Comments for uC Hobby

Comment on Resource Links by admin

admin — Tue, 24 Jan 2012 09:58:33 +0000

@ElectroNick, your site is awesome, of course you can plug your blog. I will add your link to the list. I hope you will do the same on your end.

Comment on Resource Links by ElectroNick

ElectroNick — Mon, 23 Jan 2012 16:21:14 +0000

Can I shamelessly plug my own blog for this great list?

http://elabz.com/ has mostly laser, CNC and mechatronics (robots, motor control) related projects and resources.

Thanks!

Comment on Replacing delay() in Arduino Sketches – IsTime() to the rescue! by EmbeddingSome

EmbeddingSome — Mon, 23 Jan 2012 16:12:36 +0000

Despite the special handling needed for time-sensitive applications (and that would probably only affect clocks and long-time data loggers) , the IsTime() idea is very useful for anything from button debounce to PWM motor control, POV displays and much more. I always re-write the part of the code that contains delay() if I’m using someone else’s code and never use delay() myself – it never actually made any sense to me to make the uC literally stop for any period of time – there’s always a useful task that can be completed during that time.

Comment on Replacing delay() in Arduino Sketches – IsTime() to the rescue! by Axel Werner

Axel Werner — Sun, 22 Jan 2012 21:12:16 +0000

the idea is good. but as far i understand it it will not save me much code or headache if i use it instead of doing it manualy setting up two variables for “lastTime” and “interval” and then do a if(millis()-lastTime>interval) { lastTime=millis(); do more stuff here;}

Comment on Replacing delay() in Arduino Sketches – IsTime() to the rescue! by admin

admin — Sun, 22 Jan 2012 05:25:07 +0000

@ah I see your point now. Thank you! I just did not think about how the roll over would happen with the math. I actually did a test to prove it to myself.

Comment on Replacing delay() in Arduino Sketches – IsTime() to the rescue! by ah

ah — Sun, 22 Jan 2012 01:48:33 +0000

Well even after 50 days it’s not a problem.

Let’s say that you program is running for 4294967286 ms (which is 10 ms before overflow). And now you will call IsTime function next after 20ms. So the millis function return 10. Without any consideration of overflow you calculate this:

10 – 4294967286

And because the overflow (wrap around) nature of unsigned long the result is 20. It’s same result as if you calculate your formula for “overflow correction”:

(MAX – 4294967286) + 10

Actually result is 19 because you don’t consider the fact that actually overflow from MAX to 0 takes 1ms but it’s just a detail.

My point is if you skip the Rollover detection the behavior of IsTime function will be exactly the same.

PS: The code https://gist.github.com/1654676 is not in C# it’s C. Git just put the “#” character as a link after “C” – a bit unfortunate

Comment on Replacing delay() in Arduino Sketches – IsTime() to the rescue! by Michael

Michael — Sun, 22 Jan 2012 01:27:36 +0000

Nice idea! I do something cruder for timing the main loop events in my AVC robot Data Bus. I may use this instead. Thanks!

Comment on Replacing delay() in Arduino Sketches – IsTime() to the rescue! by admin

admin — Sun, 22 Jan 2012 00:32:39 +0000

@ah… Thanks I added those links to the article. I do feel that the overflow handling is necessary. It will occur in about 50 days. If you have a project that runs for months the overflow could cause issues. Its not hard to fix. The only requirement now is that you call the IsTime function once every 50 days and the overflow will not be an issue. Yes its a very unlikely thing, but again, easy to fix.

Its a surprise that the C# solution was named IsTime() as well. I’ve been using this trick for about 15 years. Its a simple way to get multi-tasking type performance.

Comment on Replacing delay() in Arduino Sketches – IsTime() to the rescue! by ah

ah — Sun, 22 Jan 2012 00:19:51 +0000

Nice article. It si similar approach as in http://www.arduino.cc/en/Tutorial/BlinkWithoutDelay

And by the way. Because you are using unsigned long the overflow handling is unnecessary. The IsTime function can look like https://gist.github.com/1654676 with same functionality.

Comment on Site Update – Things are Changing by foz

foz — Sat, 07 Jan 2012 03:55:31 +0000

glad you’re back, looking forward to new posts