Symbol Editor may be used to edit symbols and add specialized pin setups.
Pin and Gate Swapping
A pin swap is defined by the PINSWAP property. For example, in the AND gate pictured below, the pins A and B are interchangeable. To indicate this, the pin names "A,B" have been filled in for the PINSWAP property. Note: Ensure that you use the pin name, not the pin number.
Power and Ground are shown on the symbol (Explicit) and are repeated in the pins table GND 7,7,7,7 and VCC 14,14,14,14 to show how they group with A, B, and Y.
Gate Swap for Layout
Gate swapping may occur in Layout and requires special schematic symbol creation to map the gates together . Users may want to swap gates in Layout to make connections more straight forward. When imported into Layout with the ECO toolbar activated for Gate Swap, it is now simple to swap the gates by selecting one gate, represented in white, and then selecting pin of a gate in yellow.
Equal, and therefore swappable, gates are defined by filling in the PARTS property and by listing all pin numbers with the same function under the appropriate pin name in the pin table. For example, the value "4" is filled in for PARTS in the image below, indicating that the component contains four equivalent gates expressed by the symbol. Four pin numbers have been listed for each pin in the pin table.
Power pins must use the SIGNAL property (Implicit) for Gate Swap to work and are not shown on the symbol.
Pins Table Setup
- All A inputs are listed for A 1, 4, 9, 12.
- All B inputs are listed for B 2, 5, 10, 13.
- All Y outputs are listed are listed for Y 3, 6, 8, 11.
Properties Table Setup
- Power and Ground must use SIGNAL property. SIGNAL property is repeated for each power connection. For example GND;7 or VCC;14.
- PARTS property shows the number of equivalent gates. In the example below, this is set to 4.
Click to expand each image.
Implicit and Explicit Pins
Please see below an example of the use of implicit pins.
A Power or Ground signal for a component can be defined by placing the SIGNAL property on the symbol.
For example, for the following component...
...a symbol like the one below can be created (click to expand image):
There are two instances of the SIGNAL property: one for power (VCC;14) and one for ground (GND;7).
Typically symbols use Explicit Pins. Explicit pin setups are when the pins are be placed on the symbol. In such a case, the SIGNAL property is not used. Pins are placed with a repeating pin number in the pin table for each gate in the component to support gate swapping.
For example, for the following component...
...the following symbol can be created (click to expand image):
The power and ground (VCC+ and VCC-) are present on the symbol as pins, each with a repeating pin number.
Hiding Pin Numbers for Passives
To hide pin numbers, click on the pin in question, go to the Properties table for that part/pin, and delete the name.
Parts with many pins may be represented by a single symbol or by multiple symbols on a schematic. When multiple symbols are used to represent a single part, they are known as Fractured Symbols. The HETERO property is used to link the symbols and ensure correct packaging. Below are two examples of using the HETERO property for fractured symbols.
There 2 examples below:
- Gated part with gates represented by multiple and differing symbols.
- Large part with many pins broken up into multiple symbols.
Representing Gates with Different Symbols
To create the part below, two different symbols are used. The one on the far left is named MC74HC00ADTR2G (name field), followed by 3 instances of MC74HC00ADTR2Ga (name field) on the right.
Below are the above symbols displayed in the Symbol Editor. All properties must be identical with the exception of , since here the three instances of MC74HC00ADTR2Ga have been consolidated with a . Note that in this example, the property consists of the two symbol names, without extensions, separated by a comma, e.g. MC74HC00ADTR2G,MC74HC00ADTR2Ga. Pin numbers are split between the two symbols.
Representing a Large Part with Multiple Symbols
In the following example, it takes four symbols to represent a single part. Each of the 4 symbols are unique and all of them must be placed in the schematic. This is an example of a part with a large number of pins, like a microprocessor.
The properties must be identical for correct packaging. All symbols used to represent the part are listed in the HETERO property requires symbols surrounded by parentheses () to generate the correct netlist. The parentheses tell PADS Maker Schematic that all four symbols must be placed.property. In this case the
An example of a part with a large number of pins represented by multiple symbols is included in the Starter Library provided with PADS Maker. Please look under the IC Partition of the Parts window for Intel_mobilepiii-1, Intel_mobilepiii-2, Intel_mobilepiii-3, and Intel_mobilepiii-4. Note the use of the HETERO property. You will notice the symbols don't have a related footprint.
Click on the Maker_Enhanced_Library.pqz link. This file will extract and add Footprints associated to the symbol in the same way that PartQuest files are extracted.