Timer Based Rate Group Drivers

[LeStarch]

The standard implementation of a timer-driver rate group driver is the following pseudo-code:

while (true) {
    // Runs withing timer component
    block_until_timer_tick();
    this->Cycle_out(0);  // Start rate groups
}

The execution context of this is within the main thread.

The inner two lines must be within a timer component. The question is should the while (true) be within the component or placed in the main function?

If placed within the component, then the component owns the main program loop. Users cannot adjust what is done. However, it does mean the implementation of loop-until-stop can be hidden in the component.

If placed within the main loop, users can "add" steps to the main loop, but are required to handle the stop functionality for system shutdown.

[LeStarch]

fprime-zephyr and fprime-baremetal both implemented this as a while-loop-in-main-function. This was because often deeply embedded systems often need to poll other things as part of the main loop.

Linux and VxWorks implemented this as while-loop-in-component to simplify the main function.