HTU20D(F) RH/T SENSOR IC

Digital Relative Humidity sensor with Temperature output

9/2015

Page 11

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Timing diagram for digital input/output pads

DATA directions are seen from the HTU20D(F) sensor. DATA line in bold is controlled by the sensor. DATA valid

read time is triggered by falling edge of anterior toggle.

COMMUNICATION PROTOCOL WITH HTU20D(F) SENSOR

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Start-up sensor

The HTU20D(F) sensor requires a voltage supply between 1.5V and 3.6V. After power up, the device needs at

most 15ms while SCK is high for reaching idle state (sleep mode), i.e to be ready accepting commands from the

MCU. No command should be sent before that time. Soft reset is recommended at start, refer p.13.

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Start sequence (S)

To initiate transmission, a start bit has to be issued. It consists of a lowering of the DATA line

while SCK is high followed by lowering SCK.

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Stop sequence (P)

To stop transmission, a stop bit has to be issued. It consists of a heightening of the DATA line

while SCK is high preceded by a heightening of the SCK.

HTU20D(F) SENSOR LIST OF COMMANDS AND REGISTER ADRESSES

For sample source code, please request to humidity.application@te.com.

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Sending a command

After sending the start condition, the subsequent I²C header consist of a 7-bit I²C device address 0x40 and a DATA

direction bit (‘0’ for Write access :0x80). The HTU20D(F) sensor indicates the proper reception of a byte by pulling

(0xE3 for temperature, 0xE5 for relative humidity), the MCU must wait for the measurement to complete. The basic

commands are given in the table below: