HTU20D(F) RH/T SENSOR IC

Digital Relative Humidity sensor with Temperature output

9/2015

Page 13

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10

11

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16

17

18

S

1

0

0

0

0

0

0

0

ACK

1

1

1

1

0

1

0

1

ACK

I²C address + write

Command (see table p.9)

19

20

21

22

23

24

25

26

27

Measurement

S

1

0

0

0

0

0

0

1

NACK

measuring

I²C address + read

19

20

21

22

23

24

25

26

27

Measurement

S

1

0

0

0

0

0

0

1

ACK

continue measuring

I²C address + read

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

0

1

1

1

1

1

0

0

ACK

1

0

0

0

0

0

1

0

ACK

Data (MSB)

Data (LSB)

Status

46

47

48

49

50

51

52

53

54

1

0

0

1

0

1

1

1

NACK

P

Checksum

No Hold Master communication sequence

Grey blocks are controlled by HTU20D(F) sensor.

For Hold Master sequence, bit 45 may be changed to NACK followed by a stop condition to omit checksum

transmission.

For No Hold Master sequence, if measurement is not completed upon

“read” command, sensor does not provide

ACK on bit 27 (more of these iterations are possible). If bit 45 is changed to NACK followed by stop condition,

checksum transmission is omitted.

= ‘0111’1100’1000’0000 (0x7C80). For the calculation of

physical values status bits must be set to ‘0’. Refer to “Conversion of signal outputs” section p.16.

The maximum duration for measurement depends on the type of measurement and resolution chosen. Maximum

values shall be chosen for the communication planning of the MCU. Refer to the table p.4 and p.6 regarding

measuring time specifications.

I²C communication allows for repeated start conditions without closing prior sequence with stop condition.



Soft reset

This command is used for rebooting the HTU20D(F) sensor switching the power off and on again. Upon reception

of this command, the HTU20D(F) sensor system reinitializes and starts operation according to the default settings

with the exception of the heater bit in the user register. The soft reset takes less than 15ms.

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18

S

1

0

0

0

0

0

0

0

ACK

1

1

1

1

1

1

1

0

ACK

P

I²C address + write

Soft Reset Command

Grey blocks are controlled by HTU20D(F) sensor.