Setup: I have a Xenon measuring a paddle wheel flow meter (3 wires: pos, neg, pulse) that sends a pulse while water is flowing. When flow stops, there is a timer that when complete, puts the Xenon into SLEEP_MODE_DEEP. I want to wake the Xenon when flow starts again, so I have the pulse wire from the flow meter into D8. The pulse signal is either LOW or HIGH. The problem is that sometimes the flow meter gets stuck in a position that stays HIGH. So when the Xenon goes into deep sleep, it just immediately wakes back up again. If the flow meter is in a LOW state, then all is good.
Any ideas on how to implement a RISING signal to D8 if the flow meter pulse signal is at an uncontrollable HIGH or LOW state? I’ve experimented with the thought of an assortment of MOSFET switches and JK flip flops. But both get me to the same conclusion. I pretty much need:
if FlowMeterSignal = HIGH or LOW, D8 = LOW until FlowMeterSignal changes state (LOW to HIGH or HIGH to LOW). The Xenon is in deep sleep when the flow meter signal is supposed to change state, so the switching will have to be external to the Xenon capabilities.