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We start every project by drawing the "circuit diagram", also known as a "schematic" for the PCB we are going to design. Our finished schematic for this introductory exercise will look quite like….
(Please don't think ill of KiCad because of the resolution you see above. The poor resolution is an artifact of the screen capture process. Furthermore, as you work with KiCad, you should get into the habit of using its extremely user friendly mechanism for zooming in and out, and for panning. These will give you nice, crisp graphics to work with.)
What that shows is a place to connect a battery ("CONN_2", lower left), and then, clockwise around the circuit, a switch, a resistor, and an LED. Of course, there is a wire from the place for connecting a battery, and the wire goes all the way around, eventually coming back to the connector.
The diagram is "imperfect" in many ways… but is the result of a beginner's use of eeSchema to design a circuit, and will suffice for now for our needs.
Here's how I drew that….
To start designing the schematic, click the first big icon on the central project manager window, the one for "Schematic Layout Editor"… the rather nicer name used in 5-1-5 for what was previously called "eeSchema".
This "new name"/"old name" thing is going to crop up a lot. The old names are still "around". For instance, eeSchema still (12/19, KiCad vers 5-1-5) appears in the title bar of the Schematic Layout Editor's window.
Before v5-1-5, the first time you invoked eeSchema, you got a "beep" and a "File Not Found" warning. (If you're using an old version, just click "okay" and press on.)
First we'll put an LED, a two pin connector, a switch and a resistor "on the page"….
Be sure the "pointer" icon on the right hand toolbar is selected.
Put the crosshairs in the working area.
Press "A" (for "add component". You can use a lower case "A", "a", but I think the upper case version is more clear here.) ("Component" is a word being written out of Kicad, replaced by "schematic symbol", but as of version 4.0.4 "component" lingered in the tooltip for this.)
(There will be a moment's delay with "Loading Symbol Libraries" and a progress bar on the screen telling you to be patient.)
A "Choose Symbol" dialog will open.
Type "led" into the "filter" (formerly "name") edit box. (You used to have to then press enter.) Find a suitable symbol. (The default result from entering "led" is pretty good, if all is well, but explore your options, if you wish.) Click the "OK" button. That should put you back on the page, with a tiny LED "stuck" to your mouse pointer. Don't click your mouse until futher notice!
Use your mouse wheel to zoom in a bit so that you can see the symbol properly. (Don't get too frustrated with the unusual interface until you have mastered it. Different isn't necessarily bad! The KiCad people have "broken the rules" for reasons which, to me, seem good.) (If you need later to find a schematic symbol by using "Select by Browser", things like LEDs, resistors, are in the "Device" schematic symbols library.)
Press "R" as often as necessary to Rotate the schematic symbol until the arrow in it is pointing down. (This because the schematic you are trying to copy has the LED pointing that way.)
Use the mouse wheel to zoom out again to where you can see the whole page.
Move the cursor, with it's "attached" LED approximately to the right place….
… and click your mouse to "drop" the LED symbol there.
Get it wrong? Put pointer over the symbol, press your delete key, try again. But don't delete it if not wildly wrong… you can tweak things later.
Play about a bit with zooming in and out. When you are zooming in, the zoomed image will be centered on where your cursor was.
Save your work
KiCad, in common with most computer applications, has certain elements of your recent work saved only in the computer's memory, and does not have everything you've done "properly" stored at all times. If "things go wrong", or you have a simple power failure, your work since your last "save" will be lost.
Feel free to save your work frequently. In the Schematic Layout Editor (eeSchema), the button on the top tool bar (left hand end), and the menu entry under "File" talk about saving "all sheets", etc, and give you an option of saving a single sheet.
For the moment, your whole project is a single sheet! Don't be put off by the extra stuff.
You can also use the common "save" keyboard shortcut: ctrl-S
(A little aside about the (old) "no file" warning: KiCad uses a sophisticated… but not overly so… system of simple files to pull together all of the elements of your work. As you start working in each module, the file(s) where that module's result will reside are set up. That was why you got the "file not found" prompts in the old days (pre 5-1-5) the first time in any project's life you enter a particular module… although I think that "feature" went away long before ver 5.)
Carrying on with schematic design
Press "A" again.
Enter "conn_02" into the filter, to get suggestions for a 2 pin connector. Ver 5-1-5, the one called "Conn_02x1 (Generic connectora symbols) will do fine. Press enter.
Move the connector to about the right place…
- use zoom-in/ zoom-out along the way,
- and "R" to rotate the symbol (we want the "2" at the top, "1" below),
- and click your mouse to drop it onto the drawing.
Press "A". Type "spst". Press enter. Position and drop the switch.
("SW_SPST, Single Pole…" in "Switch Symbols" will be good.
Press "A". Type "rsis".
Scroll down the list a bit to get to "R, "Resistor". Double-click on that.
Do NOT press "R" to rotate it… yet. Position and drop the resistor.
We're going to see that things on the schematic can be rotated after being dropped.
At this point, the "Add component" button on the right hand toolbar is probably still the one selected. We need the pointer button selected. You could just click on it… or, if you press the "escape" key once… or maybe twice… you'll find that the pointer button becomes the one selected. This is a small example of the fact that there are many ways to do things… and in some cases, the one that "works" is very inferior to another one that you may be failing to look for, learn. If something you "ought" to be able to do seems hard… look for an easy way!
Take zooming and panning. Yes, there are buttons for "zoom in" and "zoom out". And you can use the pane's scroll bars.
Or… just turn the mouse wheel one way to zoom out and the other way to zoom in. The "scene" will pan to put whatever you were pointing to when you moved the mouse wheel at the center of the new view. With a little practice, "zooming around", if you'll excuse the pun, becomes easy and intuitive. Be sure to make the effort to master zooming, because until you do, being in the wrong place, or at the wrong zoom level will inhibit your productivity and raise your blood pressure… and distract you from the things that are hard!
One last comment on zooming: Use it! It is much easier to select things, move them, get them in the right place, etc when you zoom in as far as you can. You can even zoom in to "pick something up", zoom out to move it to roughly the right place, and then zoom back in again for final part placement, or whatever it is you are currently doing.
Position the pointer over the resistor's symbol. No need to click. Press R. The resistor should rotate.
Wow! Easy… when you get used to doing things this way! (Right click on something (while the "Pointer" tool is selected for a hint of all that lies ahead of you, if you want to become a KiCad Master! Don't worry… you won't need most of those for a long time.)),
Schematic symbols present- now arrange…
Right! Zoom out, so you can see all 4 of the schematic symbols we've put "on the page".
We need to pick one as the "anchor", towards which we are going to move the others. We'll use the LED. We will move it down to the lower right of the page; put it just above the [co1leg legend].
(It may pay you at this stage to open a second copy of http://kicadhowto.wikidot.com/se1sch1 this page in a separate window, so you can use that to display the finished schematic, shown above, while you work on creating your copy of it.)
How to move things
Right click on the resistor's symbol. Depending on exactly where you click, you get different results. This is because you can move….
- the symbol itself, with all its bits and pieces, or
- just the symbol's reference text (we will come back to what that is)
… or…
- just the symbol's value text (another matter for the future)
Before 5-1-5, you might have got the first pop-up menu, just click on "Component…", and you will find yourself at the second one! (Remember when you see "component": KiCad uses the term very narrowly… to mean "schematic symbol".)
Under vers 5-1-5, if you right-click near the "R?", you get….
Under vers 5-1-5, if you right-click just a bit lower, over the "R", you get a very similar sub-menu. Beware! The first line will read "Move Value" instead of "Move Reference".
What, in this case, you really want is to see another similar sub-menu, one starting "Move R?".
Don't worry… if you keep your head, you can "get out of" being in the wrong one. After you've chosen to move something, if you find you aren't moving the symbol itself (and all it's bits), just press the "Escape" key, and things will be back to as they were.
So, ver 5-1-5… you get an offer to "Move Reference", "Move Label", or "Move…" something else. The "something else" will depend on what symbol you are trying to move. The "something else" will be the symbol's current reference.
Whew. Get a cup of coffee?
Continuing with moving things around on your diagram…
Instead of using the mouse right-click, notice the "M" beside "Move". If the pointer button is selected, you only need to put the cursor over the schematic symbol and press M, to pick the schematic symbol up. Be sure you're not moving just the reference text or the value text, but that's no big deal. You'll eventually get used to where to click to get what you want.
To repeat, summarize the above: Once you've picked something up you can move it around. You just move the mouse. If you picked up the wrong thing, press the escape key, and whatever you picked up drops back where it started. If you moved it and clicked, thus putting it down in a new place, ctrl-Z will undo the move. Remember you can zoom out and then back in, on a different part of the diagram, while the schematic symbol is "stuck" to the cursor. To reach the parts that other CAD packages reach differently.
In the old days, sometimes after a change, particularly if you'd deleted or moved something, "debris" remained on the screen. A quick slight "zoom out/ zoom back again" would redraw the page, clearing away the little scraps.
N.B.: Remember that often it is critcal to have the pointer button selected. You'll be surprised how often the button selected changes "by itself". Anyway.
Reminder: While you have the pointer button selected, if you put the cursor over a schematic symbol and press the delete key, the schematic symbol is deleted from the schematic.
You can press the "R" key, to rotate schematic symbols.
You can, of course, reach our goal by many routes. In my case, I next set about moving the resistor schematic symbol to a better spot. I made sure that it was the pointer button that was selected in the right hand toolbar and then right-clicked on the resistor schematic symbol.
For the sake our exercise, now refine the position of the resistor… Zoom in to a view of just the resistor and LED.
Put the resistor above the LED. Do it very precisely, so that the little circle at the bottom/ of the resistor schematic symbol is exactly over the little circle at the //top of the LED's schematic symbol. Then drop the resistor. The two will be connected! (If you fail to line them up properly, the two little circles on the line's ends will still be present.)
Then move the switch until it connects to the top of the resistor. (Again, if you positioned them just right, the circles on the ends of the lines will disappear.)
Finally, move CONN_02x01 to where you see it in the illustrations…
Old KiCad…
Old KiCad vers 5-1-5…
That's it! On to the next step…
Go to next page in Simple Exercise: eeSchema: Connect the devices
