MEROS++

Minimal Embedded Real-time OS written in C++

Features

• C++ interface
• Static memory allocation: Stack area of each task is statically allocated
• Easy to port: Few knowledge of Assembly language required

Requirements

• Compiler: arm-none-eabi-gcc, arm-none-eabi-g++ 4.9.3

How to port MEROS++ into your project

1. Modify 4 functions in merospp_port.hpp

   • disable_interrupt()
   • enable_interrupt()
   • store_stack_pointer()
   • restore_stack_pointer()

   Default functions are for STM32 Cortex M4.

2. Include merospp.hpp, then instantiate Tasks and the Scheduler

   #include "merospp.hpp"
   
   // You can derive Task class like:
   class TaskDerived : public merospp::Task
   {
       public:
       TaskDerived( const uint32_t priority, const uint32_t period, void (*callback)(void) )
       : merospp::Task( priority, period, callback )
       {
   
       }
   };
   
   void callback1()
   {
       // do something
       // DO NOT PUT INFINITE LOOP inside
   }
   void callback2()
   {
       // do something
       // DO NOT PUT INFINITE LOOP inside
   }
   
   merospp::Task t1(5, 500, callback1);  // callback1 is called every 500ms
   TaskDerived t2(4, 1000, callback2);  // callback2 is called every 1000ms
   
   // Get the instance of Scheduler
   // Stack size: 64 words for t1, 128 words for t2
   auto& scheduler = merospp::Scheduler< 64, 128 >::get_instance( t1, t2 );

3. Place schedule() inside an interrupt handler that is called periodically

   void timer_callback()  // "HAL_TIM_PeriodElapsedCallback" for STM32
   {
       scheduler.schedule();
   }

4. Place run() inside main()

   int main()
   {
       /* Peripheral setup start */
       
       /* Peripheral setup end */
       
       scheduler.run();
       return 0;
   }

5. Build your project

   Please refer to CMakeLists_sample.txt for recommended compile options.

Acknowledgements

• CMake example project for STM32 and CubeMX