Hello guys I am currently working on a project. and I would like to turn on a GPIO pin when my LED on the circuit below turns on. I'm lost to where I should tie my input GPIO pin. please help. Thanks!
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How to use a NPN transistor to "turn on" a Rpi GPIO pin?
Answer
Ah, you cannot "turn on" a Rpi GPIO pin. She won't listen to you, but you can ask her to behave as input or output! :)
In geek English:
A Rpi GPIO pin can be in "input mode" or "output mode".
An "input" pin can input/read a signal which can be High or Low.
An "output" pin can output/switch a LED, eg, High to switch on, Low to switch off, (or vice versa, depending on circuit).
I have drawn a circuit showing how to convert a loud (5V) signal to a soft (3V3) signal. The fair lady prefers a soft voice - loud voice can kill her! :)
/ to continue, ...
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