Some basic questions about real-time strategies and synchronization

lost underflow

Prodigy 50 points

Other Parts Discussed in Thread: SYSBIOS

DM814x / CCS5 / SYSBIOS

I have two functions that I need to implement.

One is image processing running at 60Hz, triggered off a GPIO pin (lower priority.)

The other is filter updates running at a higher frequency triggered periodically internally (higher priority).

My strategy was going to be a HWI for the GPIO and a TIMER for the filter update.

I don't want to stay too long in the HWI or TIMER so, I am going to create two tasks, using appropriate priorities.

I am unsure whether the task should have the functionality within a loop and pend on semaphores, which the HWI/TIMER will issue, OR

Have the functionality not within a loop and have the HWI/TIMER kick off the tasks again and again.

I am obviously confused, and any help will be appreciated.

Thanks.

over 13 years ago

0 ScottG over 13 years ago

TI__Mastermind 26780 points

Lost,

You should take the first approach, with the Task functions as loops, blocking on Semaphores while waiting to be triggered again.

Doing this will allow the tasks to cycle between the READY, RUNNING and BLOCKED states.

If your task function were to just exit when done with one pass of processing they would end up in the TERMINATED state, and wouldn’t run again. Section 3.5.2 of Bios_User_Guide.pdf has a good picture to show this behavior…

If you haven’t seen it, there is SYS/BIOS wiki page (http://processors.wiki.ti.com/index.php/Category:SYSBIOS) with some online training that may be of help: http://processors.wiki.ti.com/index.php/SYS/BIOS_Online_Training

Scott

0 lost underflow over 13 years ago in reply to ScottG

Prodigy 50 points

Perfect.

Thanks.

Processors

Processors forum

Some basic questions about real-time strategies and synchronization