esp8266/modules: Fix negative temperature in ds18x20 driver.

e5f06559 · ernitron · Damien George · 10bde693 · e5f06559
Commit e5f06559 authored Oct 31, 2016 by ernitron Committed by Damien George Nov 02, 2016
Show whitespace changes
Inline Side-by-side

Showing with 4 additions and 1 deletion

esp8266/modules/ds18x20.py esp8266/modules/ds18x20.py +4 -1

No files found.
--- 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