need help quickly please
i have a big problem.· I thought that when you don't declare an i/o pin high or low, it disconnects itself from any voltage.· Apparently, current can still flow through my i/o pin even if my program is.
Do
pause 1000
loop
How can I stop current from flowing through the i/o pin.
Do
pause 1000
loop
How can I stop current from flowing through the i/o pin.
Comments
·· You're saying this is the program you downloaded onto the Stamp Module?· Is that everything?· How do you know current is still flowing through the pin?· What's connected to it?
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Chris Savage
Parallax Tech Support
csavage@parallax.com
- The voltage applied to the I/O pin ranges between 0 and 5 V.
- No command that changes the I/O pin from input to output has been used (HIGH and LOW are examples)
Consult the BASIC Stamp Manual to make sure that a given command does not leave an I/O pin in an output state. If you are applying voltages outside the 0 to 5 V range, you will need a series resistor to protect the I/O pin's clamping diodes. For an example of that, see the BASIC Stamp Manual's explanation of SEROUT.
The The BASIC Stamp Manual is available for download from www.parallax.com -> Downloads -> Documentation.
Post Edited (Andy Lindsay (Parallax)) : 6/8/2005 3:57:30 PM GMT
Assuming from some of your other post in the forum that are related to this matter,· I can provide an explanation why you are seeing or
detecting a current flow even if you have declared a Stamp pin as an INPUT.
·
Inside of the IC used on the Stamp, there is what is called a back-to back diode (B2BD)·which is really designed to handle ESD events.
Typically, there is a B2BD circuit on ALL of the IC pins.· When you connect to the BASE of a·PNP transistor through a Stamp I/O, and
the·Emitter of the PNP transistor is connected to a higher voltage potential than the Stamp (5V), you run the risk of this scenario.
·
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.