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Attributes
Attribute Editor in BoardMaker3BoardMaker3 supports a powerful attribute mechanism. Attributes can be associated with
different objects and the value of the attribute can be modified in a number of places. A typical
attribute might be the "Value field" for a component, such as 10K for a resistor. It
is most common to associate attributes of this type with a specific package. For example,
an 0603 surface mount resistor package might have attributes of tolerance, voltage, watts
and so on. These attributes are specific to the device. However it would be tedious to
have to create a different package for every 0603 resistor and the "Value field" attribute
could be modified at the schematic stage. This latter choice would of course violate
the "one package for one physical device" concept described above, but there is a solution
for this below (see importing/exporting).
BoardMaker3 also supports schematic-wide attributes.
Typically this is information that is disseminated to every page of the schematic and often includes
data such as "drawing name", "revision level" and so on. These attributes can be picked
up by symbols which reference them. These are typically drawing templates.
Importing/Exporting Attributes
One of the most powerful features of the attribute mechanism in BoardMaker3 is the ability to
import and export attributes from a third party spreadsheet tools. The attributes of
all the components can be exported in a CSV(comma separated value) file and modified
in an external spreadsheet/word processing tool. New attributes can be defined and (selectively)
added to components. When the attributes have been modified, they can be re-imported and
BoardMaker3 will update the attribute values and create new attributes as required.
Bill of MaterialsThe Bill of Materials (BOM) output from BoardMaker3
also links the attribute data and the software comes with template macros for Excel to provide
suitably formatted output. A special macro is provided which will identify components
that are present in different build variants and automatically produced sets of BOMs for
the different builds.
Attribute transfer
When using the Schematic/PCB linkage mechanism (described below) to transfer data from the
Schematic to the PCB, all the attributes are also transferred along with the netlist. Any
attribute values can then be displayed on the silk screen of the PCB. The default attributes
to display can be defined at the PCB symbol creation stage, but these can be added or
removed as necessary when the PCB symbol is used. Attribute values are dynamic and updating
an attribute on the schematic will automatically update the attribute on the PCB.
Intelligent wires and busesBoth wires and buses have an intelligent connection
system. When a wire starts from the centre of another wire, the software will automatically
add a junction dot. A wire that is left unterminated will be flagged as an "orphan" and a symbol
that has a pin which has not been connected will similarly be flagged as a "widow". There
is no need in BoardMaker3 to use a special object to connect a wire into a bus, just
terminate the wire at the bus and the wire will automatically be incorporated into the
bus. If you place an IO port onto a bus, it will automatically pick up and format all
the names of the nets which are attached to the bus.
The PCB & schematic linkage mechanismBoardMaker3 provides a transparent mechanism
to link schematics and their corresponding PCBs. Once a schematic and PCB have been linked,
changes in the connectivity of the schematic can be reflected to the PCB with a single
keystroke function. Components that are deleted on the schematic will be removed from the
PCB and new components will be added to the unplaced component bin in the PCB editor.
Likewise, if a PCB is renumbered, the new numbering scheme will automatically be reflected
back to the schematic. The linkage mechanism avoids the need to generate netlist files
or "was-is" files for backannotation after renumbering (although these files are supported
to enable the schematic and PCB tools to communicate with other third party tools).
Place from schematicOnce a schematic and PCB have been linked,
there are a set of additional features which are available. One of the most useful of these
is the "place from schematic" tool. BoardMaker3 supports the MDI interface which means that
several documents can be opened simultaneously. If the user selects place from schematic on
a symbol in a schematic window, the software will automatically match the component in
the PCB window and begin placement. This feature is particularly effective with large displays
or when using multi-head graphics displays which BoardMaker3 fully supports.
Cross probing
Another feature that the linkage mechanism provides is "find corresponding symbol", widely
known as cross-probing. Clicking find corresponding symbol on a schematic symbol or pin in the
schematic editor will switch to the corresponding PCB (loading it if necessary) and pan the
screen to the corresponding symbol. This works equally from the PCB back to the schematic.
Pin swapping
The linkage mechanism also transfers information regarding pin swapping to the PCB editor.
There are two pin swapping functions supported in the schematic editor of BoardMaker3, a
single pin swap and a multiple pin swap. The latter function is used for flexible devices
(such as FPGAs) whose IO can be defined as virtually wholly swappable. This is useful
when the PCB layout drives the pin numbering assignment on such devices. The PCB editor
also supports the single pin swapping mode and changes made at either the schematic or
the PCB will automatically be reflected to the other via the linkage mechanism.
Miscellaneous
Pre-routes and multi-pin functions - BoardMaker3 supports an ingenious features which allows
the user to define connections that are "internal
to the physical device". There are several situations where this is useful such as keyswitches
which provide the same switch contacts at several pins. There are several components
on the market, such as FETs which have alternative connections eg. for drain or source. The selection
of the pin to be used is often dictated by the layout. BoardMaker3 calls these internal
connections pre-routes. A similar mechanism is also provided to allow one logical function
to span multiple pins. This is typically used to allow for variations in the number of power
connections on alternative packages (PLCC, QFP etc), but it can also be used when a device
has more than one pin which fulfills a specific function, for example, there are some high
current opamps which spread their "output" over several physical pins. This allows the
"standard op-amp" symbol to be used in conjunction with a device which has multiple output pins.
Merge nets
A merge nets function is provided in the schematic editor. A design can be created with, for
example, separate analog and digital grounds, but for the purposes of netlist generation
(to comply for example with EMC requirements), these ground signals can be merged before
proceeding to the PCB editor. See also "Star Earth Returns" in the PCB editor.
Schematic drawing sizes & templates
BoardMaker3 supports all paper sizes up to 40 inches square. Schematics can have any
number of pages and connections between pages can be controlled either via the global net
mechanism (typically used for power connections) or via the IO port mechanism (used for signal
connections, both individual and bus-based). Some common sized drawing templates have been
provided and the user is free to tailor schematic templates as necessary. The printing options
will automatically accommodate for mismatched template and printer sizes offering a range
of solutions including auto-fit, posterising, printport cropping and rotation.
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