From a5c79214e3842a6594c575aedec4f520375e4be8 Mon Sep 17 00:00:00 2001
From: Waldemar Porscha <wp@porscha.eu>
Date: Thu, 24 Aug 2023 10:43:21 +0200
Subject: [PATCH] Improved float16ToPayload correction

---
 src/knx/dptconvert.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/knx/dptconvert.cpp b/src/knx/dptconvert.cpp
index fc6a932..1e479b2 100644
--- a/src/knx/dptconvert.cpp
+++ b/src/knx/dptconvert.cpp
@@ -1753,6 +1753,12 @@ void float16ToPayload(uint8_t* payload, size_t payload_length, int index, double
         exponent = ceil(log2(value + 1.0) - 11.0);
     
     short mantissa = roundf(value / (1 << exponent));
+    // above calculation causes mantissa overflow for values of the form 2^n, where n>11
+    if (mantissa >= 0x800)
+    {
+        exponent++;
+        mantissa = roundf(value / (1 << exponent));
+    }
 
     if (wasNegative)
         mantissa *= -1;