From e5f06559e6762b00e36a66901ba092676cd8e019 Mon Sep 17 00:00:00 2001
From: ernitron <ernitron@gmail.com>
Date: Mon, 31 Oct 2016 10:54:44 +0100
Subject: [PATCH] esp8266/modules: Fix negative temperature in ds18x20 driver.

---
 esp8266/modules/ds18x20.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/esp8266/modules/ds18x20.py b/esp8266/modules/ds18x20.py
index eb22e2ae30..fc53048f8e 100644
--- a/esp8266/modules/ds18x20.py
+++ b/esp8266/modules/ds18x20.py
@@ -43,4 +43,7 @@ class DS18X20:
                 t = buf[0] >> 1
             return t - 0.25 + (buf[7] - buf[6]) / buf[7]
         else:
-            return (buf[1] << 8 | buf[0]) / 16
+            t = buf[1] << 8 | buf[0]
+            if t & 0x8000: # sign bit set
+                t = -((t ^ 0xffff) + 1)
+            return t / 16