Easy Led Visual Test For Digital Ports Tutorial J Starnes


I'm considering making a whole board that plugs into the ezb and can test them all at once. Thanks guys for the compliments. I try to do things that are simple enough to repeat with a few pictures. Winky


I made at work a pcb testers that checks all outputs on a board after it get stuffed
called "pins of nails tester",but for EZB would be to hard and some testers i added vacuum.

BUT how i check mine very easy is using a breadboard, a meter and a few leds ,its simple easy and fast


I see you didnt use a resistor to limit the current,what will happen it may burn out the outputs.

ON 5 volts you need 470 ohm to 510 ohms,some do use 330 ohms but not really good led gets very bright and not needed ,its only to test the output.

not light up the whole house .LOL


Why would anyone need a resistor? Just to bring 5v down to 3 volt?


thats not the problem resistor is not for voltage its for current,simple ohms LAW
even at 3 volts you run the circuit at you still need a resistor to LIMIT the current


Ohms law.. OK I'm not going there. It works for me and they draw under 25ma max for ezb digital port.


Hey Doug , I would love to have a room a that would be awesome! Of course I would EZ robotify it Winky. I'll message ya tommorow its time for bed here.


If it works for great.but still its not the correct way to do it,look at the circuits on the internet is shows to use a resistor,second leds mostly made for 10 ma and you arer driving at 25 ma more then twice the current so its bad for for the led too.

this is what dougpope ask too
Your LED-Jumpers idea is GREAT ! What limits the LED Current to 5 or 10 Milliamps ?


Ohms law indicates - Amps is limited by the resistance of the circuit at a given voltage. For current to increase so would voltage input and its works in reverse as well. Lower the voltage input and current will lower as the resistance of the circuit remains the same. There's no reason for a resistor in this device.... In this case a led does not draw more than the current rating of ezb digital outputs. Lets not make a simple and easy to use tutorial get complicated for no good reason for a new user that does not understand ohms law and its uses. Winky okie dokie


ok,just trying to help you from a burned led, when driving a led at more then the correct current it will burn out
I only bought it up because of dougpope comment and his is right about it too. Smile