GPIO pin safety


5 posts
by jwhitehorn » Fri Jan 11, 2013 5:07 pm
I have a couple of question regarding safety with the GPIO pins.

Firstly,

Is it safe to open a GPIO pin for output, and set it to "1" when nothing is attached to the pin? I've been testing an app to detect pin value changing, and I've been just raising (via software) the pin high/low with nothing attached just to test my app. Just making sure it's safe.

Secondly,

When I have a circuit on my breadboard and I want to change it up, do most people do this while the Pi is running? Out of fear I've been shutting down my Pi before switching out my projects.

Thanks!
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by aTao » Fri Jan 11, 2013 5:19 pm
jwhitehorn wrote:I have a couple of question regarding safety with the GPIO pins.

Firstly,

Is it safe to open a GPIO pin for output, and set it to "1" when nothing is attached to the pin? I've been testing an app to detect pin value changing, and I've been just raising (via software) the pin high/low with nothing attached just to test my app. Just making sure it's safe.


Totally safe

Secondly,

When I have a circuit on my breadboard and I want to change it up, do most people do this while the Pi is running? Out of fear I've been shutting down my Pi before switching out my projects.

Thanks!


My choice would be disconnect or turn off for a major change, minor revisions may well be done live. Certainly testing is best done live. But consider "Oops I didnt mean to connect that there" with "Oops BANG"
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by jfornango » Sat Jan 12, 2013 7:16 pm
When in doubt, be paranoid.
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by Grumpy Mike » Sat Jan 12, 2013 11:07 pm
Yes connecting stuff to any electronics that is powered up is always risky. The slightest brush with a wire to the wrong place can result in disaster.
In order of badness you should not:-
1) connect / disconnect the ground on a powered up system.
2) connect / disconnect the power on a powered up system.
3) connect / disconnect the signals on a powered up system.

Feeding signals into a device that is unpowered is perhaps the worst thing you can do.
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by jwhitehorn » Sun Jan 13, 2013 1:21 am
Thank you all for the wonderful input.

I agree, playing it safe is good. I've been, and will continue to, power down the Pi when changing up my breadboard.
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