HS401x Datasheet

R36DS0023EU0103 Rev.1.03

Jun 6, 2022

Page 20

Setting

Register

Address

(HEX)

Bits

Description

Reset Threshold for

Relative Humidity High

Alert

0x0E, 0x0D

<13:0>

Registers 0x0E, 0x0D set the threshold for when the “RH High” alert

condition is reset. After the alert is triggered, it will only be reset after the

measured RH goes below the value in this register.

The humidity used for the threshold is composed of 14-bits as follows:

This 14-bit value is converted into a humidity threshold using the same

conversion equation shown in section 4.4.3.

Trigger Threshold for

Relative Humidity Low

Alert

0x12, 0x11

<13:0>

Registers 0x12, 0x11 set the threshold for when the “RH Low” alert is

triggered. When the measured RH goes below the value in this register,

the Alert pin will be triggered.

The humidity used for the threshold is composed of 14-bits as follows:

This 14-bit value is converted into a humidity threshold using the same

conversion equation shown in section 4.4.3.

Reset Threshold for

Relative Humidity Low

Alert

0x14, 0x13

<13:0>

Registers 0x14, 0x13 sets the threshold for when the “RH Low” alert

condition is reset. After the alert is triggered, it will only be reset after the

measured RH goes above the value in this register.

The humidity used for the threshold is composed of 14-bits as follows:

This 14-bit value is converted into a humidity threshold using the same

conversion equation shown in section 4.4.3.

4.9

Reading the Sensor ID Number

The sensor ID is a 32-bit number that can be used to identify a given device. Each sensor has a unique ID that

can be used for traceability. The sequence to read the sensor ID is as follows:

1.

a Read Sensor ID command by sending the command 0xD7.

2.

held low by the sensor while it retrieves the ID from internal memory to prevent data corruption. The sensor

takes approximately 10µs to retrieve the ID from internal memory.

3.

Once the request is completed by the HS401x series sensor, the SCL line is released and the chip waits for

the SCL clock signal to send the results. The sensor will then transmit the 4-byte sensor ID on the bus for

the master to capture, MSB first.

The command sequence to read the sensor ID is displayed in Figure 23.

0

0

0

0

0

1

0

1

1

0

0

0

0

0

0

0

Register 0x0E

Register 0x0D

0's

Reset Threshold [13:8]

Reset Threshold [7:0]

0

0

0

0

0

1

0

1

1

0

0

0

0

0

0

0

Register 0x12

Register 0x11

0's

Trigger Threshold [13:8]

Trigger Threshold [7:0]

0

0

0

0

0

1

0

1

1

0

0

0

0

0

0

0

0's

Reset Threshold [13:8]

Reset Threshold [7:0]

Register 0x14

Register 0x13