Do GPIO output pins bounce?

[lrhorer]

Does anyone know if setting or re-setting a GPIO output pin to its current status will cause the pin to bounce? IOW, if the pin is set high, and one issues a command in Python to set the pin high, does it momentarily drop low, or vice-versa?

[PeterO]

You are asking about "glitches" rather than "bounces". Bounces are normally taken as being multiple transitions on a state change.

To answer your question , GPIO outputs are glitch free.

PeterO

[HermannSW]

To answer your question , GPIO outputs are glitch free.

That is good to hear!

I do control 38V/1.5A led drivers powering a 5000lm led via two 24V IRF520 mosfets in series. GPIO13 is connected to SIG pin of both IRF520 modules. When Pi GPIO13 goes from high to low I would expect this:

Code: Select all

‾‾‾‾‾‾‾‾|_______

What my 100MSps logic analyzer sometimesshows is this

Code: Select all

‾‾‾‾‾‾‾‾|_|‾|______

or even this

Code: Select all

‾‾‾‾‾‾‾‾|_|‾|_|‾|______

with width of the short pulses being 10ns.
So is this a problem of having reached maximal resolution of the logic analyzer, or is this real?

[even if it is real, that is no problem for my application, but I want to know]

[FTrevorGowen]

...
I do control 38V/1.5A led drivers powering a 5000lm led via two 24V IRF520 mosfets in series. GPIO13 is connected to SIG pin of both IRF520 modules. When Pi GPIO13 goes from high to low I would expect this:

Code: Select all

‾‾‾‾‾‾‾‾|_______

What my 100MSps logic analyzer sometimesshows is this

Code: Select all

‾‾‾‾‾‾‾‾|_|‾|______

or even this

Code: Select all

‾‾‾‾‾‾‾‾|_|‾|_|‾|______

with width of the short pulses being 10ns.
So is this a problem of having reached maximal resolution of the logic analyzer, or is this real?

[even if it is real, that is no problem for my application, but I want to know]

Historically I've always used oscilloscopes (never had a "logic analyser" and no longer have access to a 'scope) but maybe what the analyzer is showing is its "interpretation" of "ringing" caused by probe/cable mis-match?
Trev.