John LonerganI wrote up some docs on what I've been seeing as strange results for stray capacitance on the GPIO pins. See "Stray Capacitance" in the GitHub README for full details.
I can't understand how the signal takes so long to decay - am I wrong about this being just RC from the pcb trace & zif socket? The RC would be tiny but the decay takes 25 secs.
?????
Discussions
Become a Hackaday.io Member
Create an account to leave a comment. Already have an account? Log In.
One of the hits I got is a Cornell University course that says: "The input impedance, in either state, of CMOS gates is typically 10^12 Ω. The input capacitance is 5 pF."
Do those values give you numbers closer to what you observed?
Are you sure? yes | no
Hmm? ...Well if it was 10^12 ohm rather than 100mohm and I assume 20pf in the input plus the trace plus the zif then I think it comes to 20secs which is definitely in the right ballpark. That's really helpful Ken if this is right. Thanks i'm not bonkers after all.
Are you sure? yes | no