Transforming a schema into a pcb


Okay thanks I’ll do this and run the ERC until everything is ok.

And yes this is for the A320 fcu, I’ve made one for flight simulator but all the wires going out behind drive me crazy it is too hard to plug in the arduino and there is no common ground so I have to use the protoboard and this is not safe regarding connections.

And by the way the next project is fadec, but it is only about potentiometers and few switches so it’s okay :slight_smile:

Do I also have to change the 5V, VCC inputs as power input type, power output type or do I let everything passive ?

I’ll keep you update, thanks for the help.


If you leave everything passive, erc can not help you that much. might be a good read: Electrical type of schematic symbol pins


I’ll read that now thanks.

And what if I want only round holes to solder the wire I already soldered to the components ? Because footprints give you the hole for the component not for a wire.



Absolutely true!

Just putting GND and 5V symbols instead of tracing those long wires would clean a lot the schema. And wires don’t going through component symbols too.
As Rene said, only for own sanity it will pay off.


specialized footprints.
maybe use some connector footprint as that will allow you to maintain your stuff more easily.


The holes where you intend to solder wires in will be round in most cases anyway. The shape of the copper area with the hole in it doesn’t matter much for soldering a wire instead the pin of a case. Slots would be different, but not much of a hindrance. You can always make your own footprints.
It’s personal preference, but I like to have connectors on the PCB where I can plug in a (ribbon)cable. For me it’s worth the cost for pins and headers or real connectors to be able to easily remove a plugged in component to replace it with something for testing, or to remove the board for improvement (or repair) without either removing all the wires from the PCB or all the switches and LED’s and whatnot’s from the front plate.



I have 23 remaining errors, dealing with types.

I chose output for the pin of my arduino. Then output for the “+” pin of the LED (but activated with an output of the arduino) then power input for the GND pin of the LED. Should I use power input for the “+” side too ?


both pins of an led would normally be of type passive. (an led is a passive device)

regarding power input: read the specialized section about power input of the faq article linked above. it basically states that both a gnd and v+ supply pin of an active device are power input.

the key here is that it is power input not current input.



There are strange things going on here, 3 funny loops, 2 other loops through symbols, 2 lines to nowhere. And I’ll second


I am also worried about the fact that a lot of leds in parallel seem to be directly connected to a micro controller. It might be that this will result in too much current over a single gpio. Using a transistor might be a safer option (gate of Nmos to uc output. source to ground, drain to the led)


I have updated the schema, and I don"t have any errors anymore :

I have associated symbols with components (I just don’t find the arduino mega one)

When it comes to power, I calculated that it would be ok with the Arduino thanks to the resistors. (Not above 20mA per pin + not above 200mA overall) But I would like you to explain how to use a transistor because I never did… :frowning:

Can I set my PCB size ? Because I want it to be te size of my front plate of the FCU which is 256mmx82mm. (I don’t want to make a pcb as little as possible I just want to place the components where they have to be and that’s all)

Thanks for the help


Have you checked if your LEDs powered by 5k from 5V are bright enough?

Do you really suppose someone sets it instead of you?


Have you checked if your LEDs powered by 5k from 5V are bright enough?

Yes it is okay for what I need.

Do you really suppose someone sets it instead of you?

Of course not but I have this A4 sheet (which I can change dimension) but is there any tool to draw the contours and draw landmarks to set the position of the components (like in illustrator of photoshop)


I am KiCad beginner also (one KiCad PCB behind me). Any lines at layer Edge.Cuts KiCad understands as edge cuts. When you Plot gerbers only what you painted is plotted (not the A4 frame).
It looks you are the next one who didn’t read the:
see page 24.


You have actually applied 5V through a 5K resistor using the LEDs you intend to use? This will result in less than 1ma through the LED.

FreeCad is the MCad of choice for most on people on this forum.


Something like this could do the trick.
R1 might be a bit overkill. (with it and R2 you could divide down the voltage at the gate of Q1. The bss205 i typically use can handle gate voltages of 12V so for it you would not need R1 at all. (R1 can be 0 ohm in that case.))

R2 is there to reliably turn off the transistor while your micro controller (uC) has not yet initialized its pins. (might not really be necessary in your application.)


I only asked not argue as recently I used bright green LEDs for which I have to give 0.5mA to make them not be too bright.


I Tried it and the brightness was ok to me.

I tried to import a dxf file but nothing appears.

And is there a possibility to lock some components and then auto-route while letting the possibility for other components to be placed anywhere ?



The tie dots you can see show the connections. Generally avoided is a tie dot on a cross ( ie T is ok) but you have avoided that.

Cleaner is always good.
Extra corners make it harder to scan, and crazy loops (!) like on the bottom left LEDs are easily avoided.
Where lines are similar, (as in those 3 leds) run them adjacent parallel, and use the saved space to spread the others to clearer scan.
You can do quite a bit of corner-reduction on that SCH

Not really, but placement ‘broadly similar’ to the PCB design makes things easier to find.
Usually that means in small clusters of parts, the numbering order is similar.
Tends to happen naturally, but can need some manual help…


KiCad itself does not care about the “neatness” of the schematic.
Humans do, but some care more then others.

This is probably one of your first KiCad projects.
If you are OK with how the schematic looks and just want to make a PCB, then go on with it.

If you want to make comprehensible schematics that you and others can easily read / modify / maintain, then learn to use GND / Vcc symbols and local labels.

Euhm, do you have a connector as a power entry point, or are you suing the power from the arduino board?