Suppress EMI noise on water flow sensor by filtering short pulses

Software/MainBoard/rust/src/hal/water.rs

@@ -53,6 +53,9 @@ impl<'a> TankSensor<'a> {
         let one_wire_bus = OneWire::new(one_wire_pin, false);
 
         pcnt1.set_high_limit(Some(i16::MAX))?;
+        // Reject pulses shorter than ~12.8 µs (1023 APB cycles @ 80 MHz) to suppress EMI noise
+        // on the sensor cable. Real flow pulses are in the millisecond range.
+        pcnt1.set_filter(Some(1023)).unwrap();
 
         let ch0 = &pcnt1.channel0;
         ch0.set_edge_signal(flow_sensor.peripheral_input());