ESP8266 Community Forum

- Tue Mar 08, 2016 12:29 pm #42699 Hi

I built this project: http://www.instructables.com/id/Low-cos ... /?ALLSTEPS
I works, but when I try to measure a negative temperature I only get -0.125C. But the temperature should be lower.

Regards
Florian

- Tue Mar 08, 2016 5:37 pm #42709 READ the DS18B20 Data pdf
get the raw temp -- MSB LSB
save sign bit MSB hi Bit then logical and MSB,LSB with 7FF = RESULT assuming using 11 bits

if sign bit =1 then Complement result and add 1 = 2's complemented RESULT
now complemented RESULT * .0625 should = negative temperature
else
RESULT = RESULT * .0625 should = positive temperature

You figure out the actual code needed....