# Learning how to read schematic

Hi,
I am looking for some guidance about how to learn to read schematic and translate it in real life circuit. I got a bit confuse sometime, for example in this tutorial here .
I don't get why the jumper that go to the reset pin of the arduino uno have to be connected between the resistor and the Atmega.In my head the line on the breadboard connect everything that is plug into this line so i don't understand why the order matter.
Does there is any good book that could help me understand this kind of thing ( big plus for the electronice on, i order some of them but i live in Australia and take forever to get them ( if i get them at the end)

All the best

Vincent

The order does not matter of course.

Those are not schematics, but pictures. Some of use (like me) can't get used to the pictures, as I am used to schematics.

There are no schematics on that page you linked to. There are lots of physical layout diagrams which are shit but no schematics. You can google for lots of videos and pages on how to read schematics.
Once you have a schematic there are many ways to turn that into a physical layout diagram and Fritzing is about the worst one you can choose. Simply do it one component at a time and work your way through the schematic.

Hi,

Thanks, yep there is no schematic on this tutorial, i insert it just to show that some of these circuit does not make much sense to me.Like why there is a resistor to the reset pin when the atmega support 5v and the VCC is 5V ?
I start electronic by just copy-paste what other peoples are doing with time my interest grow and i like to understand it a bit deeper.
Thanks for some reason my circuit was not working with the another order ( but should have been about something else ) and it get into my head that order matter.

All the best

Vincent

vdiallonort:
Like why there is a resistor to the reset pin when the atmega support 5v and the VCC is 5V ?

I probably should not stick my nose in here as I am still a noob also and am likely to muck it up.
But I am sure that the reason for that resistor is to limit the current.

While they are both 5v. The Vcc pin can source 200 mA of current and the reset pin can sink only 50mA so a resistor is required to limit the current to an acceptable range to prevent damage.
It's the same reason that LED's require resistors or a constant current supply. without them they will draw more current then they or the arduino can handle and then the magic smoke is released. They are not much good after that.

This is more of a electronic design question than a schematic reading question.

The resistor is called a pull up resistor.

The maximum current for the chip is i/o is 40 ma per pin although other restrictions apply.

For an input only micro amps are generally needed.

’ While they are both 5v. The Vcc pin can source 200 mA of current and the reset pin can sink only 50mA so a resistor is required to limit the current to an acceptable range to prevent damage.’

The current limiting resistor on an led circuit fulfils a similar function.

An output can either be a current source or sink (digitally)
without a current limiting resistor that can destroy a chip easily.

Understanding circuit diagrams is just a question of time and practice.

Do not waste time trying to understand arduino diagrams.

Learn the basics of transistors and other discrete components first.
arduino specifies source and sink current capabilities for outputs, to understand that properly you need to understand basic transistor operation first.

You learn to read schematics AS you learn circuits. Look for good basic sites and it all starts to make sense. Learning to read schematics is the wrong goal.

Boardburner2:
Learn the basics of transistors and other discrete components first.
arduino specifies source and sink current capabilities for outputs, to understand that properly you need to understand basic transistor operation first.

One can download the datasheet of a relative simple device like a 74HC00 and have a look at the electrical characteristics for starters. Most relevant are probably Iil (how much current flows out of an input pin when it's pulled low), Iih (how much current flows into an input pin when it's pulled high), Iol (how much current can an output sink when it's low) and Ioh (how much current can an output source (deliver) when it's high) as well as some Vcc related parameters. Ask questions about parameters that one does not understand.

The gained understanding can next be used to understand the electrical characteristics of e.g. the 328 micro controller without drowning in the surplus of information.

Boardburner2:
Do not waste time trying to understand arduino diagrams.

For me, they are terrible examples of schematics.

Hutkikz:
This is more of a electronic design question than a schematic reading question.

Yep. I agree. And as outofoptions says, “You learn to read schematics AS you learn circuits.”

It’s a matter of getting into studying basic electronics, and as you do so, the various circuit symbols that make up schematics will be presented to you.

Learning to read schematics, without any electronics knowledge, won’t work.

The link in Reply#5 is the only way to learn how to read schematics. Learning the symbols is half of it. The other half is learning to understand why components are connected the way they are. That takes much longer. There is no shortcut. Learn electronics and you will learn how to read schematics at the same time. Try to learn schematics without learning electronics and you will be lost.

Colin's Lab video on reading a schematic

sterretje:
For me, they are terrible examples of schematics.

It's just not me then.

I get flashes of jelly fish in a bucket when i see them

You will constantly hear the regulars in the #Arduino IRC channel groan when yet another bad "pictorial" diagram from Fritzing is 1) called a schematic... {because... it's not} 2) posted so someone more knowledgeable can figure why its not working...

And heck we can't... because all the hookup wires are the same color and crossing each other at crazy angles. Pictorials are horrible at conveying the INTENT of a design, especially when the tool offers NOTHING in the way of design rules.

I applaud the desire to learn schematics. It is the common language we should all speak.

It is the common language we should all speak.

Remember what happened at the Tower of Babel!

.

LarryD,
Ha, ha.
A real schematic is a universal language understood almost anywhere. I admit, if I saw a Russian schematic I wouldn't understand any of the labels but I would recognize the circuits.

That is exactly what happened when I visited The USSR in 1991, my son bought an electronics kit ( for \$1.00 ) and because there were schematics in it he could use it.

How much did the kit cost ?

Do they have a Russian warehouse supermarket Cosco equivilent ?
What is the Russian version of a "fast food" restaurant? (stuffed potatoes?)

Well this was in the days before the fall of the USSR when the street exchange rate was about 50 Rubles to the dollar. It was a rip off kit that cost in the west about \$40. I still have it somewhere.

How many mars bars does that translate to , or should it be mcchicken nuggets these days.