Troubleshooting • some observation on GPIO voltage

Hello,

I have been working on Pi's for quiet a while, but mostly on the software part. Recently i had a chance to hoot it up with an oscilloscope(like a grow-up who never got play with his favorite toy during his child hood). and got baffled when i observed over it.
Below are my observations out of curiosity, to explore / learn to operate oscilloscope options, with triggers etc, I hooked one of the GPIO pins to it.1. [ over GPIO4 ] wanted to see if i was able to measure something on a basic level for the first time. Multimeter showed ~3.2v while oscilloscope showed something around ~0.336v (multimeter and scope's probe is connected at the same time over the same pin)a. How wrongly am i taking the measurement ? (as a noob, hopefully im not taking the measurement the right way)
b. Why is there a shift on voltage when i turn off the multimeter ?

2. [ over GPIO4 ] on a diff instance, i wanted this pin to turn on a hat after pi's been booted up. but when i left the multimeter hook up during pi's restart i observed that once the pi's gets power (or say the moment its connected to the wall socket, or to put it in a diff way-before it boots completely) i could see the GPIO spitting out 3.x volts (The hat requires to be active high for 3 seconds).
Is it normal that this pin being active high even before complete boot up ?

Statistics: Posted by tesarect — Mon Dec 16, 2024 9:04 am — Replies 2 — Views 58

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