Truth Table
Represent logical decision-making behavior with conditions, decisions, and actions
Libraries:
Stateflow
Description
The Truth Table block represents combinatorial logic design in a tabular format. You can use truth table blocks to model decision making behavior based on a set of conditions. For more information, see Use Truth Tables to Model Combinatorial Logic.
To implement control logic, Truth Table blocks use MATLAB® as the action language.
Examples
Home Climate Control Using the Truth Table Block
Model a home climate control system by using a Truth Table block.
Ports
Input
Port_1 — Input port
scalar | vector | matrix
When you create input data in the Stateflow® truth table using the Symbols pane, Stateflow creates a corresponding input port on the Truth Table block.
Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated | bus | string
Output
Port_1 — Output port
scalar | vector | matrix
When you create output data in the Stateflow truth table by using the Symbols pane, Stateflow creates a corresponding output port on the Truth Table block.
Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated | bus | string
Parameters
To edit block parameters interactively, use the Property Inspector. From the Simulink® Toolstrip, on the Simulation tab, in the Prepare gallery, select Property Inspector.
Note
Truth Table blocks also have Subsystem (Simulink) block parameters that you can access by right-clicking the block and clicking Block Parameters (Subsystem). However, updating these block parameters is not recommended.
Update method — Method to update or wake up a Stateflow truth table
Inherited (default) | Discrete | Continuous
Method to update or wake up a Stateflow truth table, specified as
Inherited, Discrete,
or Continuous.
InheritedInput from the Simulink model determines when the truth table wakes up during a simulation (default).
If you define input events for the truth table, the Stateflow truth table is explicitly triggered by a signal on its trigger port originating from a connected Simulink block. You can set this trigger input event to occur in response to a Simulink signal. The Simulink signal can be
Rising,Falling, orEither(rising and falling), or in response to aFunction Call. For more information, see Activate a Stateflow Chart by Sending Input Events.If you do not define input events, the Stateflow truth table implicitly inherits triggers from the Stateflow model. These implicit events are the discrete or continuous sample times of the Stateflow signals providing inputs to the truth table. If you define data inputs, the truth table awakens at the rate of the fastest data input. If you do not define any data input for the truth table, the truth table wakes up as defined by the execution behavior of its parent subsystem.
DiscreteThe Simulink model generates an implicit event at regular time intervals to awaken the Stateflow truth table at the rate that you specify in the Sample Time truth table parameter. Other blocks in the Simulink model can have different sample times.
ContinuousThe Stateflow truth table updates its state during major time steps only, although it computes outputs and local continuous variables during major and minor time steps. For more information, see Continuous-Time Modeling in Stateflow.
Programmatic Use
To set the block parameter value programmatically, access the Stateflow.TruthTableChart object of the block and change
the object property by using dot notation.
| Parameter: | ChartUpdate |
| Values: | "INHERITED" (default) | "CONTINUOUS" | "DISCRETE" |
Sample time — Time interval that a Stateflow truth table wakes up during simulation
-1 (default) | scalar | vector
Time interval that a truth table wakes up during simulation, specified by
a scalar or a vector. The default time interval is -1,
which indicates that the Stateflow truth table inherits the sample time from Simulink.
Do not use the Sample Time parameter in the Subsystem block parameters. Instead, use the Property Inspector.
Dependencies
To enable this parameter, set Update method to
Discrete.
Programmatic Use
To set the block parameter value programmatically, access the Stateflow.TruthTableChart object of the block and change
the object property by using dot notation.
| Parameter: | SampleTime |
| Values: | "-1" (default) | string scalar | character vector |
| Data Types: | string | char |
Advanced
Saturate on integer overflow — Whether data saturates on integer
overflow
on (default) | off
Whether the data in the truth table saturates on integer overflow. When you clear this parameter, the data in the truth table wraps on integer overflow. For more information, see Handle Integer and Enumeration Overflow for Chart Data.
Programmatic Use
To set the block parameter value programmatically, access the
Stateflow.TruthTableChart object of the block and
change the object property by using dot notation.
| Parameter: | SaturateOnIntegerOverflow |
| Values: | true or
1 (default) | false or 0 |
| Data Types: | logical |
Support variable-size arrays — Whether the truth table supports variable size data
on (default) | off
Whether the truth table supports variable-size data. For more information, see Declare Variable-Size Data in Stateflow Charts.
Programmatic Use
To set the block parameter value programmatically, access the
Stateflow.TruthTableChart object of the block and
change the object property by using dot notation.
| Parameter: | SupportVariableSizing |
| Values: | true or
1 (default) | false or 0 |
| Data Types: | logical |
Treat dimensions of length 1 as fixed size — Whether truth table treats output data with dimension of length 1 as fixed size
on (default) | off
Since R2023a
Whether the truth table treats output data with a dimension of length 1 as fixed size. When you select this parameter, the truth table treats output data that have at least one dimension of length 1 as fixed size, regardless of whether you enable the Variable size data property. When you clear this parameter, the truth table treats data with the Variable size property enabled as variable size.
Programmatic Use
To set the block parameter value programmatically, access the
Stateflow.TruthTableChart object of the block and
change the object property by using dot notation.
| Parameter: | TreatDimensionOfLengthOneAsFixedSize |
| Values: | true or
1 (default) | false or 0 |
| Data Types: | logical |
Overspecification — Level of diagnostic when truth table is overspecified
"Error" (default) | "Warning" | "None"
Level of diagnostic action when the truth table is overspecified,
specified as "Error", "Warning",
or "None". For more information, see Correct Overspecified and Underspecified Truth Tables.
Programmatic Use
To set the block parameter value programmatically, access the
Stateflow.TruthTableChart object of the block and
change the object property by using dot notation.
| Parameter: | OverSpecDiagnostic |
| Values: | "Error" (default) | "Warning" | "None" |
Fixed-point properties
Treat these inherited Simulink signal types as fi objects — Inherited Simulink signals to treat as fi objects
Fixed-point (default) | Fixed-point & Integer
Inherited Simulink signals to treat as Fixed-Point Designer™
fi objects, specified as one of these values:
Fixed-point— The truth table treats all fixed-point inputs asfiobjects.Fixed-point & Integer— The truth table treats all fixed-point and integer inputs asfiobjects.
This parameter applies only to truth tables that use MATLAB as the action language.
Programmatic Use
To set the block parameter value programmatically, access the
Stateflow.TruthTableChart object of the block and
change the object property by using dot notation.
| Parameter: | TreatAsFi |
| Values: | "Fixed-point" (default) | "Fixed-point & Integer" |
MATLAB Chart fimath — Default fimath object properties
Same as MATLAB (default) | Specify Other
Default fimath object properties for the truth table,
specified as one of these values:
Same as MATLAB— The truth table uses the samefimathobject properties as the current defaultfimathobject. The text box is dimmed and displays the current globalfimathobject in read-only form.Specify other— Specify your ownfimathobject in the text box.
For more information, see fimath Object Construction (Fixed-Point Designer).
Programmatic Use
To set the block parameter value programmatically, access the
Stateflow.TruthTableChart object of the block and
change the object property by using dot notation.
| Parameter: | EmlDefaultFimath |
| Values: | "Same as MATLAB
Default" (default) | "Other:UserSpecified" |
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.
HDL Code Generation
Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.
HDL Coder™ provides additional configuration options that affect HDL implementation and synthesized logic.
You can use a tunable parameter in a Truth Table block intended for HDL code generation. For details, see Generate DUT Ports for Tunable Parameters (HDL Coder).
This block has one default HDL architecture.
| ConstMultiplierOptimization | Canonical signed digit (CSD) or factored CSD optimization. The
default is |
| ConstrainedOutputPipeline | Number of registers to place at
the outputs by moving existing delays within your design. Distributed
pipelining does not redistribute these registers. The default is
|
| DistributedPipelining | Pipeline register distribution,
or register retiming. The default is |
| InputPipeline | Number of input pipeline stages
to insert in the generated code. Distributed pipelining and constrained
output pipelining can move these registers. The default is
|
| OutputPipeline | Number of output pipeline stages
to insert in the generated code. Distributed pipelining and constrained
output pipelining can move these registers. The default is
|
| ResetType | Suppress reset logic generation. The default is |
| SharingFactor | Number of functionally equivalent resources to map to a single shared resource. The default is 0. See also Resource Sharing (HDL Coder). |
The block participates in these HDL optimizations to optimize the speed, and area.
Speed and Area Optimization
| Optimization | Description |
|---|---|
| Distributed Pipelining (HDL Coder) | Distributed pipelining, or register retiming, is a speed optimization that moves existing delays in a design to reduce the critical path while preserving functional behavior. |
| Resource Sharing (HDL Coder) | Resource sharing is an area optimization in which HDL Coder identifies multiple functionally equivalent resources and replaces them with a single resource. |
| Delay Balancing (HDL Coder) | When optimizations or block implementation options introduce delays along the critical path in a model, Delay Balancing detects introduction of new delays along one path, and then inserts matching delays on the other paths. |
| Clock-Rate Pipelining (HDL Coder) | Clock-rate pipelining is an optimization framework in HDL Coder that allows other speed and area optimizations to introduce latency at the clock rate. |
| Adaptive Pipelining (HDL Coder) | Adaptive pipelining optimization creates patterns or combination of blocks with registers that can improve the achievable clock frequency and reduce the area usage on the FPGA boards by inserting pipeline registers to the blocks in your design. |
| Critical Path Estimation (HDL Coder) | To quickly identify the most likely critical path in your design, use Critical Path Estimation. Critical path estimation speeds up the iterative process of finding the critical path. To know blocks that are characterized in critical path estimation, see Characterized Blocks (HDL Coder). |
To learn about restrictions, see Introduction to Stateflow HDL Code Generation (HDL Coder).
When you apply optimizations, the block has these limitations:
HDL optimizations are not supported for the block that has Trigger port.
PLC Code Generation
Generate Structured Text code using Simulink® PLC Coder™.
Fixed-Point Conversion
Design and simulate fixed-point systems using Fixed-Point Designer™.
Version History
Introduced before R2006aR2023a: Specify how to treat output data with dimension of length 1
With the new parameter Treat dimensions of length 1 as fixed size, you can specify how truth tables treat output data when at least one dimension has length 1. Prior to R2023a, truth tables treat output data with at least one dimension of length 1 as fixed size, regardless of whether you enable the Variable size data property.
See Also
Blocks
Objects
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