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by hawaiiankong
Mon Nov 11, 2019 4:11 pm
Forum: Troubleshooting
Topic: All GPIO's dead but RPi 3B+ still works as normal - Follow-up
Replies: 10
Views: 492

Re: All GPIO's dead but RPi 3B+ still works as normal - Follow-up

No comprehensive electrical specification for the Pi SoC is publicly available but I am surprised a 30mV offset would cause problems for a Pi. I wouldn't have expected sinking -30mV on one pin to take out the entire GPIO port. A single pin failure, as you have now experienced, could lead to a casca...
by hawaiiankong
Sat Nov 09, 2019 2:34 pm
Forum: Troubleshooting
Topic: All GPIO's dead but RPi 3B+ still works as normal - Follow-up
Replies: 10
Views: 492

Re: All GPIO's dead but RPi 3B+ still works as normal - Follow-up

Soooo I figured it out for anybody interested. And I say this after frying another, and thankfully only one, GPIO pin on a different RPi board. I had used the external pull-up/current-limiting resistor configuration outlined above, and I was mysteriously still bouncing between 1's and 0's with the t...
by hawaiiankong
Fri Nov 08, 2019 7:58 pm
Forum: Troubleshooting
Topic: All GPIO's dead but RPi 3B+ still works as normal - Follow-up
Replies: 10
Views: 492

Re: All GPIO's dead but RPi 3B+ still works as normal - Follow-up

Potentially but so long as the closed button keeps the pin below its active high threshold it should be okay. For an external pull-up you can disable the active pull-up ... 3V3 >---------. .|. |_| 10K __ | GPIO <--|__|---{ 1K | |O |=== |O | 0V >---------' I had something slightly different in mind ...
by hawaiiankong
Fri Nov 08, 2019 6:11 pm
Forum: Troubleshooting
Topic: All GPIO's dead but RPi 3B+ still works as normal - Follow-up
Replies: 10
Views: 492

Re: All GPIO's dead but RPi 3B+ still works as normal - Follow-up

I'm not sure about that. I believe all GPIO pins default to inputs (unless they have specific default functions, which GPIO 21 does not). However, when hooking up a switch to a GPIO I always use external pull resistors and a current limiting resistor on the GPIO itself. That way even if the switch ...
by hawaiiankong
Fri Nov 08, 2019 5:23 pm
Forum: Troubleshooting
Topic: All GPIO's dead but RPi 3B+ still works as normal - Follow-up
Replies: 10
Views: 492

Re: All GPIO's dead but RPi 3B+ still works as normal - Follow-up

I just had a revelation, and I bet I know what happened! With that normally-closed button, the GPIO21 pin was pulled to ground at system start BEFORE THE SCRIPT WAS RUNNING . In other words, that GPIO pin was probably set as an output and being shorted to ground immediately when I powered up. The co...
by hawaiiankong
Fri Nov 08, 2019 4:49 pm
Forum: Troubleshooting
Topic: All GPIO's dead but RPi 3B+ still works as normal - Follow-up
Replies: 10
Views: 492

All GPIO's dead but RPi 3B+ still works as normal - Follow-up

Just wanted to follow up with an issue I had earlier this week, and thought maybe some RPi engineers could chime in with feedback. I searched feverishly and it seems that nobody's had this issue (or at least, asked about it). I was setting up to run RetroPie and wanted to install Reset and Shutdown ...
by hawaiiankong
Fri Nov 08, 2019 3:05 am
Forum: Troubleshooting
Topic: RPi Internal Pull-Up Resistors Not Functioning
Replies: 11
Views: 869

Re: RPi Internal Pull-Up Resistors Not Functioning

Update: I ran gpiotest and every single pin failed. I replaced my RPi 3B+ with an older 3B and ran the same test, and every pin passed. Also ran the previous test script and got 1's and 0's where they should be. I must have somehow fried the GPIO peripheral. I'm usually very careful too. Anybody wan...
by hawaiiankong
Fri Nov 08, 2019 1:14 am
Forum: Troubleshooting
Topic: RPi Internal Pull-Up Resistors Not Functioning
Replies: 11
Views: 869

Re: RPi Internal Pull-Up Resistors Not Functioning

What do you see if you just poll the input and print the state and press the button? import RPi.GPIO as GPIO import time import os GPIO.setmode(GPIO.BCM) GPIO.setup(21, GPIO.IN, pull_up_down=GPIO.PUD_UP) while True: print(GPIO.input(21)) time.sleep(0.5) I changed my code to poll GPIO21 (above). Wit...
by hawaiiankong
Thu Nov 07, 2019 8:35 pm
Forum: Troubleshooting
Topic: RPi Internal Pull-Up Resistors Not Functioning
Replies: 11
Views: 869

Re: RPi Internal Pull-Up Resistors Not Functioning

Not sure if this is part of the problem. I would use a pull-down if you are looking for a rising edge. The code is using a pull-up. The idea is that while the RPi is powered on, the pin remains grounded. When I press the normally-closed button, the pin gets pulled to 3.3V via the internal pull-up r...
by hawaiiankong
Thu Nov 07, 2019 5:40 pm
Forum: Troubleshooting
Topic: RPi Internal Pull-Up Resistors Not Functioning
Replies: 11
Views: 869

Re: RPi Internal Pull-Up Resistors Not Functioning

Your need something to stop your code from exiting, one way is a simple loop: import RPi.GPIO as GPIO import os import time GPIO.setmode(GPIO.BCM) GPIO.setup(21, GPIO.IN, pull_up_down=GPIO.PUD_UP) def psReset(channel): os.system("sudo shutdown -r now") GPIO.add_event_detect(21, GPIO.RISIN...
by hawaiiankong
Thu Nov 07, 2019 4:39 pm
Forum: Troubleshooting
Topic: RPi Internal Pull-Up Resistors Not Functioning
Replies: 11
Views: 869

Re: RPi Internal Pull-Up Resistors Not Functioning

Did you modify /boot/config.txt to enable anything like I2S? Does it work if you use another pin? No I haven't enabled any GPIO alternate modes, and yes I've tried GPIO24 (physical pin 18) and GPIO20 (pin 38) as well, and it does the same thing on both. So I don't suspect 3 random pins to be damage...
by hawaiiankong
Thu Nov 07, 2019 4:10 pm
Forum: Troubleshooting
Topic: RPi Internal Pull-Up Resistors Not Functioning
Replies: 11
Views: 869

RPi Internal Pull-Up Resistors Not Functioning

I've been working on this and googling furiously for almost a week, but have finally conceded defeat and wanted to reach out for help. I'm adding a Reset button that is normally closed, which is placed between GPIO21 (physical pin 40 on my RPI 3B+) and Ground. When I press the switch, it disconnects...

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