Hello guys,
I am a newbie to arduino world and just bought a starter kit of arduino uno 3 days ago, so sorry if my question may sound stupid . Firstly, I started from the Starter Guide that came along with it. After understanding quite a few concepts, a doubt came into my mind and its this:
In a small circuit explaining about Digital Output where we program a simple led to make the LED on and off for 1 second each; What is the function of connecting the 5V pin of the uno board to the +ive rail of the breadboard? Because in the circuit, the 5V is connected to +ive rail but then the +ive rail is not connected to anything else.
And when I removed the jumper connecting the 5V with +ive rail, it was still working perfectly. So is there any function to the +ive rail or nothing?
I don't have the starter kit and I'm not following what you're saying or exactly how everything is wired-up...
You generally don't need +5V because voltage is supplied by the I/O pin. The instructions in the starter kit might just be getting you set-up for the next experiments...
When you write a high (or a "1") to the digital output, it goes to +5V.* That output pin supplies the voltage & current to the LED & resistor.** If the other end of the LED is connected to ground (0V), you have voltage across the LED & resistor, current flows, and the LED lights up.
The ATmega chip can either "source" or "sink" current so you can reverse the polarity of the LED and connect the LED & resistor between +5V and the Arduino output. Now when the output is high (+5V) there is no voltage across the LED & resistor and no current flows. But if you write a low, you get voltage across the LED & resistor, current flows, and again the LED lights up.
The I/0 pins can't supply much current. They are intended for "signals" not "power" and they can't power much more than one or two LEDs.
** You need a resistor because LEDs (like all diodes) are non-linear. Their resistance changes drastically with voltage. So we use a resistor to limit/control the current and the voltage across the LED "magically falls into place".
raschemmel:
I have no idea what your talking about.
Post a photo or drawing or both.
the text is self explainatary in this case. you dont really need a pic of ckt for this .
he has just connected to the horizontal rail of the breadboard. this wire is coneected to 5v on of an arduino uno .
thus he has just created a 5v rail on the breadboard.
this 5v rail is not connected to any device . nothing , no led , no device is connected to 5v rail.
he is just wondering that why has he created a 5v rail on the bread board.when he is not using it.
manveen_singh:
the text is self explainatary in this case. you dont really need a pic of ckt for this .
he has just connected to the horizontal rail of the breadboard. this wire is coneected to 5v on of an arduino uno .
thus he has just created a 5v rail on the breadboard.
this 5v rail is not connected to any device . nothing , no led , no device is connected to 5v rail.
he is just wondering that why has he created a 5v rail on the bread board.when he is not using it.
yes, exactly what I wanted to know. And I get it now from the explanation from first answer.
he is just wondering that why has he created a 5v rail on the bread board.when he is not using it.
What is the function of connecting the 5V pin of the uno board to the + rail of the breadboard? Because in the circuit, the 5V is connected to + rail but then the + rail is not connected to anything else
Well the answer is simple. It's standard practice. What if you decide to add something else to the circuit ?
Now you already have a +5V rail you can use.
raschemmel:
Well the answer is simple. It's standard practice. What if you decide to add something else to the circuit ?
Now you already have a +5V rail you can use.
For future reference - It's best if you can include a schematic. If you don't have software for drawing schematics it's OK to had-draw one and scan it. In this case you'd show +5V connected to nothing (except the breadboard) but that's accurate.
A photo or Fritzing drawing isn't as useful because it can be hard to see all of the connections and in general a schematic is easier to interpret (for those of us with electronic experience ).
Of course, the "danger" is the schematic doesn't actually match the physical assembly. That happens and it doesn't just happen to beginners. And since we can't get our hands on your assembly, it's usually something you have to figure out yourself.
That's actually part of everyday troubleshooting when there is an (unwanted) open or short on a circuit board or the board is designed or manufactured wrong, or a wrong or reversed component, or a missing component, so the actual assembly doesn't always match the schematic but it's suppose to!
For future reference - It's best if you can include a schematic. If you don't have software for drawing schematics it's OK to had-draw one and scan it. In this case you'd show +5V connected to nothing (except the breadboard) but that's accurate.
A photo or Fritzing drawing isn't as useful because it can be hard to see all of the connections and in general a schematic is easier to interpret (for those of us with electronic experience ).
Of course, the "danger" is the schematic doesn't actually match the physical assembly. That happens and it doesn't just happen to beginners. And since we can't get our hands on your assembly, it's usually something you have to figure out yourself.
That's actually part of everyday troubleshooting when there is an (unwanted) open or short on a circuit board or the board is designed or manufactured wrong, or a wrong or reversed component, or a missing component, so the actual assembly doesn't always match the schematic but it's suppose to!
Alright. Thanks a lot for the tips. I will keep them in mind.
Yes we have had the same question a few times. I think it was just an oversight on behalf of the person writing the instructions, he modified a previous diagram and forgot to remove that link.
. Firstly, I started from the Starter Guide that came along with it. After understanding quite a few concepts, a doubt came into my mind and its this:
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