Hi guys,
I've been working on a flowmeter input circuit to interface with a reed switch based flow meter. The meter is run off 12VDC so I've added a divider with a fairly hard pull up (for noise immunity?).
Does this look like I'm on the right track?
Also do I need to pull down after the 74HC14 Schmitt Trigger, the reason I put this here is for noise immunity as well?
I went pull-down as its an inverter if that makes sense or should i have both sides pulled up?
The main thing I want to achieve is noise immunity and accurate pulse counting, the Pulse_In signal is connected to D2 of an Arduino Nano and I'm using interrupts to count pulses for a totalizer.
The reed switch in the pulse meter bounces a bit and from my tests the worse bounce I've seen is just under 100us on my scope.
The absolute maximum frequency I will be running is around 500Hz with most situations under 120Hz.
I'd appreciate any feedback on my current design.
Cheers guys.