Any capacitor added to remove stray pickup should be in parallel withthe switch contacts.
Note: GPIO 3 (and also GPIO 2, pin 3) already has an external 1k8 pull-up, so the internal 50k pull-down won't make much difference.
So when the system is halted (after the sudo shutdown OS command is issued), does the system wait for GPIO3 to go low to boot back up? Would a really quick pulse to ground cause it to boot, or is it still sampling at 250MHz while halted?Burngate wrote: ↑Sun Jan 13, 2019 10:47 amNote: GPIO 3 (and also GPIO 2, pin 3) already has an external 1k8 pull-up, so the internal 50k pull-down won't make much difference.
I do have a metal case. So there's no other choice but to have a non-conductive case? Should I insulate the RPi from the case?wh7qq wrote: ↑Sat Jan 12, 2019 7:41 pmIt is possible to generate some extreme voltages when walking across carpeting, especially synthetics, with leather soled shoes. Steve Wozniak of Apple Computer fame has a nice video on the subject and you can probably find it on line somewhere (try https://www.youtube.com/watch?v=hLOQ7zOWGAA). The RPi is pretty robust but the kinds of voltages you can generate, especially in a cold, dry climate, can potentially damage most electronic devices. Check out the video if you can...worth watching.
That said, if the case and switch are non-conductive, an external pull-down on the GPIO pins might help...say 4.7k or 10k. If the case is metal and shares ground with the RPi, all bets are off.
Don't I need a series resistor with it for an RC time constant? I don't want to damage anything by having only a cap.
On the schematic PDF it's labelled R23
Ohmeter reads infinity RPi gnd to case, with and without cables from switch connected. Any point on case to any point on case is infinity as well. If I probe across the pushbutton terminals, it's infinity disconnected and 60 x 200k = 12MOhm connected.Idahowalker wrote: ↑Tue Jan 15, 2019 2:14 amGot an Ohm meter? If so what is the resistance reading between the case and the RPi common, GND?
Ohm with and without cables connected. Connect one cable at a time and ohm. If you get less then Infinity that's a problem. When you take the Ohm measurements do not touch the case or the ohm meter leads with your hand or other body part. Ohm one part of the case to the other, infinity?
Take the unit apart, clean out the dust, even the tiny bits of dust.
Other steps, wrap the case in foil, poke holes in the foil for air flow, and hook a ground to the foil. Ground being the 3rd wire from the power plug. The GPIO pin labeled ground is not really ground, more it is a circuit common.
Get a humidifer and run it.
Also, try not to zap the RPi anymore then needed. With common room conditions you can generate 5,000 volts per inch of spark, basically, Those tiny junctions inside those chips cannot take much of such treatment.