Electronics > Beginners
Strange behaviors with microcontroller digital inputs
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tyguy2:

--- Quote from: Kasper on September 23, 2019, 07:55:23 pm ---My guess is something happens after a while that causes your MCU to start rebooting constantly and the pin states change during the reboot.  Displaying a count through serial monitor will tell you if it has rebooted or not. Note that your counter variable will eventually overflow, possibly making it look like a reboot but if it only happens at a power of 2 then that should be obvious it was just an overflow.

--- End quote ---

My code currently has variables that exist only in RAM, and I'm guessing constant resets would wipe those from memory and reset them to their initial values, but I'm observing nothing like that.


--- Quote from: mikerj on September 23, 2019, 07:58:37 pm ---The schematic shows a direct connection between the micro's GPIO pin and the output of the LDO, with no series resistors.  If the voltage on the micro pin is 1.23v but the voltage at the LDO is 3.3, then there must be a bad connection between them.

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If that were true, then we wouldn't see the same effect on the reed switch. Additionally, as I said in the previous post, I'm getting 3.3v AC RMS on the inputs, which means something is definitely wrong with the micro, not the voltages going into the micro.
mikerj:

--- Quote from: tyguy2 on September 23, 2019, 11:38:44 pm ---
--- Quote from: mikerj on September 23, 2019, 07:58:37 pm ---The schematic shows a direct connection between the micro's GPIO pin and the output of the LDO, with no series resistors.  If the voltage on the micro pin is 1.23v but the voltage at the LDO is 3.3, then there must be a bad connection between them.

--- End quote ---


If that were true, then we wouldn't see the same effect on the reed switch. Additionally, as I said in the previous post, I'm getting 3.3v AC RMS on the inputs, which means something is definitely wrong with the micro, not the voltages going into the micro.

--- End quote ---


Sorry, I must be missing something here.  Just to confirm, you are measuring 3.3v AC RMS on the micro GPIO pins, including the one directly connected to the output of an LDO where you are getting 3.3v DC?  Are you using the same ground reference when measuring the micro GPIO pins and the LDO output?
Nominal Animal:
I'd wager a beer that the problem is that internal pull-ups or pull-downs are enabled for those pins, and the resistors resistance is smaller than intended.
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