Page 1 of 1

GPIO input voltage levels??

Posted: Sun Sep 08, 2013 10:51 am
by redhawk
As I understand the GPIO requires an input voltage to be either 0v or 3.3v for bit 0 and bit 1 and I'm also guessing this is controlled by a schmitt trigger prevent logic state bouncing.

Does anyone know what the exact voltage ranges for bit 0 and bit 1 are i.e. 0 - 1v, 3 - 3.3v etc, is this the same for every Pi or can the thresholds fluctuate due to temperature??

Richard S.

Re: GPIO input voltage levels??

Posted: Sun Sep 08, 2013 11:15 am
by AndrewS

Re: GPIO input voltage levels??

Posted: Sun Sep 08, 2013 11:47 am
by redhawk
Thanks for the tip the information has certainly proved interesting.
According to the docs the maximum low level voltage is 0.8v and minimum high level voltage is 1.3v (which is surprisingly quite low from 3.3v).

Does that mean I could use the voltage drop of red LED (approximately 2.0v) with load resistors at the source and input pin to provide GPIO input detection and protection??

Richard S.

Re: GPIO input voltage levels??

Posted: Sun Sep 08, 2013 11:54 am
by AndrewS
I'm afraid that's a bit beyond my knowledge! :(
You might find the "Buffered I/O, LEDs, and pushbuttons" section in the Gertboard manual interesting?