Basic Stamp 2 voltages

what is the difference between VDD and VIN?

Thanks

Flasher

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  • 7 Comments sorted by Date Added Votes
  • ercoerco Posts: 17,667
    edited March 20 Vote Up0Vote Down
    Vdd is regulated 5.0 volts, which powers the BS2. If you have a clean 5V power supply, you can connect that to Vdd.

    Vin is the input for higher voltages, typically 6-9 volts. The onboard 5V regulator reduces that voltage down to 5.0V for the BS2. That same 5.0V will show up on the Vdd pin, so you may draw a bit of power off that pin to power some external circuitry if you need to.

    Vss is ground, or zero volts, connected to the battery minus terminal.

    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
  • Somewhat loosely defined, (by me, and Wikipedia), Vdd is the term used for CMOS IC positive voltage supply and Vss is the ground connection. Vin is normally referred to the raw, unregulated input power to a regulating device. I always look at Vdd and Vss in electron flow theory as Vss is the source of electrons that flow into the IC and Vdd is the drain where electrons leave the IC.
    Florida, between St. Petersburg and the Gulf of Mexico

    Do not look directly into laser with remaining good eye...
  • ercoerco Posts: 17,667
    Nice description, Hal.

    And then there's Vcc used in some conventions...!
    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
  • Why, thank you, Erco! Looks like we both hit the same Wikipedia page! I guess in some circles it is frowned upon to use a Vcc +5 Volts on a device that wants Vdd +5 Volts, like, "What difference, at this point, does it make?"
    Florida, between St. Petersburg and the Gulf of Mexico

    Do not look directly into laser with remaining good eye...
  • Thank you Hal and Erco. I'm actually trying to figure out the best place to cut into the 9V supply, since my circuit board lacks a switch in that circuit. Why not snip one lead at the battery holder and restore the circuit with a SPST switch?
  • That would certainly give you ON-OFF control, did you have other uses in mind for the Vin - 9 Volt supply?
    Florida, between St. Petersburg and the Gulf of Mexico

    Do not look directly into laser with remaining good eye...
  • Hal,
    I finally finished the in-line switch installation. When I say installation, it sounds like a major endeavor; for me, it was! It was like trying to thread a needle while somebody is shaking your rocker. I didn't know they made nuts and bolts that small.
    Oh-by-the-way, a few years ago, a large department store( Roses) closed in town and I found a bunch of RC cars and bought 7 of them for $5 each. I have had a lot of fun with them, tearing them apart and using the little transceiver to control other projects. The receiver has 13 transistors! I was not able to find out what part of China they were made in.
    73s
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