Transforming a schema into a pcb


#1

Hi,

I’ve created my schema (does it have to be without crossing lines ? Cleaner ? Do we care about the positions of the components ?) :slight_smile:

What do I have to do now if I want to make a PCB out of it ?

Knowing the power source is from the Arduino.

Thanks


#2

Now you have to follow a few steps.

  1. Annotate all components. Either manually if you want. Or voa the annotate button

  2. Export netlist. Leave it with the default settings. It will create a netlist file

  3. Open cvpcb. In this you assign the footprints for the components you know.

  4. Export netlist again (some versions need it done again)

  5. Open pcb nee

  6. Import netlist


#3

You don’t need to export the netlist before assigning the footprints.

Regarding assigning footprints, this might be a good read: How can i assign a footprint to a symbol?


#4

Thanks, I’ll try this!

So you confirm that I don’t have to make a clean schema ?

And do I have to add power symbol to the 5V pins of the Arduino mega ?

Thanks,
Julien


#5

Not for the software at least. For your own sanity maybe. For future maintainability absolutely. (labels and buses are your friends. maybe even hierarchical sheets)

the power symbols are just fancy looking global labels. you do not need to use them but they could make your schematic easier to read.


#6

FCU A320…
FCU like in “Flight control unit”, it seems :slight_smile: If your next project is a FADEC, I’m suddenly very afraid. :wink:

Nobody is able to make a nontrivial schema without crossing lines, at least I can’t do it.
Cleaner? For me it’s clean enough. Beauty lies in the eye of the beholder.
The positions, it depends. If you have a signal that follows a path, let that path show on the schema, like input stage, preamplifier, filter, amplifier, output stage. I mark and label such stages on a user layer. On other applications the parts have already approximate relative positions to each other. Or, as you seem to have done, keeping functional groups together. There are no fixed rules.

The next steps might be changing all the “R” in the resistors to the values they will have.
Then annotate all the parts. Run an ERC, fix what needs to be fixed, repeat it until ERC is happy or you really understand what’s the issue and are sure it will work as intended.
Then, assign footprints (assisted by reading datasheets), export the netlist, read the netlist into PCB_new.
Now the fun part begins, turning that mess of parts into a decent PCB.

Walter


#7

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.


#8

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


#9

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.

Thanks


#10

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.


#11

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


#12

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.

Walter


#13

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 ?


#14

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.


#15

image

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


#16

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)


#17

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


#18

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

Do you really suppose someone sets it instead of you?


#19

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)


#20

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:
http://docs.kicad-pcb.org/stable/en/getting_started_in_kicad.pdf
see page 24.