Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: Resilient on February 14, 2009, 08:28:01 PM

Title: How not to kill my Axon
Post by: Resilient on February 14, 2009, 08:28:01 PM

So I am just getting started in robotics and am making my first project with the Axon.

I want to make sure I don't fry anything though.  What are things I want to avoid?

For example, the FAQ says the following:

Quote

If for example you accidentally plug in ground to an output pin while the pin is set to high, the pin will most likely fry.

I am not entirely sure what an output pin is in this case.  Does it mean the signal pin for one of the servo ports?

And what about the sensors?  If I accidentally short the ground and +5v on the sensor pins can that kill something?

Sorry for being such a noob.  I know more about the programming side of things than the electrical side of things.

Title: Re: How not to kill my Axon
Post by: Razor Concepts on February 14, 2009, 09:19:28 PM

Quote from: Resilient on February 14, 2009, 08:28:01 PM

I am not entirely sure what an output pin is in this case.  Does it mean the signal pin for one of the servo ports?

Yes

Quote from: Resilient on February 14, 2009, 08:28:01 PM

And what about the sensors?  If I accidentally short the ground and +5v on the sensor pins can that kill something?

If it's only for a a short amount of time(like a second or so), everything should be fine.

Before you power up, double check any new connections to ensure that they're plugged in correctly. Also Admin noticed that the voltage regulator works well in protecting the axon, he plugged in his batteries the wrong way (basically fatal to unprotected microcontrollers), but the Axon survived after 10 seconds.

Title: Re: How not to kill my Axon
Post by: Resilient on February 14, 2009, 11:06:01 PM

And what about the signal pins, how much current can they take?

It seems like in this example of a photoresistor (http://www.societyofrobots.com/schematics_photoresistor.shtml) it would be a problem if the photoresistor was exposed to very bright light and its resistance went way down then you could get a lot of current through the signal pin?

Title: Re: How not to kill my Axon
Post by: Razor Concepts on February 14, 2009, 11:31:36 PM

Nope, don't worry about that, because the photoresistor will never have a resistance low enough to allow that much current in.

Title: Re: How not to kill my Axon
Post by: Soeren on February 14, 2009, 11:42:56 PM

Hi,

To simplify...
If an I/O pin is set as an output, you should never short it to Vss (ground/0V) or Vdd (the positive voltage), or anything else for that matter, since the controller powers the pin. However, if the output is low (0V), shorting it to ground will do no harm, as there is no potential difference, same goes for a high output shorted to Vdd.

An I/O pin set as an input pin, on the other hand, can be shorted to any voltage potential between Vss and Vdd, for as long as you like, since it is an input and supposed to get... Well, an input. (It has nothing to do with potential dividers).

Title: Re: How not to kill my Axon
Post by: Resilient on February 15, 2009, 12:31:26 AM

Thanks for the help!

That pretty much answers my questions for now.  :)

Title: Re: How not to kill my Axon
Post by: Admin on February 19, 2009, 07:15:55 AM

Hmmm just noticed you posted this in two places . . . see my reply on the other forum . . .
http://forums.trossenrobotics.com/showthread.php?t=2928