Simple 7803 regulator circuit. I use the +3V3 power symbol to connect the various net together.
But on my ATTINY when I placed this 3V3 symbol and connected to the Vdd I get an erc error , input pin has no output , ( not the exact )
This usually crops up where an input power pin has no obvious input power source
But. A 3v3 power symbol actually get used in both cases ie marking the output of the regulator and elsewhere in the schematic the input to various other nets
I fixed it by placing a power flag. It it’s not great
KiCad V6 does a lot more ERC then KiCad V5, so it’s not surprising you see some extra ERC violations pop up.
KiCad V6 also has an option to set the severity of all ERC types in Eeschema / file / schematic Setup / Electrical Rules / Violation Severity, and you also can suppress individual ERC messages, by first running ERC and then right clicking on individual messages (These exclusions get their own list, and they can be un-excluded later if you wish so).
A long wish of mine is to have an ability to treat things like fuses, filter inductors and chokes, net ties and jumpers as a “short circuit” for ERC purposes. There has been some talk about this on gitlab (quite some time ago) but I have not kept up with this as an “official” feature request.
Assuming that an input power pin is unconnected, just because I feed it through a fuse, or in my case through a ferrite bead, is absurd. Note that I also tried drawing an ugly line because I couldn’t believe those two pins were unconnected…
If that’s not enough, the fourth error reported above is nonsense to me: a ground pin (AGND) connected to the GND power port, along with all the other GND pins, is reported as not driven!
You can’t tell me that’s picky ERC, this is a bug
placing a +5V power symbol does not tell the ERC that there’s power
i recommend getting familiar with how the ERC works
in short:
5V comes from a connector, kicad has no way to know about this, you should put a PWR_FLAG there
the +3.3V doesn’t give an error here because it comes from a regulator, its output pin gives power
similarly to 5V, GND also comes from a connector, kicad doesn’t know this, you should put a PWR_FLAG there
the regulator requires power on its input and its ground pins
power symbols create global nets, and require power
PWR_FLAG gives power, this symbol has the only purpose to tell ERC that “i promise there is power here coming from somewhere”
some symbols can give power on some of their pins (like this regulator, some USB connectors, etc…)
whenever you wonder what’s going on here, you can inspect the pin electrical types by clicking (and holding the button (in v6)) on a pin, until the “clarify” menu opens up, then select the pin and see its type in the bottom status bar
selecting the pin in v6 can be slightly more difficult, alternatively you can see all pin types for the symbol in its properties, or open the symbol in the symbol editor and see the pin types there
