Real-Time Workshop User's Guide

Main Program

Overview of Operation

The following pseudocode shows the execution of a Real-Time Workshop Embedded Coder main program.

main()
{
  Initialization (including installation of rt_OneStep as an 
    interrupt service routine for a real-time clock).
  Initialize and start timer hardware
  Enable interupts
  While(not Error) and (time < final time)
    Background task.
  EndWhile
  Disable interrupts (Disable rt_OneStep from executing.)
  Complete any background tasks.
  Shutdown
}

The pseudocode is a design for a harness program to drive your model. The ert_main.c program, as shipped, only partially implements this design. You must modify it according to your specifications.

Guidelines for Modifying the Main Program

This section describes the minimal modifications you should make in your production version of ert_main.c to implement your harness program.

• After calling model_initialize:
• Initialize target-specific data structures and hardware such as ADCs or DACs.
• Install rt_OneStep as a timer ISR.
• Initialize timer hardware.
• Enable timer interrupts and start the timer.

Note    The real-time object is not in a valid state until model_initialize has been called. Servicing of timer interrupts should not begin until model_initialize has been called.

• Replace the rt_OneStep call in the main loop with a background task call or null statement.
• On termination of main loop (if applicable):
• Disable timer interrupts.
• Perform target-specific cleanup such as zeroing DACs.
• Detect and handle errors. Note that even if your program is designed to run indefinitely, you may need to handle severe error conditions such as timer interrupt overruns.

You can use the macros ssGetErrorStatus, ssSetErrorStatus, and ssSetStopRequested to detect and signal errors, or to stop execution. These macros are documented in the Writing S-Functions manual.

Overview

rt_OneStep