

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Chris Savage
Parallax Tech Support

Dr.No

The first post Testing A Circut was figuring out...

(1) why I could NOT get the stamp to detect an input pin,
(2) why the LED kept blinking

My question was...
Everything works except I'm not picking up any 1s on the IN1 except 0s.
If anyone can give an help, I would greatly appreciate it.

Second Post What's Really Going On Here:
A far cry for help in figuring out the anomolies regarding volts, current and why the pin can
actually detect <1.0 volts and why it it can't detect 1.3volts.
And second, finding a volt reducer IC or component.

The reason the two post may sound familar is I have to post background info so readers
can know what I'm doing and the circumstances surrounding my questions.

I was always told, be clear and percise so as not to confuse readers who in return will have
more question than answers, and asking new question on a old post
may be ignored, so use new posts for new questions on new topics.

Thank you for your time.

Chris Savage

Dr. No,

You’re defending what looks to me like a double post in that you’re repeating yourself for clarity, but you never provided the information asked for by those replying to this thread in order to help you.

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Chris Savage
Parallax Tech Support