From 6294e39746e7cbc95477e44c128959b0178700d3 Mon Sep 17 00:00:00 2001
From: "D.R.racer" <drracer@drracer.eu>
Date: Fri, 22 Oct 2021 13:46:01 +0200
Subject: [PATCH] Avoid repeated writes into the shift register

May reduce flickering of LEDs on some boards
---
 src/modules/leds.cpp | 6 ++++--
 src/modules/leds.h   | 3 +++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/modules/leds.cpp b/src/modules/leds.cpp
index fc7ac97..5d58415 100644
--- a/src/modules/leds.cpp
+++ b/src/modules/leds.cpp
@@ -49,8 +49,10 @@ void LEDs::Step() {
         result <<= 1;
         result |= leds[i].Step(oddPeriod);
     }
-
-    hal::shr16::shr16.SetLED(result);
+    if (result != cachedState) {
+        hal::shr16::shr16.SetLED(result);
+        cachedState = result;
+    }
 }
 
 } // namespace leds
diff --git a/src/modules/leds.h b/src/modules/leds.h
index 93a2e82..c2afcb0 100644
--- a/src/modules/leds.h
+++ b/src/modules/leds.h
@@ -130,6 +130,9 @@ private:
     /// [8] - green LED slot 4
     /// [9] - red LED slot 4
     LED leds[ledPairs * 2];
+
+    /// Cache for avoiding duplicit writes into the shift registers (may reduce LED flickering on some boards)
+    uint16_t cachedState = 0;
 };
 
 /// The one and only instance of FINDA in the FW