I want to check my connections and immediately I have difficulties connecting +3.3V supplies together.
I have +3.3V connections of my own and original from a Kicad file of Raspberry pi io board. I can select my own +3.3V pins like in the picture or from original, but not both. It looks like I should not select +3.3V from components, but how then I should do it.
There are a couple issues.
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The labels need to match EXACTLY.
3.3V is not the same as 3.3v -
I suggest you use the standard power symbol in all instances. This is correctly done on U17 and U10 as shown in pink.
Do the same for 1.8v
And the difference between “3.3v” and “+3V3” is even more bigger.
There can also be more complex issues.
The way power symbols are handled in KiCad is that a global label is derived from the pin name of the power symbol, and the pin name usually is hidden. What you see is the symbol name, and those can be different. Especially if you modify power symbols youself (or someone else before you) it is easy to make mistakes here.
Yes. I noticed something like this, too now.
I think Raspberry IOmodule is made with Net labels and +5v and +3.3v names.
paulvdh Do you mean that those nonstandard names are not necessarily automatically connected to pins.
I dunno.
I’m just staring at some pixels.
Apparently you started this thread because they are not connected, and that answers your own question.
It looks like you have turned: Eeschema / View / Show Hidden pins turned on, which also shows the vertical pin names in your “+3V3” symbol.
The “+3.3v” is a local label. Local and global labels do connect to each other, but only if they have the same name.
So first click on: Eeschema / Edit / Find and Replace and then fill in the form like so:
Then keep on clicking on Find until you’ve found them all, and only replace the strings you think should be replaced.
If it still does not work after that, it’s time for the next step.
Hmm, I think you should pay some attention to what is powering what. I think you’ll find that Arduino has a regulator to convert 5V to 3.3V. If you then provide a 3.3V supply from somewhere else and connect this to the Arduino’s, who knows what will happen. Even if you use the Arduino as a single source for the 3.3V rail, you need to pay attention to the current limit of the Arduino’s regulator. So it’s not only a matter of getting the labels right. NB: I have not looked at your design, this is just general advice.
That is indeed good general advise, and this is alarming at first sight:
Connecting the outputs of different power supplies together is usually not a good idea.
But there are some mitigating circumstances. First, it’s not an “arduino” (They get no capital “a” from me, but that’s another story) but an Raspi I/O board, and I assume the power itself is taken from the main Raspi connector.
From further reading I got the impression that LM21 uses the name “power supply” for a power symbol in KiCad, and that is just a fancy way of labeling wires and connecting them together. When the discussion went in the direction of the labels, I got … distracted from the “connecting power supply” wordings.
OK. Bad choice of words from me. I am not connecting power supplies together, but power supply pins of ICs. What are they called, power pins?
By the way, about local and global labels, I still think local net names connect together nets with same name across the whole hierarchical schematic diagram, don’t they.
They’re called Power symbols.
Schematic symbols that add a power connection / label.
Local labels only connect with a single page.
Global labels connect throughout all sheets.
Hierarchical labels only connect through the hierarchy.
I have not read the tutorial below, but it spends quite some text on explaining about labels.
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