This is an input part and provides logic HI value. It is connected at
those places which require constant logic HI value.
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The word Track is borrowed from PCB (Printed Circuit Board) terminology which
is used to assemble a circuit. A Track is a printed wire on a circuit board
which is used to connect components through their pins. Track or wire is used
to connect components with each other to form a circuit. A circuit is a
collection of tracks and components. A Track plays the same role in this
software as it plays in a PCB. It is used to connect pins of various
components in the circuit.
How to Connect Two pins via Track or Wire
1.
Click the Track button in the Tool Bar in Operation Tools Box.
2.
Move to the drawing area. The cursor will change its shape to a Track drawing
and connecting tool (Solding Iron)
.
3.
Click the one of the pins you want to connect and move to the other pin. A
Track is start drawing as you move the mouse.
4.
Click the other pin you want to connect. A straight line or Track will be
drawn between the two pin. i.e., both pins are now connected via this Track or
wire.
Important Notes
1.
When you bring the Track drawing cursor to a pin or a Track/wire, the tool
may change its color from Yellow to Green
. It means that you are allowed to connect to this Pin or Track/wire. If it does not
change its color, you are not allowed to connect to that pin or Track/wire, because:
a.
You cannot connect two output pins to the same Track/wire. A Track/wire may connects
to a number of input pins but only to one output pin at a time.
b.
When a pin is connected to a Track/wire, you cannot directly make any new
connection to that pin but only to the track/wire connected to this pin. If you want
to a mber of pins, first connect any two pins through a Track/wire, then connect
all other pins to this Track/wire by drawing Track/wire between each Pin and the Track/wire.
Track Drawing and Editing
You may draw straight line Track/wire or you may draw segmented Track/wire.
During Track drawing if you left-click the mouse, the previous Track line will
stop there and a new Track line will start from this point onward. The click
point becomes the drag-point of the Track/wire to change its shape. In this
way you can draw Track of any shape composed of a number of straight line segments.
If you want to align the Track, Click the Ready button
in the "Operations" Tool Box in the Tool Bar and then click the Track. The Track
will show all the drag-able points as BLACK color boxes which you can use to
change the shape or alignment of the Track. Use the mouse for dragging or just
click the drag-able point, and it will change its color to RED, on the Track
and use arrow key to change the alignment of the Track.
It is recommended that instead of drawing long straight Track; draw the track
in a number of small segments, by clicking at various places along the path of
the Track to introduce drag-able points in the Track, which will be helpful to
adjust the shape and alignment of the Track at later stage of circuit design.
When a Track makes a connection with another Track, a BLACK box will appear at
the point of connection and if a Track just passes over another Track, no such
box will appear.
Component PIN Types
There are four different types of pins may be present in a Component:
Input Pins : Use to receive data from other components.
Output Pins : Use to send data out of the component to other component.
Control Pins : These are Input Pins but trigger special operation inside
the component
TRI-State Pins : These are Output Pins but they can be put in High
Impendence mode by EN pin. In this mode it is like cut-off from all other
components. All those components which have EN or output enable control pin,
their output pins become TRI-State pins.
Note : A Track/Wire may only be connected to one Output pin but can be
connected to any number of Input and TRI-State pins.
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After completing a circuit, you can run the simulation to check the working of
the circuit. In simulation mode you may change or enter values in your circuit
through input parts and observe the behavior of your circuit through output
parts or on a digital Oscilloscope provided in this software. There are three
buttons associated with the simulation of any circuit.
Run the simulation
Stop the simulation
Pause and Resume the simulation
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10 - How to use a Digital Scope
The Digital Oscilloscope or Scope provides the visual information regarding
signal level at different points in a circuit. The Scope works in combination
with the probe which marks the places where we monitor the signal level during
running of the circuit.
Step-by-Step
1.
Design the circuit or open an already designed circuit.
2.
Decide about the points where you want to monitor the signals in the circuit
during its operation.
3.
Now click the Probe icon
in the Scope tool box in the tool bar.
4.
Move to the drawing area. The cursor will change its shape to a Black circle
.
5.
Click the mouse near the place where you want to monitor the signal level. A
back Circle is placed at that place.
6.
Mark and place the probe at all the places in the same way.
7.
Now click the Track icon
in the "Operations" tool box in the tool bar and draw the track/wire between
the Probe marking and the monitoring places.
8.
Assign names to the Probe marking, by using each Probe drop-down menu.
9.
By using the drop-down menu of each Probe, assign the Id number to each Probe
marking according to the order in which you want them to appear in the Scope
display.
10.
Now click the Scope icon
in the "Scope" tool box in the tool bar.
11.
A new Scope Window will be opened showing all the signal names assigned to the
Probe marking and as per their assigned number value in ascending order.
12.
Now run the simulation.
13.
All the signal information will start displaying in the Scope window.
14.
You can save the scope data by selecting menu Data->Save Data.
15.
You can also view the already save data by selecting menu Data->View Saved Data.
16.
You can also set that at which value the scope Start recording the data, Stop
recording the data, and How many values it must record before stop recording
and displaying the signal information. These settings are available in the
Trigger menu of the scope window.
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11 - How to make a custom Modules or ICs (Integrated Circuits)
A circuit can easily be converted into reusable Module or IC which may be used to
build more complex circuits. They behave like ICs in a circuit.
How to convert a circuit into a Module
When a circuit is converted into a module/ic, all the Buttons and LEDs,
present in the circuit are replaced by input and output pins of the IC,
respectively. The name of these Buttons and LEDs becomes the name of the pin
while their Numbers become the pin number which determines the position of
the pin in the image of the newly created IC.
Step-by-Step:
1.
Design the circuit for the Module.
2.
Place and connect Button on all the places which will appear as input pins of the IC.
3.
Place and connect LEDs on all the places which will appear as Output pins of the IC.
4.
Assign at most three characters long name to each of these Buttons and LEDs
using respective drop-down menu.
5.
Assign Number to these Button and LED according to their placement on the Module
image, using drop-down menu.
6.
If you want to place a Not Connected or NC pin, just place a Button or LED in
the circuit diagram but do not connect it to any other Track or pin. Assign it
the name NC and also a pin number using drop-down menu.
7.
Now select menu File->Convert To IC and select the name and folder for the
newly generated IC. The new IC will be generated.
8.
All the Modules/ICs which are placed in DLD/Module folder will appear in Module
menu of the program.
9.
The Modules which are stored in any other folder can be access using "Other"
Load option in ICs menu bar.
A module can be used as many times as needed in a circuit. All such instances
of a module behave as standalone and separate parts. Any modification in one
instance of a module does not affect any other instance of same module/IC and,
therefore, later changes in the module design will not affect the already used
instances of such module, until and unless, manually replaced with the modified
module.
Suggestions
The following suggestions are not bindings but useful for designing better
reusable ICs.
If there is a Clock component in the circuit, replace it with a Button and
provide Clock signals externally to the Module/IC.
Remove / replace all other Input/output parts (except Buttons and LEDs) from
the circuit as they serve no useful purpose in a module.
When making such changes, always modify a copy of that circuit file and not
the original circuit diagram.
If there is some component already available in the software, like flip-flops,
use these parts instead of designing new module for same functionality.
Adding Description in Module
The Designer name and Module Description appears in the context menu About
of the Module. If the module uses any other module, the name of the Designer
of that Module will also be shown. The Description is added by introducing
a Text field, named D into the circuit diagram of the Module.
Step-by-Step:
1.
Insert a Text field into the circuit diagram and enter the Description into it.
2.
Right-click this Text field and assign the Text field Title as H
3.
This Text field can be placed anywhere on the circuit diagram.
4.
Save the circuit and generate the Module/IC.
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13 - How to make a State Machine
It is a component whose next output value (state) depends upon it current input value
(state) and on its current output value (state).
(Current_Input, Current_Output) -> Next_Output.
User must provide a text data file having .smd extension.
This file may be placed in /Data folder under the application folder.
The data is provided in the following format in this file:
<Input_Value><Space><Output_Value>><Space><Next_Output_Value>
..
..
..
END
Input value, output values and next output values are integer values separated
by single space. If clr/Clear or Reset pins are available, the first Output_Value
in the file is treated as reset or clear value.
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14 - Generating ICs from Boolean Expressions
User can also generate a custom component / IC by providing Boolean expressions
for the required custom components / IC. The Boolean expression is provided in
Sum-or-Product (SOP) form for each output pin of the component.
User must provide Boolean Expression(s) in a data file. This file may be
placed in /Data folder under the application folder. This is a simple text file
having .exp extension. The format of the file is given below:
<Name_of_The_Component>
<Number_of_Input_Pins><Space><Number_of_Output_Pins>
<Name_of_Input_Pins_Separated_by_Space>
<Name_of_Output_Pins_Separated_by_Space>
<Minterms_of_Boolean_Expression_Separated_By_Space_for_Output_Pin_0>
<Minterms_of_Boolean_Expression_Separated_By_Space_for_Output_Pin_1>
<Minterms_of_Boolean_Expression_Separated_By_Space_for_Output_Pin_n>
END
Minterm are provided in decimal form separated by single spaces. The Boolean
Expression in the form of Minterms will be provided for each output pin in
ascending order on separate line. Pin names may be three characters long which
may include the pin number if the designer does so. The input and output pin
quantity, i.e., number of input pins and number of output pins, are provided
as integer values separated by space. Name of the component should be a single
word name.
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15 - Adding Control Pins in ICs
Control pins add special features in a component. Control Pins can be added
and removed from an IC/Module through it context or drop down menu under
Control Pins option by selection and deselecting the relevant checkbox. The
active value for these pins also set in the same menu.
The types and purpose of three common control pins are given below:
EN Output enable pin. It is used to enable or disable output of a
component. When output is disabled, the component output goes into
high-impedance (Z) mode.
CS Chip select pin. It is use to select or deselect a component. If a
component CS id disable, the component perform no operation.
clk Clock pin. The purpose of this pin is to synchronize a component
operation with other components. In Counter components it is used to increment
or decrement a counter. A counter already has clk pin which is RE or rising-edge
active.
There are some special control pins specific to different components as given
below:
clr Clear or reset pin which is active HI. In Counters, it reset counter
value to 0.
DN Down-counting pin which is active HI and it is available for Counter
components to enable down counting of each clock pulse.
LD Load Counter pin. It is used with Counters and Registers to directly
load some data into the component. It is usually set as active on RE or FE.
SF Shift control pin adds data shift property in the Register.
DR Direction control pin determines the direction of data shift as
left shift or right shift in a Register.
Every control pin can be set active on any of the following
signal values:
HI High value, 1.
LO Low value, 0.
RE Rising Edge, when value is changing from LO to HI.
FE Falling edge, when value is changing from HI to LO.
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The user must provide the length of a word in Bits as Data size and also the
size of the memory in number of locations. These locations are accessed through
address pins whose name starts with A followed by the pin number. The
data appears on output pins whose name starts with O followed by pin number.
Data can also be load into the memory. The file may be placed in /Data folder.
This is a simple text file having .mem extension. The format of the file is given
below:
<Memory_Location><Space><Data_Value>>
..
..
..
END
Memory Location and Data value integer values separated by single space.
Memory Read Cycle
1.
CS->LO , RW->LO Set CS and RW control line to LO, i.e., their de-active value
2.
Set Memory address
3.
CS->HI, EN->HI Set CS and EN control line to HI, i.e., their active value
4.
CS->LO
Data from the given address will be appear on output pins
Memory Write Cycle
1.
CS->LO
2.
Set Memory Address
3.
Set Data on Data Line through TRI State Gate
4.
RW->HI, CS->HI Set CS and RW control line to LO, i.e., their active value
5.
CS->LO
Data will be written in the given location
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12 - Components Parameters
Component Menu
provide a list of all available standard parts or component, other than that
available in the Tool Bar, which can be customized and used for the circuit
designing.
A component may
have a number of parameters, like name and id number, which may be set by using
component context or drop down menu in a circuit drawing. This menu appears
when a component is right-clicked with the mouse. Components may have different
parameters depending upon their type. Some components have more parameters
which may be set while some has less. Some parameters like name and id are
common for all the components while some are available for specific components.
This section provides the details regarding parameters of components which may
be set by the user.
There are three
common parameters for each component:
NameIt is single word
meaningful Name of the Component assigned by the designer. It is optional but
required for Probe, Button and LED component.
NumberIt is an integer number,
starting from 1, assigned to a component. It is a good practice to use unique
numbers for every component or at least the number should not be repeated for
same type of components. It is optional for most of the components but required
for Probe, Button and LED component. When converting a circuit into a Module,
it is strongly recommended that Button and LED should be assigned unique
numbers in ascending order according to their pin position in the newly created
Module.
TpdPropagation delay.
This value is option for all the components and only set when some critical
timing analysis of a circuit is required. It is needed for very advance level
design. A propagation delay of 1 equals to one clock cycle, i.e., the value of
5 means a propagation delay of 5 clock cycles. It is an advance concept and
should used with lot of care. Normally components have no propagation delay in
this software.
There are three more parameters specific to
components:
Control
PinsYou can add or remove control pins in a component. The control
pins are discussed in a separate section.
Properties
It varies from one type of component to other. It is used to set
number of input and output pins or size of value in bits according to the
component type.
Load
It is used to load some data into the component. This
feature is discussed in relevant component section.
The parameters
specific to components are discussed below with relevant components:
Adder
Properties: User is required to set the size
of the operands, in Bits, which are going to be added. A size of 4 means, there
will be two operands of 4 bits each and the result is also of 4 bits long.
Operands are represented by pins whose name started with a and b
while output pins have name stated with O. (O = a + b). The overflow
or Carry pin C is HI when there is some carry.
Subtractor
Properties:
User is required to set the size of the operands, in Bits, which are
going to be subtracted. A size of 4 means, there will be two operands of 4 bits
each and the result is also of 4 bits long. Operands are represented by pins
whose name started with a and b while output pins have name
stated with O. (O = a b). The sign bit s represent the
sign. If b > a then sign bit is set HI and remaining output pins show
the magnitude.
Comparator
Properties:
User is required to set the size of the operands, in Bits, which are
going to be compared. A size of 4 means, there will be two operands of 4 bits
each and the result is of 3 bits long. Operands are represented by pins whose
name started with a and b while output pins have name stated
with O. The result of comparison is shown by the HI value on
output pin named as a > b, a=b and a<b for
respective result.
Converter
Properties: User is
required to set the number of input and output pins.
Load:
A user must provide a data file to provide conversion value.
This file may be placed in /Data folder under the application folder. This is a
simple text file having .con extension.� The format of the file is given
below:
<Input_Value><Space><Output_Value>
..
..
END
Input
value and output values are integer values separated by single space.
Encoder
Properties: User is required to set the number
of input pin.
Decoder
Properties: User is required to set the number
of input pin.
Mux
Properties:
User is required to set the size of an input Chanel, in Bits, and also
set the number of channels required in the Multiplexer. A channel represents a
value or operand. Input channels are represented by pins whose names are
started with A, B, C followed by pin number. The output
channel pins names are started with O followed by pin number. The
channel selection pins names are started with s.
DeMux
Properties:
User is required to set the size of an output Chanel, in Bits, and also
set the number of channels required in the Multiplexer. A channel represents a
value or operand. Output channels are represented by pins whose names are
started with A, B, C followed by pin number. The channel
selection pins names are started with s. The input channel pins names
are started with i followed by the pin number.
Counter
Properties: User is required to provide the
size of the counter in Bits.
CounterLoader
Data is provided on the data input pins, whose name started with D
followed by the pin number, to be loaded into the counter.
Properties: User is
required to provide the size of the counter in Bits.
CounterRandom
Properties: User is
required to provide the size of the counter in Bits.
Load:
A user must provide a data file to provide random values in
the same order as may be appear on the counter output. This file may be placed
in /Data folder under the application folder. This is a simple text file having
.crd extension.� The format of the file is given below:
<Random_Value>
..
..
END
Random value is an integer value.
Register
Properties: User is required to provide the
size of the Register in Bits.
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AND
OR
NOT
TRI
NAND
NOR
XOR
XNOR
SR
JK
D
T
