For me it also helps in understanding schematics to make custom symbols.
Vcc connection on the top.
GND connections on the bottom.
Signal flow from left to right.
This just looks weird:
1). Edit the values of your CP1_small to the values of the capacitors.
2). VDDA is probably some power connector, where is it?
I tend to make a nice section where all functionality of the power supply is grouped together in a logical way.
Input connector, buffer & decoupling caps, voltage regulators, PWR_FLAG labels.
But it takes effort and time to make those things a habit, and you have to start somewhere.
Adding my 3 cents. I use one symbol for microcontrollers like that. Than I connect all its pins (except unmovable VCC,. GND, crystal, ISP/PDI) to one bus and name each net in the bus with function in current project. At the last stage of PCB design I change many pin function many times (to allow all my connections be on top with bottom be uninterrupted GND). That needs only to move net names betwean symbol pins and not changing the symbol itself.
You need some physical part to get power into your pcb. Most likely this will be via a two terminal connector. If this is the place simply add a conn_01x02 symbol and connect it to the connector footprint of your choice.
To further expand on Reneâs advice, put the power flag for the VDDA and GND nets connected closely to the connector symbol that you plan on using. This adds documentation to your schematic that the connector is the source of VDDA and GND. (KiCad really doesnât care, but careful placement of elements like this in your schematic will provide self documentation. Much like properly chosen variable names when programming.)
As this project develops I have found the Barrel Jack I need and included it instead of a generic power source. This created an error rather than a mere warning!
I have put Power Flags next to the connector symbols I use.
Mysteriously, Pin 2 on J1 (the Barrel Jack) is not connected to Pin 1 on anything. This is wierd!
If the pin of the connector is already a power output you do not need another power output on the same net. The power flag is simply a one pin component with its pin type set to power output.
The power flag has a single pin with pin number 1.
[quote=âRene_Poschl, post:33, topic:10711â]
If the pin of the connector is already a power output you do not need another power output on the same net.[/quote]
Okay. Because I defined Pin 2 of the Barrel Jack as power output I donât have to do it again. I had defined Pin 1 of the Barrel Jack as Passive so putting a power flag on it didnât help much. I removed both flags.
The PCB puzzled me with the Spider Web Traces but the right things are connected to the right things - except for GND which is not connected anywhere. What classification should ground pins have? I have been making them Passive. RemoteWeatherStation.zip (20.1 KB)
Sometimes I am so dumb I could kick myself! Perhaps I should have figured out all by myself that if certain footprints were missing then the best way to deal with the problem would be to attach them. In this case I had to draw one of them. Anyway, that penny dropped. Sorry to have even mentioned the problem.
There is more poking around to do. I donât know why, but you are still missing your GND net. Even if you have a fill (which I doubt) and you have the fill not showing, you should still see the name of the net on all the ground pins. They all look conspicuously empty to me.
I donât know if it is the source of this, but you have a major problem with your schematic symbol for the nRF24L01+ module. You have multiple pin number 1 and 4s. Reading the pin numbers in what looks like it makes sense, you have numbers 1, 2, 3, 4, 4, 6, 7, 1. The second â4â (SCK) should probably be a â5â and the second â1â (IRQ) should probably be an â8â and have a no connect symbol. But I donât have the datasheet for that module on hand so you should double check that.
Thatâs because the GND symbols that appear in his schematic are not the GND symbol from the KiCad power library. They are the symbol GND-RESCUE-RemoteWeatherStation from the library RemoteWeatherStation-rescue.lib. In that symbol, he has marked the pin as passive. Therefore, he has a symbol which looks exactly like GND, but does not create a global net.
I donât know why this rescue.lib got created but I suspect it has something to do with being unable to write to the power library. I think KiCad creates the rescue.lib to hold edited version of the footprint. Going to the power library in Windows Explorer and giving myself read/write permission seems to work once but it then reverts to Read Only.
I am getting closer to where I need to be but I have an issue with Electrical Types. For instance, I canât figure out what Electrical Type a pin connecting to GND should be. I canât see why it would be Power Output or Power Input, and bit Passive and Bidirectional give confusing results - sometimes they seem to work and sometimes not. Here, Bidirectional does not:
The absolute number assigned to a power rail is irrelevant as far as the physics are concerned. All that matters is the potential between two rails. So, you could rename +5V to be GND, and rename GND to be -5V, and it would be weird, but completely correct.
I just donât get this.
(1) Pin 2 on RC1 is not driven but Pin 9 on IC1 is
(2) Pin1 on U3 is not driven but all the other GNDs are
(3) I canât see why Pin2 of U2 is not driven.
If I wasnât already crazy Iâd be headed in that direction. I am starting to believe that KiCad has something against me and is dreaming up glitches at random. How can a trace work in one instance and not at another?
See your previous post in this thread. Can you see what is different? (See your third sentence). ERC will check that the state of each of the pins at each end of a net are consistent. Just check what types are at each end of your net and whether they will connect together. Working through this logically should show you where the problems lie.
Learning ECAD is hard. As well as the Kicad documentation and the âGetting to Blinkyâ series, this website http://kicad.txplore.com/index-page_id=309.html has several good tutorials to work through. This section is about hidden pins and power flags http://kicad.txplore.com/index-p=156.html might be worth looking at for some guidance your current problem. How to use power flags is not immediately obvious but fairly logical when you think about it.
I absolutely admit that I am no expert (and EDA is not my day job) but personally, I think you might find it helpful to run through a several complete tutorials like this from beginning to end. You will pick up a lot of hints and tips on the way and understand why certain things are like they are. If you run through the whole series you will have a better understanding of the goals and requirements of each stage of the design process. Whilst trying to get your pet project up and running is a good learning exercise, I think you would make quicker progress if you worked your way steadily through a good guide, making notes as you go and refer back to them frequently. You have to have a certain eye for detail and consistency to ensure the electrons actually go the way you expect them to⌠Best of luck.
Perhaps I should have figured out all by myself that if certain footprints were missing then the best way to deal with the problem would be to attach them. 
Anyway, that penny dropped. Sorry to have even mentioned the problem. 
Okay! 
Iâll give that a whirl and see if I get any GND net on my pcb.
I am starting to believe that KiCad has something against me and is dreaming up glitches at random.
How can a trace work in one instance and not at another?