From b0f0c8d8424182ac7c1d1431f6634ca520b7fd3b Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Sun, 8 Nov 2020 21:57:01 +1100
Subject: [PATCH] Filter: use calc_lowpass_alpha_dt()

---
 libraries/Filter/LowPassFilter.cpp | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/libraries/Filter/LowPassFilter.cpp b/libraries/Filter/LowPassFilter.cpp
index 282ca5a3bf..25c756cf8b 100644
--- a/libraries/Filter/LowPassFilter.cpp
+++ b/libraries/Filter/LowPassFilter.cpp
@@ -38,12 +38,10 @@ T DigitalLPF<T>::apply(const T &sample) {
 
 template <class T>
 void DigitalLPF<T>::compute_alpha(float sample_freq, float cutoff_freq) {
-    if (cutoff_freq <= 0.0f || sample_freq <= 0.0f) {
-        alpha = 1.0;
+    if (sample_freq <= 0) {
+        alpha = 1;
     } else {
-        float dt = 1.0/sample_freq;
-        float rc = 1.0f/(M_2PI*cutoff_freq);
-        alpha = constrain_float(dt/(dt+rc), 0.0f, 1.0f);
+        alpha = calc_lowpass_alpha_dt(1.0/sample_freq, cutoff_freq);
     }
 }