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Am I burning out my gpio pins?

gpio nano

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#1 occamsquattro



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Posted 15 January 2016 - 01:29 AM

I am a first-timer, learning how to work gpio outputs.


I'm attempting to run a 12v LED using a solid state relay (VO14642AT, datasheet here: http://www.vishay.co...46/vo14642a.pdf. I had gpio8 (J8-1 in this diagram: http://learn.linkspr...ader-Model.jpg) connected to anode through a 1kOhm resistor (981Ohm measured) and a 1n4001 diode (for good measure), and GND (J8-7) connected to cathode.


This was working for a while, but gpio8 seems to have just stopped working. Measuring voltage, it seems to just float between 1 and 150mV, no matter what I set in software (I'm just using command line to write a 0 or 1 to /sys/devices/virtual/misc/pin/gpio8).


So I assumed I shorted it while being careless. I moved on to using gpio9, and was again getting good results for a while. But now gpio9 is misbehaving as well. But rather than floating, I read about 0.29mV on low, and 0.735mV on high.


Help! At this point I'm afraid to try anything else!

#2 youkee


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Posted 16 January 2016 - 08:43 AM

max out current of gpio on pcDuino3 is only 4mA, and the high leve is 3.3V. I think pcDuino8 Uno has same limitation.


I am not sure the Voltage and current of GPIO pins on pcDuino8 Unu is compatible with your driver circuit. 


In my opinion,  first you can try to control it with Arduino Uno, to make sure your driver circuit is work properly.

#3 occamsquattro



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Posted 16 January 2016 - 04:30 PM

Thanks for replying!


Maybe my math is wrong?? I calculate the current from gpio to the transistor at 3.3mA: 3.3V / 981Ohm = 0.00336


So I thought I was within spec? I am also adding resistance through the diode, but I'm not sure how to calculate how much resistance it's making.

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