Using ERC sounds a bit erratic to me

[roboya]

Hello!

I’m trying to use ERC, and I have a few issues.

1. ERC window disappears.
   I have been misunderstanding it for a while, but I noticed that the window disappears
   everytime I use it. Well, not everytime, but quite a lot.
   Example:
   Right now I have 9 errors and a few warnings.
   When I choose ERC (clicking the icon on top), the current errors are displayed.
   When I click “Run ERC” to update, the window disappears. Not everytime, but often.

2. When the error window stays, clicking one error / warning make it disappear. Not everytime
   either. For instance right now the first line (error) makes the window diappear. The second line
   (warning) doesnt. I have thought it might be specific to warnings. It’s not. As I got a few occurrence
   where it disappears on second click, but it seems unrelated. It disappears on first or second
   click only. Whether it’s an error / warning doesn’t matter. Whether the error is in another page
   also dosn’t matter.

Would it be possible to keep the window open until I close it? I mean : whatever happens,
error or not, warning or not, all errors solved or not, keep that window open.

Now, I have also issues unrelated to window closing.

1. Input power pin not driven by any output power pin.
   I have read about this, and adding a power flag seems to solve the problem.
   In my case, I have a switching regulator output connected to +5V. Isn’t it sufficient to make
   all the 5V symbols potentially power sources?

2. Warning: a pin with a no connection flag is connected.
   The following chip is an RTC.

I have verified in the symbol that the pin MFP (multi function pin) is properly defined
and at least it’s not defined as “unconnected” (see belwow).
Beside this, there is no unconnected cross (x) in the schematic.

Can anybody explain me the meaning of this message?

Thanks,

By the way: my PC config is as follows:

---

Application: KiCad x86_64 on x86_64

Version: 7.0.2-6a45011f42~172~ubuntu22.10.1, release build

Libraries:
wxWidgets 3.2.2
FreeType 2.12.1
HarfBuzz 2.7.4
FontConfig 2.13.1
libcurl/7.88.1 OpenSSL/3.0.8 zlib/1.2.13 brotli/1.0.9 zstd/1.5.4 libidn2/2.3.3 libpsl/0.21.2 (+libidn2/2.3.3) libssh/0.10.4/openssl/zlib nghttp2/1.52.0 librtmp/2.3

Platform: Ubuntu 23.04, 64 bit, Little endian, wxGTK, ubuntu, wayland

Build Info:
Date: Apr 17 2023 07:57:55
wxWidgets: 3.2.1 (wchar_t,wx containers) GTK+ 3.24
Boost: 1.74.0
OCC: 7.6.3
Curl: 7.85.0
ngspice: 38
Compiler: GCC 12.2.0 with C++ ABI 1017

Build settings:
KICAD_SPICE=ON

[retiredfeline]

@roboya

Isn’t it sufficient to make
all the 5V symbols potentially power sources?

No that’s wrong, we already explained this in your other thread.

[mf_ibfeew]

Warning: a pin with a no connection flag is connected. The following chip is an RTC. … Can anybody explain me the meaning of this message?

This message normally means: somewhere on net “RTC_OUT” (supposed the warning is pointing to that net) is a pin either with an extra “unconnect flag” (the unconnect cross from right toolbar) or the pin is internally defined “as not connect” (with your shown pin-dialog). Sadly the warning-arrow doesn’t always point exactly to the pin with the noconnect-setting. So you have to check all pins on that net (seeing the global “RTC_OUT”-label I assume there are more pins connected on different sheets).

Regarding the ERC-window: there was a bugfix for ERC-window-display. Try a update to v7.0.3 and look if it helps. (if you use database-libraries maybe wait with update, there was some rumour about 7.0.3 and db-libraries yesterday).

And the always valid sentence at the end: if you after extensive research still not find the cause for the warning: attach the project in this thread

[roboya]

Hello!

No that’s wrong, we already explained this in your other thread.

I got it, but what I meant:
For example, you have a regulator (like in my example) and you attach to it a +5V power symbol.
As Kicad doesn’t have any knowledge of the circuit, you add a power symbol anywhere on the
5V net, but preferably at the output of the regulator. And this tells Kicad that all 5V occurrences
represent a power source.
From there, I don’t understand why Kicad wouldn’t figure out it’s a source spitting current in a load.
And this power flag would be needed only once.

Beside this, it doesn’t sound beyond technology to consider that a regulator output, declared as
power output, could be considered bu Kicad as a power source, and therefore any net connected
to it would become a power source (for instance 5V), and any power input connected to this 5V
would be considered as a load.

How do you guys add power to a chip? For every power symbol, do you add a power flag?

Thanks?

[retiredfeline]

@roboya

And this tells Kicad that all 5V occurrences
represent a power source.

The ERC rule in question is: If there are any power input pins on the net, there must be exactly one power output on the same net. This catches the cases where there is no power supply or conflicting power supplies are attached.

The 5V symbol is just a regular symbol with 1 pin labelled 5V. This causes all the places where it’s attached to belong to the same net. The pin doesn’t have the electrical type power output. In fact it is a power input pin.

The 5V symbol or rather its pin is not the place to label as power output electrical type. It’s the pin of the power source that should be labelled power output.

If you are using a regulator or a battery, then you will not need PWR_FLAG (once! per net) provided the symbol pins are correctly typed. Other situations like where the power comes from a connector then yes you will get the message that power input pins have do not have exactly one power output pin on the net, and you then add a PWR_FLAG.

So the key is that power supplies like regulators should have correctly typed pins. Then the ERC rule works.

[retiredfeline]

BTW, I think you have been using +5V global labels to connect different parts of your schematic. That’s redundant. The 5V power symbol works like a global label. All that places it’s attached to become the same net. So if there is no power output pin on that net, then a PWR_FLAG anywhere on the net will satisfy the ERC rule. Usually people attach PWR_FLAG to a power connector pin.

This is part of my schematic. Those 2 PWR_FLAGS are the only 2 in the whole schematic. They satisfy the ERC rule for the +5V and GND nets.

[roboya]

Hello!

Thanks for your reply.
Great, that’s exactly what I was expecting: set a flag at any point (for example close to the power supply’s symbol, in your case apparently a connector), and Kicad knows what it is. I tried that, but only the first error disappears, I have one error of the same kind somewhere else.

[roboya]

Hello!

Thanks for your reply.

@mf_ibfeew

Try a update to v7.0.3 and look if it helps.

I checked, but 7.0.3 is not ready yet. Do you mean a nightly build ?

[retiredfeline]

It was just released, it will take time, depending on the distro, for the volunteer packagers to make packages. Hang in there.

[roboya]

Hello!

Thanks for your reply.
Another error I get with ERC. Not erratic for this one, but I would like to know what I’m supposed to do in this case. I’m using a Li-Ion charger. 2 pins of the chip go to the battery, and they are linked together, that’s how it’s intended to work. Same for Vout (which goes to the system, MCU, etc when plugging the power cable when the battery is too low. Kicad reports: error: pins of type Power output and power output are connected. The pins have the same name, so there is no ambiguity to the fact that they are one single net. What can I do? Well, I can ignore the error and delete the marker, but I would like a clean fix.

Thanks,

[retiredfeline]

Well I would say that that the chip pin types should be changed. Since it’s both capable of input and output, maybe it should be passive. Or you could argue the same for the battery, it takes power both directions. Edit: in fact I think it should be the battery that should have the pin type edited as the one in the library is non-rechargeable.

Anyway the purpose of the ERC is to highlight possible problems. Since you know what you are doing, you could just mark this particular error/warning as ignore. Right click on the message and you get choices.