HS401x Datasheet

R36DS0023EU0103 Rev.1.03

Jun 6, 2022

Page 16

The registers used to enable the Alert feature and the temperature / humidity thresholds are shown in Table 11.

When the Alert feature is enabled for either humidity or temperature in Periodic Measurement Mode, an

additional status byte will precede the measurement values. The format of the bits are returned from the HS401x

sensor when any Alert is enabled (as shown in Figure 20). The meaning of the Alert status bits are defined in

Table 8.

Table 8. Alert Status Bits

Status Bit

Meaning

TH

High (0b1) if the Temperature High Alert is triggered

TL

High (0b1) if the Temperature Low Alert is triggered

HH

High (0b1) if the Humidity High Alert is triggered

HL

High (0b1) if the Humidity Low Alert is triggered

Figure 20. Data Returned from HS401x when the Alert Feature is Enabled in Periodic Measurement Mode

4.7

Accessing Configurable HS401x Registers

The HS401x measurement settings can be changed by accessing the appropriate configuration registers and

altering their values. This can be done by issuing a Write Register command. A Read Register command is also

available to read the configuration register values. These commands will be described in this section, and the

configuration registers and settings will be described in section 4.8.

While accessing specific configuration bits in any register, all the other bits in that register must be left

unchanged. To write a specific bit/bits in a register, the process is as follows:

1.

Read the entire configuration register using the sequence described in section 4.7.1.

2.

Mask the register such that only the required bits are changed, according to the configuration parameters in

section 4.8.

3.

Write the new register back to the appropriate address using the Write Register command sequence

described in section 4.7.2.

All configuration registers will be reset to their default values if the power supply to the chip is cutoff.