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Version 1.1 – April 2021

14/22

3.8 Low Power operation

To enable use-cases with a constrained power-budget, the SCD4x features a low power periodic measurement mode with signal

update interval of approximately 30 seconds. While the low power mode saves power and reduces self-heating of the sensor,

the low power periodic measurement mode has a longer response time.

The low power periodic measurement mode is initiated and read-out in a similar manner as the default periodic measurement.

Please consult chapter 3.5.2 for further instructions. To avoid receiving a NACK in case the result of a subsequent measurement

is not ready yet, the get_data_ready_status command can be used to check whether new measurement data is available for

read-out.

3.8.1

start_low_power_periodic_measurement

Description: start low power periodic measurement, signal update interval is approximately 30 seconds.

Write

(hexadecimal)

Input parameter: -

Response parameter: -

Max. command

duration [ms]

length [bytes]

signal conversion

length [bytes]

signal conversion

0x21ac

-

-

-

-

not applicable

Example: start low power periodic measurement

Write

0x21ac

(hexadecimal)

Command

3.8.2

get_data_ready_status

Write

(hexadecimal)

Input parameter: -

Response parameter: data ready status

Max. command

duration [ms]

length [bytes]

signal conversion

length

[bytes]

signal conversion

0xe4b8

-

-

3

If the least significant 11 bits of

word[0] are 0 → data not ready

else → data ready for read-out

1

Example: read data ready status: data not ready

Write

0xe4b8

(hexadecimal)

Command

Wait

1 ms

command execution time

Response

0x8000

0xa2

(hexadecimal)

Least significant 11 bits are 0 → data not ready

CRC of 0x8000