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Hi I am using an Arduino Uno on Windowss 7 and this is my first time compiling.

I've written code for a BCH that I can post if needed.
My problem that I'm having is after I upload and read the signals from the arduino (via multimeter),
i get readings between -.03 (LOW) and -3.6 (HIGH)

I'm not understanding why I am getting negative readings.

I have all 7 inputs wired properly, but just the 7 inputs.
Is there more that I need to wire in?

Any help would be super greatly appreciated
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I don't think you connected the grounds, Dave.
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I'm not understanding why I am getting negative readings.
Because you've got the meter leads the wrong way around?
Or with the wrong ground reference?

What's a "BCH"?
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Binary coded hex,

i don't think it has to do with my leads
if it was my leads and it was outputting properly then I would expect the 7 segment display to come on
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i get readings between -.03 (LOW) and -3.6 (HIGH)
So if you haven't connected the leads up wrong then you have invented a new way to generate negative voltages from a positive supply.

You simply can't get negative voltages out of an arduino output, period.

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if it was my leads and it was outputting properly then I would expect the 7 segment display to come on
You might expect it but the fact that it is not happening points to some error you have made.

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Binary coded hex,
In over 40 years of playing with this stuff I have never come across this term, it simply does not make sense.
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thanks for not being helpful at all

if anyone at all would like to be helpful and actually try to understand what I'm doing I would appreciate that a lot.
i can post code if anyone would care to take a look at it, but I don't know where the source of the problem is.

For anyone else that wants to post and criticize me on how I don't know what I'm doing, I'll stop you right now and tell you that this is my first time working with arduino.
So i don't know what I am doing.
that being said if anyone has come across or seen a problem similar to this and they have a solution, please share with me and help me get further in my project.

As to why I'm getting a negative reading I don't know.
My black lead is touching GND that is coming from my 5V power supply, which is connected to my breadboard.
The red lead is touching the output pins of the arduino, and giving me negative voltages.
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Because you've got the meter leads the wrong way around?
Or with the wrong ground reference?

I am using a different ground reference, that being said I didn't know that LOW volatage of one power supply meant high voltage to another.
So I guess than the problem is that I don't know where to receive a GND signal from the arduino.
And I also don't understand how, if the arduino is sending power to my LEDs, why aren't they lighting up at all.
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thanks for not being helpful at all
Your welcome, thanks for responding so well. When some one comes on and states something impossible is happening and then refuses to believe he is making an error, then a certain amount of micky taking is to be expect. You are making an error or your meter is bust. Do you have the red and black wires connected to the V and Com inputs of the meter. Com = black.

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My black lead is touching GND that is coming from my 5V power supply, which is connected to my breadboard.
The red lead is touching the output pins of the arduino, and giving me negative voltages.

So at last you are giving us something to go on, some detail that might reveal what you are doing wrong.
Have you tried measuring the voltage coming from your 5V power supply, by just moving one lead from the arduino output to the 5V power supply output. Is it still negative or has it dropped to zero? Have you tried swapping the red and black wires over, does it now read a positive value.

Where are you connecting the 5V power supply to? Connecting it to the wrong point might give you only a 3.6V logic high output. If it is a regulated 5V it should be connected to the 5V pin NOT the Vin pin. Only use the Vin pin for voltages over 7V, this feeds the regulator that cuts it down to 5V.

A schematic of what you are wiring up would be great.
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So I guess than the problem is that I don't know where to receive a GND signal from the arduino.
It is from the socket pin labeled GND, it should be the same place where your power supply is connected to.

All grounds must be common.

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that being said I didn't know that LOW volatage of one power supply meant high voltage to another.
Voltage is a measure of potential DIFFERENCE that is the diffrence in potential between two points, not the potential of one point.
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one thing that should be noted is the power supply isn't connected to the arduino, i was told by my friend that it wasn't needed.

The only thing connected to the arduino is my 7 output wires.

the 5V power supply is connected to my breadboard which is providing a GND for the 7-seg display.
I suppose this is where I am going wrong.

Should I connect the GND of the 7-seg to the arduino instead of a separate power supply?

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When some one comes on and states something impossible is happening and then refuses to believe he is making an error, then a certain amount of micky taking is to be expect.

I apologize for being abrasive, and i appreciate you helping me
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one thing that should be noted is the power supply isn't connected to the arduino, i was told by my friend that it wasn't needed.

It would be tons better if you could post a wiring diagram of your setup, but I suspect your friend might be mistaken.
The only thing connected to the arduino is my 7 output wires.

Then how is the arduino getting powered?

the 5V power supply is connected to my breadboard which is providing a GND for the 7-seg display.
I suppose this is where I am going wrong.

Should I connect the GND of the 7-seg to the arduino instead of a separate power supply?

Again a wiring diagram would confirm the need, but for most situations the arduino ground must be wired to your external power supply's negative terminal as well as to any 7-seg display ground connections.
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When some one comes on and states something impossible is happening and then refuses to believe he is making an error, then a certain amount of micky taking is to be expect.

That is because you didn't post a wiring diagram, so answers are assuming that external wiring was done correctly, which in your case may not be correct. But the statement that an arduino can not output a negative voltage relative to it's ground pin is a fact.

I apologize for being abrasive, and i appreciate you helping me

Again you can help us best help you by posting a wiring diagram.

The basic rule is if asking about software problem you should post your code. If asking about hardware problems you should post your wiring diagram. If your not sure where the problem might be post both.

Lefty
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Then how is the arduino getting powered?

The arduino's being powered by the computer I'm plugging it into.

I honestly don't know how I would draw a wiring diagram with a reference to an arduino.

I don't completely understand the interface of the arduino enough to understand what is what
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If your power supply is not connected to the arduino on the +5V then there is no need to connect the ground of it to your circuit.
The LEDs in your circuit should be connected to the output pin, then to a resistor then to the arduino ground.
Then they will light up when you put the output high.
If you can't draw a schematic then take a photo.
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the problem is fixed, i just had to connect GND and +5V on the arduino to my power supply.

such a small problem and I feel like a fool and a jackass for making this difficult for you guys trying to help me.
I'm sorry for that and I appreciate you helping me get this problem straight
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I don't think you connected the grounds, Dave.
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Thanks for sticking with it.
It simply isn't possible to judge experience from a post count, so questions may be pitched high at first.
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i just had to connect GND and +5V on the arduino to my power supply.
It is not a good idea to connect the 5V on your power supply to the 5V on the arduino when the 5V is being provided by the USB socket. This is because if the power supply is higher than the USB voltage it will push current up the USB line and upset it. If it is lower then the USB current will be pushed into the power supply.
The old arduinos used to have a link that would select where the power came from. This is not on the modern boards. You might want to have a special USB lead that has a break in the +5V line.
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