Hi guys,
Today I did something wrong on my breadboard and while measuring my pwm pin output current that is controlling one tip122 transistor I saw 80 ma current from my pin.
How is that possible?
It has been working 5-10 minutes this way before I noticed the problem.
How. Is that possible and why my arduino pins are still working?
Is it possible that the pins are working but something else is damaged?
Thanks 
It's possible.
It's possible that you were just lucky.
It's possible that a failure will occur in the future.
controlling one tip122 transistor I saw 80 ma current from my pin.
It's also possible that you weren't using a current-limiting resistor.
Rob
Graynomad:
controlling one tip122 transistor I saw 80 ma current from my pin.
It's also possible that you weren't using a current-limiting resistor.
Rob
I was, but another wire was shorting so the current was flowing throught the short wire instead of the resistor.
I was sure that I was damaged my board but its still working
Yikes, (sh)it happens.
Rob
tonko_lonko:
Hi guys,
Today I did something wrong on my breadboard and while measuring my pwm pin output current that is controlling one tip122 transistor I saw 80 ma current from my pin.
How is that possible?
Easily!
40mA is the rated maximum for a pin, it's what the manufacturer guarantees. Sure it'll do more, it might even survive ... but it invalidates your warranty.
I measured 250mA pulse output from a pin when doing some tests with LEDs so the arduino is capable of this. No doubt you have done damage to the output pin, it might fail some time in the future.
There is a region between normal operation and instant frying where damage is done but short of un encapsulating the chip and looking at it with a scanning electron microscope you won't know how much damage.
How. Is that possible
Yes, and even at higher current levels.
and why my arduino pins are still working?
Those things are quite hardy.
dhenry:
How. Is that possible
Yes, and even at higher current levels.
and why my arduino pins are still working?
Those things are quite hardy.
Ill tell you what dear henry, wait until every one has answered and then repeat some obvious information that has been mentioned before.
Oh that is what you normally do isn't it, I forgot.