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version 1.0 – December 2021

15/22

Relative Humidity

Temperature

Value / %

Hex. code

Value / °C

Hex. code

Conversion into ticks

RH/ticks=RH/%×

65'535

100

T/ticks=(T/°C + 45)×

65'535

175

Default

50

0x80 0x00 + CRC 0xA2

25

0x66 0x66 + CRC 0x93

Minimum

0

0x00 0x00 + CRC 0x81

−45

0x00 0x00 + CRC 0x81

Maximum

100

0xFF 0xFF + CRC 0xAC

130

0xFF 0xFF + CRC 0xAC

Table 12 Conversion of relative humidity in % and temperature in °C into ticks as the input parameters of the measurement command. Note:

minimum and maximum values do not reflect the range of conditions for which the humidity compensation feature has been optimized (see

Table 4).

Byte number

Description

Value

0, 1

two bytes

u16 unsigned integer directly provides the raw signal

SRAW_VOC in ticks which is proportional to the logarithm of the

resistance of the sensing element.

2

CRC byte for bytes 0, 1

–

3, 4

two bytes

u16 unsigned integer directly provides the raw signal

SRAW_NOX in ticks which is proportional to the logarithm of the

resistance of the sensing element.

5

CRC byte for bytes 3, 4

–

Built-in Self-Test

Command

Command hex. code

Description

sgp41_execute_self_test

0x28 0x0E

This command triggers the built-in self-test checking for integrity

of both hotplate and MOX material and returns the result of this

test as 2 bytes (+ 1 CRC byte).