I have few switches connected to Raspberry Pi inputs.
Internal pull up resistors are enabled.
When I connect pin to the ground Raspberry Pi behave fine - pin state is low.
However when I disconnect the pin from the ground it randomly change the state every few seconds.
I have tried to add external 10k pull up resistor but it haven't worked.
Pull up resistor is connected near Raspberry Pi.
Switch is connected by 7 meters UTP 5e cable.
I use pi4j library.
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Please add a photo of the connections. An external 10k resistor should be enough to stop the input floating. A listing of the software will also be useful. – joan Oct 5 '19 at 19:41
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I have updated description and added picture – mariusz2108 Oct 5 '19 at 19:55
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Perhaps the 7 metres of cable is too much for a 10 k resistor. As an experiment do you get a problem if you connect to GPIO 2 or 3 (they have 1k8 pulls to 3V3 fitted). – joan Oct 5 '19 at 20:12
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related if not dupe: raspberrypi.stackexchange.com/q/57951/19949 and raspberrypi.stackexchange.com/q/93834/19949 (the length of the cable - now edited into the question - might be an issue... try decreasing the pull-up) – Ghanima♦ Oct 5 '19 at 20:13
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Actually I have problem with pins 4,5,13,14, and 29. I couldn't find Raspberry Pi 3B+ electric schema – mariusz2108 Oct 5 '19 at 20:15
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If you are actually using GPIO0 (pin 27) this is actually SDA.0 which is used to control HATs and is marked reserved on official documentation.
I believe on newer Pi models this I²C bus is also connected to on-board extenders so is used for other purposes, although this is not documented, expect the voltage on this pin to change unexpectedly.
Use any ot the other pins (and a low impedance circuit).
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Actually I have problem with GPIO pins 4,5,13,14, and 29 of 3B+. I couldn't find Raspberry Pi 3B+ electric schema – mariusz2108 Oct 6 '19 at 9:25
