Creating, Editing and Updating Symbols and Schematics

Symbol Generation

Once a device has been built in an FPGA database, PADS I/O Designer can generate Functional block and PCB symbols to represent it. You can then export these symbols to the schematic or to the central library.

PADS I/O Designer also generates part information. You can generate a complete part and export it to the local schematic or the central library. When you export parts to the central library, it is recommended that you place every pin explicitly on a PCB symbol, since central library parts are intended to be generic, available for use in multiple designs.

Note
	The PADS I/O Designer tool requires read/write access to library partitions in the central library. If the PADS I/O Designer tool displays an error message regarding library object partition access, use system tools to modify the central library directory permissions and library object partitions to allow full access. See Configuring Library Permissions.

See “Typical Design Flows” for guidance on which symbols to generate for your design process.

Functional Block Symbols (or simply Functional Symbols) are used on functional-level schematics. Ports in functional blocks are equivalent to signals in an HDL unit (VHDL entity or Verilog module).

PCB symbols are used on board-level schematics, as the representation of a physical device. Ports in PCB symbols are equivalent to pins in the physical device.

There are two methods which can be used to create new symbols in PADS I/O Designer:

• Generate symbols using the Symbols Generator.

• Build symbols in the Symbol Window using the symbol editing tools. See "Building a New Symbol".

PADS I/O Designer supports heterogeneous symbols; several symbols belonging to one logical unit. All functional blocks share signals from the database, and the signals are not normally duplicated on different functional blocks. Each PCB symbol in PADS I/O Designer belongs to a functional block and should only contain pins that are assigned to signals placed on that functional block. There may be one or more functional blocks, and each of them may contain one or more PCB symbols, forming a hierarchy, which is directly represented if symbols with schematics are generated. Each functional block is then generated as a symbol with attached schematic. The schematic contains all PCB symbols belonging to the functional block, and the wires attached to the PCB symbols pins in the hierarchical schematic represent the pin assignments.

Only one symbol may be edited at a time. To switch between symbols, you can use the list at the top of the Symbol Window. You could also browse through the available symbols by using the two arrow buttons in the bottom-right corner of the Symbol Window.

Note
	In earlier versions of PADS I/O Designer, Symbols Generator was referred to as Symbol Wizard.