Data Sheet

ams Datasheet Page 19
[v1-00] 2016-Dec-23 Document Feedback
CCS811 − Application Register Overview
ENV_DATA (Environment Data) Register (0x05)
A multi-byte register that can be written with the current
Humidity and Temperature values if known.
Relative Humidity
Figure 16:
Relative Humidity Fields and Byte Order
Humidity is stored as an unsigned 16 bits in 1/512%RH. The
default value is 50% = 0x64, 0x00. As an example 48.5%
humidity would be 0x61, 0x00.
Temperature
Figure 17:
Temperature Fields and Byte Order
Temperature is stored as an unsigned 16 bits integer in 1/512
degrees; there is an offset: 0 maps to -25°C. The default value is
25°C = 0x64, 0x00. As an example 23.5% temperature would be
0x61, 0x00.
The internal algorithm uses these values (or default values if
not set by the application) to compensate for changes in
relative humidity and ambient temperature.
Byte 0 Byte 1
Humidity High Byte Humidity Low Byte
7654321076543 2 1 0
64 32 1684211/21/41/81/161/321/641/1281/2561/512
Humidity % Humidity % Fraction
Byte 2 Byte 3
Temperature High Byte Temperature Low Byte
76543210 7 6 5 4 3 2 1 0
64 32 16 8 4 2 1 1/2 1/4 1/8 1/16 1/32 1/64 1/128 1/256 1/512
Temperature 25°C Temperature 25°C Fraction