DIGITAL GPIO start-up glitch

Hardware
21

Hi,

The glitch also happens when the spark awakes from deep sleep. If you use sensors with negativ trigger logic like DHTxx you should change to analog pins (which a have to test now)

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22

Related but separate - pins D0-D2 on my Core sink current for about 7-8 seconds during program flashing (I just have LEDs fed from 3.3V through resistors to those pins). Is that normal? Is there a way to prevent that?

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23

Hi @SaratogaDude,

Thatā€™s a really interesting question. Iā€™ll ping @satishgn / @mohit about that one in case they have a chance to chime in. Iā€™m guessing it has to do with time spent in the bootloader in JTAG mode or something similar.

Thanks,
David

24

@Dave, @satishgn, @mohit, has anything been resolved/documented regarding the GPIO glitching on reset?

25

Heya @peekay123,

I know thereā€™s been a ton of activity in firmware land, but I donā€™t know about this issue specifically, hopefully those guys can chime in. :slight_smile:

Thanks,
David

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26

In order to pull some threads about this issue together, I created a new topic in the troubleshooting section

Even in this old thread, since the issue is still a sore point in my - and other peopleā€™s - eyes

27

I solved this very simply by using the fast io functions to set the desired initial value before configuring as an output and thus driving the output line.

   pinSetFast(pin); // initialize to HIGH
   pinSetMode(pin, OUTPUT);  // enable output

or

   pinResetFast(pin); // initialize to LOW
   pinSetMode(pin, OUTPUT);  // enable output

In reality, the library should have a setPinMode that takes a third argument which is the initial value. In my case I have some outputs that are active low and some that are active hi so I wrote a generic wrapper so I can change an output from active high to active low later and not worry about spreading HIGH and LOW around my code:

See my post here for details,

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28

As said there, that's not addressing the original problem.

And in order pull the discussion about this together into one thread I had opened the other thread.
So I'll now close this one to keep people from double posting.

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