New to KiCad - GND are not connected when run DRC check - and not in PCB layout


I’m new to KiCad but worked with other software. Got some strange issues that I just can’t figure out and hopefully it is just comething simple.

Fresh download of V6 and completed (almost) the first schematic. When I run the DRC check, it states the ground and shield not connected on the USB, which it is. It states VCC is not connected, which it is. When converting to PCB the keyswitches do not have a ground, just the two pins are connected to the same IO of the Atmega.

I’ve replaced symbols, changed the layout and still the same think. Multiple errors. Any help please.

The reset switch does not connect to the reset pin, just ground either side. The

The ISCP header is not connected yet btw.

I did try and atach the errors and multiple images but couldn’t due to new user

Any advice would be much appreciated

You have been ‘leveled up’ one. Try again. :wink:

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ah that typo!

Ah, here goes

The switch is ground both sides but not in the schematic. Even if I directly connect.

Those Cherry MX switches are connected to ground. But not in the PCB

I get an error where the shield and gnd are connected for the USB. Not sure why

Pin 14 is stating that it is not connected but in the PCB I can connect it, so maybe not an issue.

Can’t upload the error file, so here is a screen shot

Hope this helps. Puzzled here and google is not helping ha.

If I make the pin labels visable, then they’re named 1 and 3. Sure it not being 1 and 2 is clashing?

Due to D1 between VBUS and +5V, you’ll need to attach a PWR_FLAG to +5V. There’s a FAQ about PWR_FLAG and when to use it. The GND is already a power output due to the pin type of the USB socket that’s why it isn’t needed there.

You should check if pin 33 of the MCU can be connected to ground like that, it’s typed as bidirectional.

The other errors are just due to unconnected pins. Use a no-connect flag on those pins to silence this warning.

Thanks, I’ll take a read of PWR_FLAG. I did redo the 5V but it strangely changed the error to the next pin. Must be myself doing something strange.

Any suggestions regarding no switch connecting to gnd ind the pcb. Or sw1 connecting to reset.

I double check pin33 and according to other schematics, it should be tied to gnd.

The error can appear anywhere on the +5V net, it just outputs the first one encountered. Be glad it only reports it once.

Somebody else will have to answer your switch questions, I have to run, I’m going off-shift (joke).


Haha okay. Cheers for the direction. Tomorrow for me now

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You seem to have a symbol for the more common 4 pin TACT switch, where 1 & 2 are shorted and 3 & 4 shorted

Most of the errors are of the type:

Error, Pin not connected

Kicad treats any un-connected pin in the schematic as an error.
If you want to leave pins open, then add a no-connect flag to them.

For the shorted switch:
Is the Reset label used anywhere else in the schematic? You can use: Schematic Editor / Edit / Find [Ctrl + F] for that.

If you’re still having some troubles tomorrow, it’s easier for us if you just zip the project and upload it here. Working with the actual project to find errors is easier then working from screenshots.

I thought that about the switch but it’s not like that when added to the schematic or pcb. Will switch it out and see what happens.

Still can’t get my head around the cherry mx switches. They don’t connect to ground in the pcb editor but are in the schematic

Thank you. I’ll add those pins to the unconnected later. Didn’t realise that was there.

I’ll try and add my project but it wouldnt let me add a file yesterday. Not sure how long you have to be a member to do so.

You are already at basic user, so you should be able to attach one file.

Most of the 4 pin TACT switch footprints seem to have two pin 1s and two pin 2s
Seeing pin 3 on the schematic is going to cause trouble. What is the schematic symbol used?

Also turn on hidden pins. This switch symbol may have hidden pins 2 and 4 on top of pins 1 and 3 respectively. You may need to change to a different switch symbol that only has pins 1 and 2.

This is because the link between schematic symbol pins and PCB footprint pads is done by the pin/pad number. Pin number 1 will connect to pad number 1, pin number 5 will connect to pad number 5, pin “number” 3C (for example on a pin-grid array chip) will connect to pad “number” 3C. I put number in quotation marks for the last example because KiCad will allow any alphanumeric symbols (at least ASCII, I don’t know if other international symbols supported by UTF will work) for pin names. The exception to watch out for is the tilde symbol “~” because that historically has been used by itself as a representation for NULL so I don’t know how the current codebase will handle it. Keep to combinations of arabic numerals and english alphabet letters to be on the safe side.

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Thank you all for the advice and help.

So far, I’ve deleted the Vbus and just left the 5V tag but that’s still generating an error with the VCC pin on the IC. Not sure why, I must be missing something with the power_flag.

The switch going to reset has been changed and is all working. I just need to edit the foot print. Next skill to learn.

I’ve changed the Cherry MX switches as the pin numbering was clashing but I couldnt get my head around editting that. But it is all working there. Thanks!

Atmega32U4 Macro (49.2 KB)

Is D1 meant to be in series with VBUS?
D1 is a bidirectional surge limiter and will only conduct when the voltage across it exceeds a bit more than 5V either polarity

Yes, indeed.

Indeed, probably another error.

It is, this is the datasheet. Just as a bit of surge protection.

I get the impretion you’d advise against it?

Probably another error? Go on, what am I missing here? Are you refering to the components chosen or my issues in Kicad?

A surge protector meant to be in parallel with the power input. If you were intending to protect against reverse polarity, an ordinary Si rectifier would do the same job (and lose you 0.6V from the 5V supply). Besides a connector like micro-USB would prevent accidental reversal.