SinelaboreRT

anonymous@undisclosed.example.com (Anonymous) — Sat, 18 Dec 2021 10:45:15 +0000

List of previous announcements and news

Latest News

anonymous@undisclosed.example.com (Anonymous) — Sun, 15 Mar 2026 19:22:24 +0000

Latest News

March 2026 | New version 7.1

Update for SysMLV2. This version improves the code generation and adds more supported SysMLV2 features. E.g. actions are SysMLV2 first hand features and as such represented as structs in the generated code and not as methods anymore. Checkout the GitHub examples for more details.

November 2025 | New version 7.0

SysML v2 is here — and it’s announced as major leap forward in systems modeling. I've taken a first deep dive into the new modelling language, exploring its strengths, potential, and some early tooling support. The latest version 7.0 supports the generation of CPPX code from a SysML v2 textual model. With the help of a small framework the generated parts and state-machine code can be easily be executed and tested.

July 2025 | SysML v2.0 - First Experiments

We explored the current status of SysML v2. Read more in this article.

February 2025 | New version 6.5.2

This new version is recommended to all users. Core modules were refactored for better maintainability and consistency and improved test coverage. Improved CPPX code generation to eliminate unnecessary dynamic memory allocations.

February 2025 | New version 6.5.1

Beside several improvements support for additional command-line parameters when using ’-l cppx’ was added. You can now optionally specify -std with additional information to enable all necessary parameters for the corresponding language features either for either version 11 or 14. This simplifies configuration for new users. For more details, see section “Generating CPP Code”.

September 2024 | New version 6.4

Since version 6.4 the handling of history states has been changed. It is now possible to end a transition in a history state. Only if a transition ends in a history state will the previous history be taken into account when entering the state set. Otherwise the default entry chain is used. The new parameter TransitionsCanEndInHistoryStates has been added to enable this feature. This new feature makes history state handling more powerful and the designer's intent clearer than before. An example of the new possibilities is shown in the following figure.

August 2024 | New version 6.3.4

This release adds another way to influence the signature of the processEvent() method in C++.

June 2024 | New version 6.3.3

This version provides some small updates for the Python backend and fixes an issue with the C Sharp backend.

18. Feb. 2024 | New version 6.3.2.1

Bugfix in the C++ backend. Relevant for users who have state machines with regions and do not want event handler parameters. With previous version a msg parameter of the region code was generated. In the previous version, a msg parameter was incorrectly generated for the region handler code. This has now been corrected.

18. Feb. 2024 | New version 6.3.2

A state machine with regions can be in more than one state at a time. Previously the getInnermostActiveState() function only returned the topmost state the state machine was in. With this release, some backends can return more states to reflect the real situation.

Improvements in the JS backend. IsIn() and getInnermostActiveStates() works now with regions.
Improvements in the C++11 backend. IsIn() and getInnermostActiveStates() works now with regions (cpp-11 only).

In the case of C++11, the generated function has this signature:

auto oven::getInnermostActiveStates() const -> std::forward_list<oven::States>{
  std::forward_list<oven::States> stateList;
  ...
  return stateList;
}

22. Jan. 2024 | New version 6.3

JavaScript is now supported as new target language for the code generator

20. Nov. 2023 | New version 6.2

Go is now supported as new target language for the code generator

26. Sep. 2023 | New version 6.1

Changes:

Bugfixes and improvements in the built in state-diagram editor
Use of a project specific configuration file in the graphical editor
New C-backend related parameters to generate code following the opaque object pattern (https://en.wikipedia.org/wiki/Opaque_pointer) to hide the state machine implementation from other user code and thereof reduce dependencies.
Improvements in the section about the c-backend and reorganization of the examples folder in the download.

New features:

Experimental parsing for the DrawIO Editor added
Events marked external are now exported in a separate file to allow further external processing. This allows to generate one file containing all state machine events (only with events as defines possible). Designs with a global event bus where all machines always receive all events could benefit from this feature.

12. Aug. 2023 | New version 6.0.5

Experimental support for DrawIO added

29. July 2023 | New version 6.0.4

Small bug-fixes and several improvements in the built-in graphical state diagram editor.

5. July 2023 | New version 6.0.3

Only available as jar download. Small bug-fixes in the built-in graphical state diagram editor as well as small improvements in the C-backend. It is better taking care of C89 only compilers.

3. June 2023 | New version 6.0.2

Several minor improvements especially for the cbackend. With some new configuration parameters, the generated code now passes the clang-tidy checks for c++11 with ''modernise-'' checks enabled. A new example has been added to the examples folder to show how to set the parameters in a sensible way. === 1. March 2023 New version 6.0 === This major release fixes many small issues and adds support for generating code from Eclipse Papyrus™. There is a step by step introduction video available. === 27. Jan 2023 | New version 5.5.6.3515 === This version fixes a bug in handling config files. Recommended for all users. === 21. Jan 2023 | New version 5.5.6.3490 === This version adds many small improvements to the integrated state diagram editor. * Code editor window is not always on top * A larger font in the state diagram used by default. The size can be configured in the configuration file. * Improved layout (larger distance between states) to increase readably of transition texts * The configuration file is now searched locally and then in the users home directory. If the location was given as command line it has always priority. * Display of an error symbol in correct line of the output window in the case when the model check returns an error. * Some IDEs do treat files ending in cfg in a special way. Therefore the codegen configuration file can also be named codegen.cf optionally. * Many more … === Dec 2022 | New version 5.5.5.5 === This new version adds Rust as a language backend. === June 2022 | New version 5.5.5.1 === This new version fixed several issues related to misra 2012 rules. As a result also some recommended parameter settings are published here to get you started. Recommended for all C/C users.

May 2022 | New version 5.5.5

This new version improved region handling for own instance data types. Recommended update for all C backend users. Additionally it improves XMI parsing of attributes and methods for the various supported UML tools.

January 2022 | New version 5.5.4

This new version brings Ctemplate parameters to the event handler method. As well as the option to hand over a user defined parameter to the event handler method in C#. Both increases flexibility to hand over data together with the event to the state machine. === January 2022 New version 5.5.2 === This new version allows to add attributes and operations to EA/UModel class diagrams. They are added to the generated code. An example about the creation of signal forming function blocks shows the new possibilities in detail. For users of the built-in state machine editor and the C-backend a new dialog shows all the configuration parameters and how they influence the signature of the generated state machine handler. === October 2021 | New version 5.4.1 === New Windows/Mac installer (thanks to Java 17) makes life easier for users who are not at ease with the command line. C backend now supports the ValidationCall parameter.

August 2021 | New version 5.3

Several usability improvements, bug fixes and new functions esp. in the built-in editor. Recommended for all users. A detailed change log is available in the Codegen Manual.

Jan.2021 | New version 5.2

. Complete rewritten built-in editor. Generate state diagram within minutes. Editor has full support for regions.

15.02.2020 | New version 4.1

This new version provides a backend for Lua. It is the first state machine code generator from UML state diagrams/machines to Lua. Lua is a lightweight, embeddable scripting language. It follows the approach described by Roberto Ierusalimschy in his book. More information is available here.

17.6.2019 | New version 3.7.4

This is a bug-fix version and recommended for all users. For users of the Cadifra tool connection points were added to keep oversight in complex diagrams more easy. Connection points are a well known concept in circuit diagram drawing tools. More details can be found in the sinelabore manual (Cadifra part).

2.5.2019 | New example for PIC users

This tutorial explains the use of state machines with the PIC16F18446 Curiosity Nano board. Go on reading ...

29.12.2017 | Sparx new EA Version

Tests of new EA version 13 were successful. If you find any flaws using the codegen with the new version send a bug report please.

20.9.2017 | QuickStart tutorial on how to use the code generator with Energia on GitHub

Energia is based on the Arduino IDE and is a great IDE for processors form Texas Instruments. The new example on GitHub shows the integration of code generated from the sinelabore code generator into the Energia IDE. What does the demo do: The flash frequency of the green LED on the MSP430FR5969 LaunchPad can be controlled. A minimal timer and queueing lib is used as basis to be prepared for much more challenging tasks. You will see the benefit of state machine modeling over direct coding. Take a look at the state diagrams and the generated code here! Or download the example and try it out yourself.

9.4.2017 | New version 3.7.1 with some small improvements

Recommended for all C# users and those who use the built in editor/simulator.

6.11.2016 | Code Generator Features for High-Availability and Safety Systems

There is a new article in the “Designers Toolbox” explaining the special features for for High-Availability and Safety Systems offered from the C-backend.

16.10.2016 | Generate Python Code from State Diagrams

With version 3.7 is is now possible to generate Python code. The state machine code is generated as a Python class. All relevant state machine features are available. Look into the manual for details. The fully working microwave oven code is available in the examples folder. It contains a TKinter GUI wich makes simulation and testing of the generated state machine even simpler.

Interesting readings

anonymous@undisclosed.example.com (Anonymous) — Sun, 16 Jul 2023 09:54:33 +0000

Interesting readings

On this page you find interesting resources that might help you to become a better embedded software engineer.

Send us links to interesting material if you think it should appear here.

Books

Practical Model-Based Testing: A Tools Approach from Mark Utting and Bruno Legeard. Chapter 5 discusses “Testing from finite state machines”. 

“Test-Driven Development for Embedded C” from James W. Grenning. It teaches you how to use the unit testing frameworks Unity and CppUTest to test embedded software. This book does not explicitly discuss state machine testing.

“Constructing the User Interface with Statecharts” by Ian Horrocks was published 1999. But still gives very good introductions how to use state machine for designing user interfaces. Using concrete and extensively discussed examples, such as a CD player, he shows how to practically design GUIs with statecharts. Due to the chosen examples it is specifically useful for UI designers of real physical devices.

—-

Reports where state-machines are used in practise

NASA: Read this interesting article on “UML Statechart Autocoding for the Mars Science Lab (MSL) Mission”. This article describes how NASA generates flight code automatically from a state machine diagram. The generated code has been part of Curiosity’s flight software since launch, and continues to run onboard today. They describe how their generated code looks like and shares the lessons they learned. Link to the article.

Tools

SocketCAN is a CAN driver directly integrated into the Linux kernel. The SocketCAN concept extends the Berkeley sockets API in Linux by introducing a new protocol family, PF_CAN, that coexists with other protocol families, such as PF_INET for the Internet Protocol. That means you can work with CAN just using your TCP/IP know-how and related tools e.g. logging traffic with wireshark. More information is available at SocketCAN. A nice hardware interface for SocketCAN is candleLight.

Navigation

anonymous@undisclosed.example.com (Anonymous) — Sun, 15 Mar 2026 19:12:18 +0000

Modelling-Tool specific Intro

Generating CPP Code from SysML V2 textual models New!

Language Backends

RTOS/Bare Metal

How-To

Designers Toolbox

Using time triggered events
Using regions or not
High-Availability and Safety Systems
Model-based testing of state machines I
Model-based testing of state machines II
Create nice looking state flow diagrams using Mscgen
Article on www.embedded.com State charts can provide you with software quality insurance.
Tutorial about state machines@bela.io New!

Examples

There are better ways to model state machines than using spread sheets!

In the past different μC manufacturers have published application notes about the benefit of using state machines for the design of embedded software. An example is the application note SLAA402 from Texas Instruments (TI). It suggests to generate source code based on a spread sheet table. Nowadays several affordable UML modeling tools are available supporting the efficient design of state machines in a graphical way. SinelaboreRT generates production quality source code from state diagrams created with many different UML tools. Give it a try!

Latest Changes

From design to code with ease

anonymous@undisclosed.example.com (Anonymous) — Sat, 29 Nov 2025 13:08:46 +0000

From design to code with ease

Generate production ready source code from state diagrams

Sinelabore enables developers to effectively combine event-driven architecture, hierarchical state machines, model-based design and automatic code generation. A payback is usually given already immediately.

Generate CPP code from SysML V2 textual models

Sinelabore allows also the generation of CPP code on the basis of a SysML V2 textual specification. Code generation for parts, attributes, ports, enums, connections and of course state machines is supported. This allows to specify complete systems in a simple and efficient way and to simulate them on CPP basis. Some basic framework classes are used in addition to provide required glue code.

If you are specifically interested in the new SysML V2 features go on reading here.

What can Sinelabore do for me as an embedded software developer?

SinelaboreRT focus is on generation of readable and maintainable code from flat or hierarchical UML state machine diagrams. With its unique features the tool covers perfectly the requirements of embedded real-time and low-power application developers coding in C / CPP or another language. The generated code is independent of CPU and operating system.

What can Sinelabore do for me as a software developer for the IoT or for critical applications?

Many systems are likely candidates for implementation as finite state machines. A system that must sequence a series of actions or that must handle inputs differently depending on the mode it is in is often best implemented as a finite state machine. Typical examples are control-logic-oriented applications such as metering, monitoring, workflows and control applications. For IoT applications where parts of the application are implemented in Java / Python / C# / Lua / Rust / JavaScript / Go or Swift, the code can also be generated in these languages besides C or CPP.

How do I use the Code-Generator?

Use your existing favourite modelling tool and generate code from your created model with an easy-to-use command line tool. Or use the built editor to create state machines within minutes. Automatic model checks warn from design flaws. Configure the generation process according to your needs. Simulate your model. Generate trace code automatically if needed. All major state diagram features like hierarchical states, regions, history, sub-machines … are supported.

Download & Try it! There are examples for various UML modelling tools and target languages for having a quick start.

Does the Code Generator run on my OS?

The Sinelabore code generator runs on any OS that supports a modern Java Version e.g. Windows, Linux, macOS or from within a container.

Can I use the generated code on my embedded platform?

By generating code that can be compiled with virtually any compiler, and the ability to integrate with your existing IDE, build process or continuous integration system, the code generator can be quickly integrated into any project. Configuration is stored in a plain text file which allows customisation of generated code to exactly your needs.

Generated code has production-quality. It is based on nested switch/case and if/then/else statements. It is easy to read, understand and debug if needed. The generated code requires no compiler specific tricks except standard language features. This means that if the worst comes to the worst, you can easily change or expand the code by hand.
Can be used with any 8-, 16- or 32-bit CPUs. There is no run-time environment needed like with some other solutions.
Fits well in different system designs. The code generator does not dictate how you design your system. Therefore it is no problem to use the generated code in the context of a real-time operating system (VxWorks, FreeRTOS, embOS, RTEMS, …) or within an interrupt service routine or in a foreground / background (super loop) system.
There will be no problems when using static code analyzers.
Generated cpp code passes clang-tidy and is cpp11 ready (modernize-*). Set configuration parameters accordingly.

How Sinelabore Improves Developer Productivity

Avoid bugs that can waste countless hours of developer and end-user time before they are found. Developers spend a lot of their time coding state machines by hand. And have to do it whenever the design changes. Sinelabore avoids the error-prone and tedious hand-coding by generating high-quality source code directly from the state machine design document.

No gap between design and code anymore. The documentation is always up to date.
Use the UML tool of your choice: Cadifra UML Editor, UModel, Magic Draw, Enterprise Architect, Astah* / astah SysML, Visual Paradigm, Modelio
An integrated state diagram editor makes it easy to get started and allows you to create state diagrams within minutes. The entry barrier is significantly lower compared to full-fledged UML tools. A series of tutorials (see sidebar) explains step by step how to use the integrated diagram tool.
Use the code generator only for those parts of your software that benefit from state machine modeling and code generation. Use your existing development environment for all the other code. The code-generator does not dictate an “all or nothing” approach as many other commercial tools.
Automatic robustness tests, test-case generation, tracing and simulation
Extensive Manual with getting started section

Secure, On-site Code Generation

The code generator runs locally on your developer workstations, build servers or continuous integration servers. It does not use an internet connection and will never collect nor submit data, code, statistics, analytics, or any other information from your system over any channel.

Generate code in the shortest time

To get an impression of the powerful capabilities of the tool download the demo version. Checkout the examples folder to see the generated code. Follow the “Getting Started” pages on this website. The manual contains a basic introduction into state-machines in case you need a refresh. Read the sections related to your UML tool and the language backend you want to use. If no UML tool is already in place take a look at the built in state machine diagram editor.

To run the code you have two options.

Run the examples on your PC. The example folder contains examples for all supported modelling tools and various languages (C, CPP, …). The examples realizes a microwave oven and can be executed and tested. Play with the model and enhance it. Regenerate the code and learn from the warning and error messages.
Run examples on a Micro-Controller e.g. a MSP430 evaluation board using Energia. An example with all details is available on github.

Customers and what customers say

Sinelabore Code Generator is used worldwide by companies of all sizes, from well-known multinational organizations to smaller independent companies and consultants. The code generator is also used in a wide range of industries.

“Sinelabore has helped me implement the behavior of a complex, asynchronous system. All the UML 2 elements I needed are available. I like that I don’t have to draw the state machine, then separately implement it and keep these two synchronized; this saves me time and reduces the potential of bugs. The error checking to make sure the state machine is valid is also useful. —- Daniel Bedrenko / Software Developer @ BPS…tec GmbH”

“Thank you again for providing such great tool!”

“… wir nutzen Ihr Produkt schon seit vielen Jahren und es hat sich als zuverlässiges und wertvolles Werkzeug erwiesen …”

“We like Your Tool, infact we will give intro for another local company next week.”

Study done by “Laboratory of Model Driven Engineering for Embedded Systems @ CEA in France” with the title “Complete Code Generation from UML State Machine” write in their report “ … without optimization, Sinelabore generates the smallest executable size ,,,”.

Using State-Machines in (Low-Power) Embedded Systems

Reactive systems are characterized by a continuous interaction with their environment. They typically continuously receive inputs (events) from their environment and − usually within quite a short delay − react on these inputs. Reactive systems can be very well described with the help of state machines. State machines allow to develop an application in an iterative way. States in the state diagram often correspond to states in the application. The resulting model helps to manage the complexity of the application and to discuss it with colleagues from other departments (and domains). Details can be added step by step during the development. Even during creation, the Code Generator can check the state diagrams for consistency (Model Check). Its logic can be simulated and tested. This ensures that the state machine behaves as intended. State machines are very useful for control-oriented applications where attributes such as reliability, code size, power consumption, and real-time behavior are particularly important.

System Architecture

There are different ways how to integrate state machines in a specific system design. Some design principles are more applicable for developers of deeply embedded systems. Others more relevant for developers having not so tight resource constraints.

The SinelaboreRT code generator supports you in the creation of the state based control logic. Generated code fits well in different system designs. The code generator does not dictate how you design your system. Therefore it is no problem to use the generated code in the context of a real-time operating system or within an interrupt service routine or in a foreground / background system.

Using state machines in a main-loop

In this design an endless loop — typically the main function — calls one or more state machines after each other. It is still one of the most common ways of designing small embedded systems. The event information processed from the state machines might come from global or local variables fed from other code or IRQ handlers. The benefits of this design are no need for a runtime framework and only little RAM requirements.

The consequences are:

All housekeeping code has to be provided by the designer
Main loop must be fast enough for the overall required response time
In case of extensions the timing must be carefully rechecked again

Example:

void main(void){
  …
  sm_A();
  sm_B();
  …
}

Using state machines in a main loop with event queue

This design is like the one presented above. But the state machine receives its events from an event queue. The queue is filled from timer events, other state machines (cooperating machines) or interrupt handlers.

Benefits:

Events are not lost (queuing)
Event order is preserved
Decoupling of event processing from event generation.

Consequences:

A minimal runtime framework is required: Timers and Queues
Main loop must be fast enough for the overall required response time

A minimal runtime framework for C is available here: https://github.com/sinelabore/examples/tree/master/lib

It offers timers and queues. The intended usage is as follows:

Each state machine has an own event queue
Eventually a state machine requires one or more timers (single shot or cyclically).
A state machine can create as many timers as needed. When creating a timer the event queue of the state machine and the timeout event has to be provided. For different timers it makes sense to provide different timeout events.
To make the timer work, a tick counter variable has to be incremented cyclically from a timer interrupt (e.g., every 10 ms). The tick frequency should be selected based on the minimal required resolution of the timeout times.
A tick() function must be called in the main loop to check if any timer has expired. In case a timeout has happened the provided event is stored in the event queue of the state machine.
The main loop has to check if events are stored for a state machine in its queue. If there are new events they are pulled from the queue and the state machine is called with the event.

Example code with two state machines shows the general principle:

// tick irq
void tick(void){
  pulseCnt++;
}
 
 
void main(void){
  ….
 
  // create two queues for two state machines and init the timer subsystem
  fifoInit(&fifo2VendingMachine, fifo2VendingMachineRawMem, 8);
  fifoInit(&fifo2ProductStoreMachine, fifo2ProductStoreMachineRawMem, 8);
  timerInit();
 
  …
 
  while (1) {
    uint8_t evt;
    //
    // Check if there are new events for the state machine. If yes,
    // call state machine with event.
    //
    bool fifoEmpty = fifoIsEmpty(&fifo2VendingMachine);
    if (!fifoEmpty) {
      fifoGet(&fifo2VendingMachine, &evt);
      vending_machine(&vendingMachine, evt);
    }
 
    fifoEmpty = fifoIsEmpty(&fifo2ProductStoreMachine);
    if (!fifoEmpty) {
      fifoGet(&fifo2ProductStoreMachine, &evt);
      product_store_sm(&productStoreMachine, evt);
    }
 
   // any new timeouts?
   tick();
  }

As indicated in the figure above also other state machines or interrupt handlers might push events to the queue of a state machine. An example how to do this is shown below.

// add event evErr to a state machine queue.
void ISR_Btn1() {
  fifoPut(&fifo2VendingMachine, evErr);
}

Using state machines in a main loop with event queue, optimized for low power consumption

In low power system designs a key design goal is to keep the processor as long as possible in low power mode and only wake it up if something needs to be processed. The design is very similar to the one described above. The main difference is that the main loop runs not all time but only in case an event has happened. The timer service for the small runtime framework is handled in the timer interrupt.

A skeleton for the MSP430 looks as follows:

void main(void){
 
  // init system
 
  while(1) {
 
    // check event queues and run the state machine as shown above
 
     …
     __bis_SR_register(LPM3_bits + GIE);  // Enter low power mode once
     __no_operation();                    // no more events to process
   }
}
 
// Timer A0 interrupt service routine. If the timer 
// function tick() returns true there
// is a timeout and we wakeup the main loop.
#pragma vector=TIMER0_A0_VECTOR
__interrupt void Timer_A0(void)
{
  bool retVal=false;
 
  P1OUT |= BIT0; // toggle for debugging
 
  retVal = tick();
 
  if(retVal){
    // at least one timeout timer fired.
    // wake up main loop
    bic_SR_register_on_exit(LPM3_bits);
  }
  P1OUT &= ~BIT0; // toggle for debugging
  // no more events must be processed
}

The following temperature transmitter using a MSP430F1232 header board with just 256 bytes of RAM and 8K of program memory is based on this design principle. For more information on how to use state-machines in low-power embedded systems see here and here.

Using state machines in interrupts

Sometimes state dependent interrupt handling is required. Then it is useful to embed the state machine directly into the interrupt handler to save every us. Typical usage might be the pre-processing of characters received by a serial interface. Or state dependent filtering of an analog signal before further processing takes place. Using state machines in an interrupt handler can be useful in any system design.

For code generation some considerations are necessary. Usually it is necessary to decorate interrupt handlers with compiler specific keywords or vector information , etc. Furthermore interrupt service handlers have no parameters and no return value. To meet these requirements the Sinelabore code generator offers the parameters StateMachineFunctionPrefixHeader, StateMachineFunctionPrefixCFile and HsmFunctionWithInstanceParameters.

The example below shows an interrupt service routine with the compiler specific extensions as required by mspgcc

// generated state machine code for an irq
 
interrupt (INTERRUPT_VECTOR) IntServiceRoutine(void)
{
   /* generated statemachine code goes here */
}

To generate this code, set the key/value pairs in your configuration file the following way:

StateMachineFunctionPrefixCFile=interrupt (INTERRUPT_VECTOR)
HsmFunctionWithInstanceParameters=no

If the prefix of the interrupt service routine requires to span more than one line the line break ’\n’ character can be inserted as shown below:

StateMachineFunctionPrefixCFile=#pragma vector=UART0TX_VECTOR\n__interrupt void

Prefixes for the header and the C file can be specified separately.

Using state machines with a real-time operating system

In this design each state machine usually runs in the context of an own task. The principle design is shown in the following figure.

Each task executes a state machine (often called active object) in an endless while loop. The tasks wait for new events to be processed from the state machine. In case no event is present the task is set in idle mode from the RTOS. In case one or more new events are available the RTOS wakes up the task. The used RTOS mechanism for event signaling can be different. But often a message queue is used. Events might be stored in the event queue from various sources. E.g. from within another task or from inside an interrupt service routine. This design can be realized with every real-time operating system. Only the event transport mechanisms might differ.

Benefits:

Efficient and well tested runtime environment provided from the real-time operating system
Prioritization of tasks, scheduling available
State machine processing times decoupled from each other.

Consequences:

Need of a real-time operating system (complexity, ram usage, cost …)

In the how-to section an example of this pattern is presented with FreeRTOS. The examples below shows code for the RTEMS and embOS.

Example code for RTEMS

// rtems specific task body
rtems_task oven_task(rtems_task_argument unused)
{
  OVEN_INSTANCEDATA_T inst = OVEN_INSTANCEDATA_INIT;
 
  for ( ; ; ) {
    // returns if one event was processed
    oven(&inst);
  }
}
 
 
// generated state machine code
extern rtems_id Queue_id;
uint8_t msg=NO_MSG;
size_t received;
rtems_status_code status;
 
void   oven(OVEN_INSTANCEDATA_T *instanceVar) {
 
  OVEN_EV_CONSUMED_FLAG_T evConsumed = 0U;
 
 
  /*execute entry code of default state once to init machine */
  if (instanceVar->superEntry == 1U) {
    ovenOff();
 
    instanceVar->superEntry = 0U;
  }
 
  /* action code */
  /* wait for message */
  status = rtems_message_queue_receive(
             Queue_id,
             (void *) &msg,
             &received,
             RTEMS_DEFAULT_OPTIONS,
             RTEMS_NO_TIMEOUT
           );
  if ( status != RTEMS_SUCCESSFUL )
    error_handler();
  }else{
    switch (instanceVar->stateVar) {
      // generated state handling code
     …
    }
  }
}

Example code for embOS RTOS from Segger.

// state machine instance
SM_INSTANCEDATA_T instanceVar = SM_INSTANCEDATA_INIT;
 
// Task and queue objects.
static OS_STACKPTR int Stack_TASK_1[128];   /* Task stacks */
static OS_TASK         TCB_TASK_1;         /* Task-control-blocks */
static OS_Q            MyQueue;
static char            MyQBuffer[100];
 
OS_TIMER MyTimer;
 
char txbuf[32] ;
 
// Routine called from the embOS RTOS to signal 
// a timeout. A timeout event is sent to the state
// machine. Multiple timer callback functions might be created if
// several timers are needed at the same time. Each one then fires an own
// event. E.g. ev50ms or ev100ms
static void MyTimerCallback(void) {
 
    uint8_t msg=evtTimeout;
 
    OS_Q_Put(&MyQueue, &msg, 1);
}
 
// Task blocked until a new event is present. The new event is 
// then sent to the state machine.
static void TaskRunningStateMachine(void) {
    char* pData;
 
    while (1) {
        // waiting for new event
        volatile int Len = OS_Q_GetPtr(&MyQueue, (void**)&pData);
        volatile char msg = *pData;
 
        sm(&instanceVar, (SM_EVENT_T)msg); // call generated state machine with event
 
        OS_Q_Purge(&MyQueue);
 
    }
}

Events versus Boolean Conditions

Sinelabore supports two basic modes of operation. Either the generated state machines react on events. Only if an event is present a transition is taken (e.g. evDoorClosed, evButtonPressed). Events are eventually send to the state machine using an event queue (see above). Alternatively transitions are triggered by boolean conditions. If a boolean condition is true a state change happens (e.g. DI0==true). The latter one is useful if binary signals should be processed like shown in these two designs (signal shaping function blocks)(PLCOpen function block). In this case the state machine runs without receiving a dedicated event. Based on the current state, conditions derived from boolean signals are used to trigger state transitions.