Introduction to Digital Works

The Digital Works Window

Creating and using Macros

Converting the two-input multiplexer circuit into a black box

Creating the black box

• Left click on the arrow.• Right click on one of the macro tags.• Select Template Editor from the menu with

a left click.• The Template Editor window appears.

You can create a symbol for your circuit. There may already be a default black box and if there is you can use it if you like, or you can delete it and draw one that you like.

Creating a symbol for the new circuit

Procedure for building the macro

• Once you have drawn an object or decided to use the default one you select the Pin Icon by left clicking.

• You then place the cursor where you want it to be in the diagram and left click to insert it.

• Next select it and right click and select associate with tag from the menu.

• Next close the template editor. You will notice a 1 next to the selected macro tag.

• Now select another macro tag, right click and select template editor and repeat the above procedure except for drawing the template. Do this for the remaining macro tags and then save the file. You do not use a separate name for the macro.

Creating an interface point in the black box

The completed black box representation

The original circuit with the macro tags numbered

Using a Macro

Embedding a macro in a circuit

Using a Macro continued• You can use the push button interactive tool to

insert inputs to the macro and the LED tool to insert outputs to the macro. You then wire the interactive buttons and LEDs to the appropriate macro icons. You can then run and test it.

• Suppose you want to build a circuit having more than one macro (which may or may not be the same)

• Select the embed macro button and position the cursor to where you want it in the workspace and left click.

Embedding two macros, wiring them together

Editing a macro in a circuit

Editing the expanded form of the macro

Decimal CodesDecimal 8421 Excess-3

digit code code

0 0000 0011

1 0001 0100

2 0010 0101

3 0011 0110

4 0100 0111

5 0101 1000

6 0110 1001

7 0111 1010

8 1000 1011

9 1001 1100

Building a BCD adder

• Adding two single decimal digits given in 8421 BCD code can be accomplished by adding the 8421 representations as binary numbers. If there is no carry then the sum digit is exactly the binary sum and represents the 8421 representation of the two decimal digits. If there is a carry then this carry bit corresponds to 16 decimal and thus the correct two digit decimal number can be determined by subtracting 6 from the 5th bit making it a 10 and adding the 6 into the first digit which is represented by the rightmost 4 digits.

• For example a sum of 18, given as 1 0010 = 16 + 2. If we count the leading 1 as the tens digit then we must add 6 + 2 to get 10 + 8 = 18, i.e. 16 – 6 = 10 and 0010 + 0110 = 1000. Now the 1 0010 = 0001 1000 as a 8421 BCD 2 digit number.

Organization of a single-decade 8421 BCDdecimal adder.

Organization of a single-decade 8421 BCD adder.

Karnaugh map to detect the combinations P3P2P1P0 = 1010, 1011, . . . , 1111.

P3P2 + P3P1 true

implies one of theabove combinations

A single-decade 8421 BCD adder.