VCC on SX 48/52 Proto Board

pjv

Hi All;

I'm designing an add-on buffered LED board for the SX 48/52 proto board, and I need to understand the reference to VCC versus VDD on the schematics.

My suspicion is that they are one-and-the-same, and simply inconsitently labeled in the published schematics,·but without a physical unit to inspect, I can't be positive.

Please, can anyone who has such a board confirm that VCC is indeed the same as VDD ?

Many thanks,

Peter (pjv)
·

Chris Savage

Peter,

·· Vcc and Vdd both refer to a circuit's positive power supply rail.· So they would both be the same.· I hope this helps you.

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Chris Savage
Parallax Tech Support
csavage@parallax.com

pjv

Hi Chris;

Thanks for the confirmation.

Cheers,

Peter (pjv)

John Couture

Chris,

Just out of curiosity, is there some "master dictionary" of these symbols?

I understand Vin but where do the Vcc, Vdd, Vss, Vee, etc come from? Schematics don't seem to have a "key" or "legend" like maps do.

Vss, for example is ground. Back in the days before electricity (just kidding) did that mean something like "Short Circuit"?

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John J. Couture

San Diego Miramar College

Chris Savage

John,

·· While I have an extensive electronics background, especially in Digital and Microprocessor technology, I never got any college education in AC electronics, such as you would get at the end of your Engineering degree (the good stuff)...Thusly I have heard several variations on the sources of these symbols.· I have always (Since I was into electonics) known what they mean, but the origins don't seem to be a simply answer even for engineers.· Below is a recent thread with the same question, and some possible answers.

http://forums.parallax.com/showthread.php?p=527322


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Chris Savage
Parallax Tech Support
csavage@parallax.com


Post Edited (Chris Savage (Parallax)) : 9/11/2005 5:24:49 PM GMT

Guenther Daubach

John,

AFAIK, all these names are relics of different digital IC technologies. It all started with the "good old" TTL (Transistor-Transistor Logic) components which used Vcc (V collector-collector) for the positive supply pin and GND (ground) for the negative supply pin. Later, CMOS components came up, and Vdd (V drain-drain) was used for the positive, and Vss (V source-source) for the negative supply pin.

The "official" SX datasheets use the terms Vdd and Vss but you will find different terms in other docs.

The different names for supply pins are sometimes a PIA when you use a PCB layout program, like EGALE where library components can have implied supply pins. This means that such pins by default are not visible with the component's schematic symbols, and the software automatically "connects" such pins to equally-named nets in the schematic (if they are there). Imagine what happens when you want to use one library component with implied names Vcc and GND together with another one with implied Vdd and Vss names. Most likely, the electrical rule check wiull give you an error.

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Greetings from Germany,

G

John Couture

Thank you Guenther, that does help ... I'll add it to a dictionary for the SX Resource pages ... I just noticed that you first name is spelled differently on the cover of your "Programming the SX Microcontroller" book.

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John J. Couture

San Diego Miramar College

LoopyByteloose

Obviously, at times such differences are useful.

But, doesn't the SX-48/52 try to clairfy between the Servo power circuit and the IC only circuit?

You have created some doubts about how I wired my board for servos.

Being an antique myself,
I still prefer +5 regulated [noparse][[/noparse]in this case Vdd], +V unregulated [noparse][[/noparse]in this case Vin], and Ground [noparse][[/noparse]Vss as usual].

[noparse][[/noparse]I may be a bit too generic for some people, but I do teach people how to communicate, English as a 2nd language].
Lingusitically, these systems of jargon are often meant to exclude and confuse the layman as much as help the expert.
For example - Long and short tons, board and cubic feet of lumber. If you don't fully understand them, you may pay more. Maybe a lot more.

So, we will never get rid of the problem - but we can find a way around it

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G. Herzog in Taiwan

Guenther Daubach

John,

you will find various spellings of my first name: Gunther, Guenther, G

Paul Baker

For those of us with American keyboards, there is a short cut to typing extended ASCII codes if you know the decimal number of the ASCII character you want.

Guenther Daubach

Paul,

yes, I did not mention this Alt-Code feature - so here are the "magic numbers" for the Umlauts:

132 -

dkemppai

The different names for supply pins are sometimes a PIA when you use a PCB layout program, like EGALE where library components can have implied supply pins. This means that such pins by default are not visible with the component's schematic symbols, and the software automatically "connects" such pins to equally-named nets in the schematic (if they are there). Imagine what happens when you want to use one library component with implied names Vcc and GND together with another one with implied Vdd and Vss names. Most likely, the electrical rule check wiull give you an error.

Typically, in eagle, you recieve a warning, not an error....·· ...when you connect VDD, VCC, and +5V...· ...there is a little difference between the two. ··· Errors are show stoppers, where warnings are just warnings.

-Dan


P.S. Does anyone know if there is an ASCII way to enter an Omega symbol? (For use in describing circuits?)



Post Edited (dkemppai) : 9/14/2005 3:41:37 PM GMT

Paul Baker

That one is easy to remember, it's 234, Ω

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·1+1=10

Paul

dont forget these:

alt-155 - cents

alt-167 - degrees

alt-171 - 1/2

alt-172 - 1/4

alt-230 - micro << my favorite [noparse];)[/noparse]

alt-241 - +/-

alt-246 - the other divide

alt-249 - the dot

alt-253 - squared

Paul