HTU20P Просмотр технического описания (PDF) - Unspecified

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HTU20P

Digital Relative Humidity sensor with Temperature output

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HTU21D(F) Sensor

Digital Relative Humidity sensor with Temperature output

 User register

The content of user register is described in the table below. Reserved bits must not be changed and default

values of respective reserved bits may change over time without prior notice. Therefore, for any writing to user

register, default values of reserved bits must be read first.

The “End of Battery” alert/status is activated when the battery power falls below 2.25V.

The heater is intended to be used for functionality diagnosis: relative humidity drops upon rising temperature.

The heater consumes about 5.5mW and provides a temperature increase of about 0.5-1.5°C.

OTP reload is a safety feature and load the entire OTP settings to the register, with the exception of the heater

bit, before every measurement. This feature is disabled per default and it is not recommended for use. Please

use soft reset instead as it contains OTP reload.

Bit

#Bits

Description/Coding

7,0

2

Measurement resolution

Bit 7 Bit 0 RH

0

0 12 bits

0

1

8 bits

1

0 10 bits

1

1 11 bits

6

1

Status: End of Battery(1)

‘0’: VDD>2.25V

‘1’: VDD<2.25V

3, 4, 5

3

Reserved

2

1

Enable on-chip heater

1

1

Disable OTP reload

(1) This status bit is updated after each measurement

Temp

14 bits

12 bits

13 bits

11 bits

Default

‘00’

‘0’

‘0’

‘0’

‘1’

Cut-off value for “End of Battery” signal may vary by ±0.1V.

Reserved bits must not be changed.

OTP reload active loads default settings after each time a measurement command is issued.

 I²C communication reading and writing the user register example

In this example, the resolution is set to 8 bits / 12 bits (for RH/Temp) from default configuration.

12345678

9 10 11 12 13 14 15 16 17

18

S 1 0 0 0 0 0 0 0 ACK 1 1 1 0 0 1 1 1 ACK

I²C address + write

Read Register Command

19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

S 1 0 0 0 0 0 0 1 ACK 0 0 0 0 0 0 1 0 NACK

I²C address + read

Register content

37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54

S 1 0 0 0 0 0 0 0 ACK 1 1 1 0 0 1 1 0 ACK

I²C address + write

Write Register Command

55 56 57 58 59 60 61 62 63

0 0 0 0 0 0 1 1 ACK P

Register Content to be written

Grey blocks are controlled by HTU21D(F) sensor.

HPC199_3 HTU21D(F) Sensor Datasheet

www.meas-spec.com

13/21

October 2013

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