norex
Posts: 7
Joined: Wed Jan 09, 2013 12:50 pm

Are my GPIOs fried?! HELP!

Mon Jan 14, 2013 7:35 pm

Here is the short (... no pun intended) and skinny.
Bought a pi cobbler, soldered it up (totally did a bad job but I kind of fixed it, removing any solder bridges). After purchasing some jumper wires , I grabbed a small led out of a set of Christmas tree lights to see if I could use it on my breakout board. Not knowing anything (using my 3rd grade knowledge of power) I decided to wire one end to the Pi's 3v3 and the other to a ground. It lit up, so I thought nothing of it and decided to move on and get the thing blinking. I set my Pi up to use wiringPi's gpio command. I then wired one end of the led to gpio #17 and the other to ground (keep in mind I didn't use any resisters) and used the commands...
CODE: SELECT ALL
gpio mode 0 set
gpio write 0 1

in order to set gpio 17 high. Nothing not even a blink, in fact when ran "gpio read 0" I could see that the pin was still set to low. Upon further investigation I discovered that I can set any gpio that had nothing plugged in high, but the second I connect my led to that gpio it switches back to low. Has anyone seen anything like this? Am I missing something? Sound like a fried gpio? Someone please HELP!!

Full Disclaimer: I have tried multiple methods of toggling gpio pins... wiringPi//python//bash//webiopi

-rst-
Posts: 1316
Joined: Thu Nov 01, 2012 12:12 pm
Location: Dublin, Ireland

Re: Are my GPIOs fried?! HELP!

Tue Jan 15, 2013 2:13 pm

Maybe I don't quite get your explanation... The led only lets current in one direction, so if it is installed 'for output', the same pin can never be read as input :roll:

Obviously it is a good practice to always use a resistor. Generally you would most likely fry the led first though...
http://raspberrycompote.blogspot.com/ - Low-level graphics and 'Coding Gold Dust'

pjc123
Posts: 911
Joined: Thu Mar 29, 2012 3:37 pm

Re: Are my GPIOs fried?! HELP!

Tue Jan 15, 2013 2:45 pm

-rst- wrote:Maybe I don't quite get your explanation... The led only lets current in one direction, so if it is installed 'for output', the same pin can never be read as input :roll:

Obviously it is a good practice to always use a resistor. Generally you would most likely fry the led first though...
I was going to reply with the same response earlier today until I realized it was an inconsiderate poster that posted the same exact question in two different threads on the exact same day (within a couple of hours of each other no less) and it has since been solved in that other thread.....i.e. therefore wasting our time.
My Raspberry Pi Project Page:
http://www.flaminghellmet.com/launch/

User avatar
Burngate
Posts: 4971
Joined: Thu Sep 29, 2011 4:34 pm
Location: Berkshire UK
Contact: Website

Re: Are my GPIOs fried?! HELP!

Tue Jan 15, 2013 4:49 pm

pjc123 wrote:... it was an inconsiderate poster that posted the same exact question in two different threads ...
More likely a first-time poster who hadn't realized it takes time for his post to be modded ...

-rst-
Posts: 1316
Joined: Thu Nov 01, 2012 12:12 pm
Location: Dublin, Ireland

Re: Are my GPIOs fried?! HELP!

Tue Jan 15, 2013 5:31 pm

Ah, well...
http://raspberrycompote.blogspot.com/ - Low-level graphics and 'Coding Gold Dust'

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