Tutorial: Starting a new footprint
You understand that if you see module, you should think "footprint"? (If not, open the link in a new tab, study, close tab.. and you will be back here!)
You've set up a new footprint library for your custom footprints? (If not, there's a long tutorial to get though first. Follow the link.)
Good! Now we'll go over creating new custom footprint. We'll only cover establishing the new footprint here, so the tutorial can be short. I'll write a longer one later about editing it, getting it Just Right.
Open the thing called "PCB Footprint Editor". Be careful you are not opening something to edit schematic symbols. The one you want has "Footprint Editor" in the title bar of its window (KiCad vers 4-0-4).
Note: You are in an editor that is primarily for changing the definition of footprints. You are not, particularly, editing the library. (Although you may "edit libraries" along the way: You can add or remove footprints from them.) (For a short note on removing a **schematic symbol** from a library, follow the link. I believe there's somehting similar for removing footprints.)
Starting a new footprint
You have two options.
- You can create a new footprint (aka "module") from scratch
- You can load an existing footprint, and tweak that.
Both have their place. If you are very new to this, I would recommend that you use the second option for now. (To start one from scratch, there is a "do it" button, and a "do it with wizard" button. In the following, I'm going to show you loading an existing footprint and tweaking it. From as soon as we've loaded the existing footprint and saved it for the first time (as a new footprint), the two exercises are the same.)
For the purposes of this tutorial, you would probably be fine with any simple footprint. I happened to use the "standard" footprint from the "Capacitors_ThroughHole" library, the one called "C_Axial_D5_L11_P18".
To load it, I drilled down to it with the browser, and then double-clicked on its name.
I then clicked "File | Set Active Library", and set the active footprint library to the one I set up earlier for holding my customized (and third party) footprints.
And clicked on…
… to save our (as yet unchanged) new footprint. That gave rise to a dialog inviting me to give the new footprint a name. This can be quite verbose, as it is only for "footprint picking" lists. (The button is sometimes grayed out until some change has been made to what is on the page. Not here, as far as I know… but in other parts of the KiCad system.)
BEWARE: The footprint will be saved to the library under whatever name you specify… even if there's a footprint of that name in the library already. There will be no warning to tell you that you are overwriting something. While this is good when you are replaceing a "step along the way to the final product", it is not so good if you accidentally re-cycled a name you used earlier on a completely different footprint!
Now "play with" the loaded footprint. Change pad sizes, move them around, change the lines on the board in the silkscreen layers.
For now, I would steer clear of adding or removing pads. (or pins, if tweaking a schematic symbol.) Start with a footprint that has the number of pads you need.
(For the future: When you work with footprint definitions (and the definitions of schematic symbols), there are two sides to the process. You tweak what the user sees on the screen… but you also tweak the values in various property fields. This latter activity can be a bit tricky at first. Happily, it "only" messes up the operation of the electrical rules checker (eeSchema) and design rule checker (PcbNew)… but these tools are important. You should use them. You should learn to create schematic symbols and footprints which support them. but you can do that later!)
So! There we have it! A new footprint started. And saved in our footprints library. Doing more editing is a topic for another page.
Switch over to PcbNew (no need to shut down footprint editor), and see if you can place an instance of your new footprint on the PCB design!
Along the way to completing the exercise, you may have made sundry false starts.
Close down all KiCad modules. (Always do this before any tinkering with the KiCad files.)
Use your operating system's ordinary file management utilities do hunt around for traces of those scraps. In most cases, you can just delete file. In particular, in this case, .kicad_mod files. (If you used one of the definitions you have deleted in a project, and have forgotten, you will probably never even notice the problem: The project will be working from a copy of the definition, which it took at the time you used it. If you delete a whole .pretty folder, if your project had been told to include that library in the ones it consults, you'll get a "complaint", the next time you boot KiCad… but you only have to remove the now-gone library from the ones the project should consult. That will fix things.
Once you have a few schematic symbols in your library of them, you can use one of them for the starting point of another, of course.
Of course, you've much more to learn about footprint creation before you are "done", but what you've been shown here is an important "foundation skill", andone of the "hard bits" taken care of.