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Version 2 – August 2016

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5.10 Communication Data Sequences

1

2

3

4

5

6

7

8

9

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

S

P

SHTW2 measuring

1 1 1 0 0 0 0 0

0 1 0 1 1 1 0 0

0 0 1 0 0 1 0 0

Measurement command MSB

Measurement command LSB

Measurement in progress

29 30 31 32 33 34 35 36 37 38 39

40 41 42 43 44 45 46 47 48 49

S

SHTW2 in idle

state

S

1 1 1 0 0 0 0 1

1 1 1 0 0 0 0 1

while meas. is in prog. (polling)

measurement cont’d

measurement

completed

29 30 31 32 33 34 35 36 37 38

S

SHTW2 measuring,

SCL line pulled low

1 1 1 0 0 0 0 1

while meas. is in progress

measurement continued

50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76

1 0 1 0 0 0 0 1

0 0 1 1 0 0 1 1

0 0 0 1 1 1 0 0

Humidity MSB

Humidity LSB

Humidity CRC checksum

77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104

P

0 1 1 0 0 1 0 0

1 0 0 0 1 0 1 1

1 1 0 0 0 1 1 1

Temperature MSB

Temperature LSB

Temperature CRC checksum

Figure 7 Communication sequence for starting a measurement and reading measurement results displaying both clock stretching options.

The numerical example corresponds to a read humidity-first command with clock stretching enabled. The physical values of the transmitted

measurement results are 65.6 %RH and 23.7 °C. Clear blocks are controlled by the microcontroller, grey blocks by the SHTW2.

1

2

3

4

5

6

7

8

9

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

S

P

1 1 1 0 0 0 0 0

1 0 0 0 0 0 0 0

0 1 0 1 1 1 0 1

Command MSB

Command LSB

Figure 8 Command access communication sequence. The example shows a soft reset command. Clear blocks are controlled by the

microcontroller, grey blocks by the SHTW2.

clock stretching

disabled

clock

stretching enabled