From 783a21d88d8f8684322a5e2225f0c0b990e6b7a9 Mon Sep 17 00:00:00 2001
From: Blaz Kristan <blaz@kristan-sp.si>
Date: Sun, 3 Oct 2021 14:00:29 +0200
Subject: [PATCH] Fix for incorrect RPM reported.

---
 usermods/PWM_fan/usermod_PWM_fan.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/usermods/PWM_fan/usermod_PWM_fan.h b/usermods/PWM_fan/usermod_PWM_fan.h
index 624534b1..97e7cd12 100644
--- a/usermods/PWM_fan/usermod_PWM_fan.h
+++ b/usermods/PWM_fan/usermod_PWM_fan.h
@@ -80,7 +80,8 @@ class PWMFanUsermod : public Usermod {
       // detach interrupt while calculating rpm
       detachInterrupt(digitalPinToInterrupt(tachoPin)); 
       // calculate rpm
-      last_rpm = counter_rpm * (60 / numberOfInterrupsInOneSingleRotation);
+      last_rpm = (counter_rpm * 60) / numberOfInterrupsInOneSingleRotation;
+      last_rpm /= tachoUpdateSec;
       // reset counter
       counter_rpm = 0; 
       // store milliseconds when tacho was measured the last time