User Guide

The addlevel of Next means that as these gates are placed into the sche
-
matic, they will be used in that sequence, i.e., the sequence in which they
werefetchedintothedevice.
Then place the PWRN symbol once, using addlevel Request and
swaplevel 0.Namethisgate P.
Addlevel Request specifiestwothings:
•
Thesupplygatewillonlybefetchedintotheschematicifre
-
quested,i.e.withtheINVOKEcommand.TheADDcommand
willonlybeabletoplaceNANDgates.
•
Thesupplygatewillnotbeincludedwhennamesareallocatedto
theschematic.WhereasanICwithtwonext-gatesappearsinthe
schematicassomethinglikeIC1AandIC1B,anICwithone
Next-gateandone Request-gatewillonlybeidentifiedasIC1.
So use the CONNECT command to define the housing pads to which
thesupplypinsareconnected.
8.4 SupplySymbols
Supply symbols, such as might be used in the schematic for ground or
VCC, are defined as devices without a package. They are needed for the
automaticwiringofsupplynets(seepage 88).
The following diagram shows a GND symbol as it is defined in one of
thesuppliedEAGLElibraries.
Note that when defining your own supply symbols, the pin and the de
-
vicenameneedtoagree.
The pin is defined with direction sup and has the name GND. This
specifies that the device containing this symbol is responsible for the
automatic wiring of the GND signal. The text variable for the value
(>VALUE) is chosen for the labeling. The device also receives the name
GND. Thus the label GND appears in the schematic, since by default
EAGLEusesthedevicenameforthevalue.
It is very important that the labeling reproduces the pin names, since
otherwise the user will not know which signal is automatically
connected.
The pin parameter Visible is therefore set to off, since otherwise the plac
-
ing, orientation and size of the pin name would no longer be freely se
-
lectable. Directly labeling with the text GND would also have been
possible here. With the chosen solution however, the symbol can be
usedinvariousdevices(suchasforDGNDetc.).
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ComponentDesignExplainedthroughExamples