proper fix for flex temp sensing

firmware/CHANGELOG.md

@@ -44,6 +44,7 @@ or
  - Improve performance with Lua CAN reception of a high volume of frames
  - Displayed units in TunerStudio change when switching between volume vs. mass injector flow modes #42
  - Make Toyota "3 Tooth Cam" decoder more robust #382
+ - Flex sensor-derived fuel temperature indication works properly
 
 ## December 2023 Release
 

firmware/init/sensor/init_flex.cpp

@@ -15,14 +15,8 @@ static Biquad flexTempFilter;
 static Timer flexFreq, flexPulse;
 
 static void flexCallback(efitick_t nowNt, bool value) {
-	if (!value) {
-		float frequency = 1 / flexFreq.getElapsedSecondsAndReset(nowNt);
-		flexSensor.postRawValue(frequency, nowNt);
-
-		// Start timing pulse width on rising edge
-		flexPulse.reset(nowNt);
-	} else {
-		// End pulse timing on falling edge
+	if (value) {
+		// End pulse timing on rising edge
 		float pulseWidthUs = flexPulse.getElapsedUs(nowNt);
 
 		if (pulseWidthUs < 900) {
@@ -36,6 +30,12 @@ static void flexCallback(efitick_t nowNt, bool value) {
 			tempC = flexTempFilter.filter(tempC);
 			flexFuelTemp.setValidValue(tempC, nowNt);
 		}
+	} else {
+		float frequency = 1 / flexFreq.getElapsedSecondsAndReset(nowNt);
+		flexSensor.postRawValue(frequency, nowNt);
+
+		// Start timing pulse width on falling edge
+		flexPulse.reset(nowNt);
 	}
 }