Reduced fan tacho reporting latcency for ATE

1 files changed, 13 insertions, 11 deletions

diff --git a/src/Fans/LocalFan.cpp b/src/Fans/LocalFan.cpp
index 44fcd9da..7bba31a4 100644
--- a/src/Fans/LocalFan.cpp
+++ b/src/Fans/LocalFan.cpp
@@ -161,17 +161,6 @@ void LocalFan::InternalRefresh() noexcept
 
 	SetHardwarePwm(reqVal);
 	lastVal = reqVal;
-
-	if (tachoPort.IsValid())
-	{
-		// The ISR sets fanInterval to the number of step interrupt clocks it took to get fanMaxInterruptCount interrupts.
-		// We get 2 tacho pulses per revolution, hence 2 interrupts per revolution.
-		// When the fan stops, we get no interrupts and fanInterval stops getting updated. We must recognise this and return zero.
-		const float rpm = (fanInterval != 0 && StepTimer::GetTimerTicks() - fanLastResetTime < 3 * StepTimer::StepClockRate)	// if we have a reading and it is less than 3 seconds old
-						  ? (StepTimer::StepClockRate * fanMaxInterruptCount * (60/2))/fanInterval		// then calculate RPM assuming 2 interrupts per rev
-						  : 0;																			// else assume fan is off or tacho not connected
-		SetLastRpm(rpm);
-	}
 }
 
 GCodeResult LocalFan::Refresh(const StringRef& reply) noexcept
@@ -215,6 +204,19 @@ bool LocalFan::AssignPorts(const char *pinNames, const StringRef& reply) noexcep
 	return true;
 }
 
+// Tacho support
+int32_t LocalFan::GetRPM() const noexcept
+{
+	// The ISR sets fanInterval to the number of step interrupt clocks it took to get fanMaxInterruptCount interrupts.
+	// We get 2 tacho pulses per revolution, hence 2 interrupts per revolution.
+	// When the fan stops, we get no interrupts and fanInterval stops getting updated. We must recognise this and return zero.
+	return (!tachoPort.IsValid())
+			? -1																			// we return -1 if there is no tacho configured
+			: (fanInterval != 0 && StepTimer::GetTimerTicks() - fanLastResetTime < 3 * StepTimer::StepClockRate)	// if we have a reading and it is less than 3 seconds old
+			  ? (StepTimer::StepClockRate * fanMaxInterruptCount * (60/2))/fanInterval		// then calculate RPM assuming 2 interrupts per rev
+			  : 0;																			// else assume fan is off or tacho not connected
+}
+
 void LocalFan::Interrupt() noexcept
 {
 	++fanInterruptCount;