That sensor has an NPN output. That means, an NPN transistor pulls the output down if the sensor is triggered, otherwise the output is disconnected.
This is your current circuit.
simulate this circuit – Schematic created using CircuitLab
The lowpass filter is between the internal 100k pullup in the Raspberry Pi, and your capacitor. Your resistor ...
Here's information I found on the sensor:
some hookup information: http://pliki.aksotronik.pl/NJK-5002c.pdf
a demo using an Arduino: https://www.youtube.com/watch?v=Vc0LKeh_0FQ
previous SE question: How to replace a switch with a NJK-5002c hall sensor?
The interesting tidbit in the SE question is:
The NJK-5002c doesn't have a lot of documentation, but I'...
I've had similar problems with similar speed sensors on trucks. The problem might be the cable itself acting as antenna and picking up radiated noise. Check the signal with a scope, are you picking up stray spikes etc along with the pulse train?
The first thing I would try is to replace the cable with a shielded version and then obviously also try to keep it ...
Your proposal has very little use in practical implementation. Coming from industrial world of PLC it would translate as:
int a0value = digitalRead(GPIOA0);
digitalWrite( GPIOB0, a0value );
At each main sweep cycle you do read peripheral inputs and you copy them into temporary buffer a0value, at the very next moment you do copy temporary output values ...
are there typically facilities for "real-time" copying/buffering an input pin's state to another (output) pin?
Depends on your latency constraints. The order of magnitude (ms, us, ns) will determine which category of technology is available to you at which price point.
But vaguely, "yes".
This is also highly dependent on your ...
This is another in your series of questions on this topic and it seems you are still very confused about CMOS input impedance. It's very simple:
If the pin is configured as an input it will have a very high input impedance, typically > 1 MΩ as is characteristic of any CMOS input. Table 18 of the datasheet shows that the input leakage current is < 0.5 ...