Quote:
Originally Posted by Chris_Elston
You may have an excellent point there, except the watch dog errors have always been there. In the case where 100% CPU is seen, the watch dog error fill the driver station diagnostic window. If in the past, without the CPU chart, we would have seen the same watch dog errors fill the screen I assume due to high CPU usage, even though we could not see the CPU usage in year previous.
My logic is, if we did not see any watch dog errors in 2009, 2010, and 2011, then I assume maybe we did not have a MAX'ed out CPU Usage. This year, we see the CPU usage hit 100%, then we see the watch dog errors fill the screen, and teleop disables, and the robot shudders to a stop when we have too much loaded in the CRIO.
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The CPU just barely hitting 100% will not cause watchdog/motor safety errors on its own. Consider a simplified example where you run a single loop every 20 ms. If the loop takes 10 ms to run it will take 50% of the CPU. If it takes 20ms, it will use 100% of the CPU. The default value for a motor safety is 100ms, so it won't be until your loop takes more then 100ms that you will see a motor safety problem. I believe the system watchdog is even longer then that.
It gets a lot more complicated when you have multiple loops involved like the framework code. However, even this year, we've definitely had the CPU at 100% without watchdog/motor safety errors.