In the 74xx_IEEE.lib library, the power connections have different names
VCC, Vcc and Vdd
respectively.
GND, Gnd and Vss.
This is confusing because
the associated connections in the network list are not connected
and
because the voltage connections are sensibly invisible, so that (hopefully) interpretable error messages are generated in ERC.
It seems to me to make sense that the corresponding voltage connections have the same identifier.
In the attached 74xx_IEEE.zip the connections VCC, Vcc and Vdd to VCC and GND, Gnd, Vss to GND have been changed.
74xx_IEEE.zip (16.6 KB)
We intend to get rid of all symbols with invisible power supply pins. Are you the volunteer that finally does it?
By the way i suggest you convert at least the few symbols you use over to not having invisible power input pins within your personal libs.
Good idea, I started with 74xx IEEE.lib and found that at least one symbol must not be derived from the given symbol. (In the example 74LS57 is incorrectly derived from 74LS56. The symbols are similar but not identical.)
How can this derivation be deleted?
I used Kicad Version:
Application: KiCad
Version: (5.99.0-1168-g9d2712a82), release build
Libraries:
wxWidgets 3.0.4
libcurl/7.66.0 OpenSSL/1.1.1d (Schannel) zlib/1.2.11 brotli/1.0.7 libidn2/2.2.0 libpsl/0.21.0 (+libidn2/2.1.1) nghttp2/1.39.2
Platform: Windows 8 (build 9200), 64-bit edition, 64 bit, Little endian, wxMSW
Build Info:
Build date: Mar 29 2020 21:00:49
wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8)
Boost: 1.71.0
OpenCASCADE Community Edition: 6.9.1
Curl: 7.66.0
Compiler: GCC 9.2.0 with C++ ABI 1013
Build settings:
KICAD_SCRIPTING=ON
KICAD_SCRIPTING_MODULES=ON
KICAD_SCRIPTING_PYTHON3=OFF
KICAD_SCRIPTING_WXPYTHON=ON
KICAD_SCRIPTING_WXPYTHON_PHOENIX=OFF
KICAD_SCRIPTING_ACTION_MENU=ON
BUILD_GITHUB_PLUGIN=ON
KICAD_USE_OCE=ON
KICAD_USE_OCC=OFF
KICAD_SPICE=ON
There is a “Derive from symbols” selection list in the “Library Symbol Properties” dialog box, but you cannot select the entry annonced from the information window. (Image
)
There was a discussion about creating the power connections as separate parts of the component. I will not do this because the automatic numbering of multipart components (e.g. 7400: 4 NAND gates) must be numbered manually when using the single gates in different subsheets because of the attribute “All units are not interchangeable”.
The 74xx_IEEE. * Library was downloaded from “https://github.com/KiCad/kicad-symbols”. I hope this is the latest version.
best regards
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