Hardware damage from executing tight polling loop over extended periods of time?

Question

I want my project to be standing by at the ready for months and years at a time, so I started writing my code to throttle back from polling at delayMicroseconds to just delay. Like, after 15 minutes with no user input, switch from 10 microsecond delay intervals to 10 millisecond (or even 10 second intervals). I wonder if spinning its wheels at warp speed for months on end will wear a path in the circuit pathways? This has got to be a stupid question (or at least make someone chuckle), but I'm really 50/50 at this point: worth the effort for the extra code or won't make a lick of difference? (I know there's my implementation and then there's the right one, but this is where I am right now. FYI, I went with 17 GPIO's in parallel to link my Pi to my teensyduino. add 17 optocouplers, hot glue, hinges, scavenged enclosures etc and this thing looks ridiculous. But I LOVE IT! (It's a mouse that I control over the web)

EDIT Although I didn't mention any concerns about using batteries, their mention didn't really detract from anything. Rather, I welcomed their inclusion because I realized that I had overlooked things more fundamental. I'm always telling others how important ventilation can be and the impact heat can have, but it went right by me this time!

I do value and appreciate the feedback I have gotten. I don't think I will be writing any code to vary polling speed after timing out. But I would still like if someone wanted to directly answer the specific concern I had when posting this question: "At certain times, my program waits for a GPIO pin to change states. I am using the polling method to determine the status of the pin, and I am using this bit of code to do so:

do
{

} while (digitalRead(pin#) == 0); //wait for pin to go high

So, my question is, "Does it make any difference at all, in terms of wear & tear or stress placed on the CPU, how many loops I choose to make in one second? I'm considering something in the range 0.1Hz -> 100kHz Assuming that I keep heat under control and other vital parameters within their nominal operating levels, is it true that the frequency I choose won't make a bit of difference, one way or another?"

Thanks in advance for any interest given to this question.

Answer 1

There's nothing to save except battery charge (if your system even uses a battery). It will take just as much energy to delay() as it would to keep polling. The only way to save energy is to put the processor to sleep instead of delaying. And polling will be so brief that you might as well keep the sleep time short, too.

You probably don't need 10 uSec poll intervals; I should think your mouse would be plenty responsive with 1 mSec intervals. If polling takes, say, 100 uSec (and that's a total guess) and you sleep the processor for the other 900 uSec, you'll cut the energy use by 90%. If you don't need to save energy, it won't matter whether, or how long, you delay.

Update:

"Does it make any difference at all, in terms of wear & tear or stress placed on the CPU, how many loops I choose to make in one second? I'm considering something in the range 0.1Hz -> 100kHz Assuming that I keep heat under control and other vital parameters within their nominal operating levels, is it true that the frequency I choose won't make a bit of difference, one way or another?"

Yes, it is true. Your CPU can run full speed continuously, safely. It won't overheat from continuous running. Only if some part of your project is trying to draw too much current through the CPU; then that will cause heating, but the CPU polling a bunch of inputs is well within its specs.

Answer 2

For many applications within the realm of Arduino software & hardware development, the only practical concern is to limit the need to write to non-volatile types of memory. Non-volatile types of memory, such as that which stores the Arduino program, do have a finite number of write cycles. However, it is in the 10s (perhaps 100s) of thousands of writes. So is not a concern to most developers.

Running code, however, does put a load on the processor's power source. First we need to understand that a switch in a modern processor require only a minuscule amount of current if left alone. But if asked to change from a 0 to a 1 or 1 to 0, the current spikes. In processors pushed to their limits with 100s of thousands of switches, this extra current turns into heat which must be mitigated less damage is done.

Fortunately, most processors used in Arduinos are not pushed to their limits. So this is rarely a concern. To be clear, the processor chip used on most Arduinos will mostly likely not need a heat sink or fan.

However, even for an Arduino not pushed to its limits, this extra power demand is devastating to the long term life of portable battery operated devices. Programming an Arduino to extend battery life is by no means a trivial task. And certain processors (Arduinos can be made with many different processors) are orders of magnitude better at this then others. But, since most Arduino applications are powered from mains, this too is of little concern.