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Version 3.3 – November 2024

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3.3.13 Alternative FRC persistence

When using FRC, the read and write offset value commands can be used to persist only the offset value used

for FRC. All other settings, like the binary gas index must be set with the separate commands.

Command

Command code

(hex)

Consecutive read /

argument

Description

Read offset value

command

0x370A

16 bits

Returns a single value with the most

significant 16 bits of the offset value.

Write offset value

command

0x3608

16 bits

Expects the most significant 16 bits of

the offset value as an I2C command

argument.

Note that this is not suitable for ASC in combination with sleep mode, because the least significant bits of the

offset value are lost.

3.3.14 Sleep mode

In sleep mode the sensor uses the minimum amount of current. The mode can be entered when no other

command is running. This mode is particularly useful for battery operated devices.

Implement and test the Sensor state retention sequence as described in section 3.3.12 before implementing the

sleep sequence.

For the sensor state retention, a sleep mode is equivalent to a power cycle. Follow the procedure in section

3.3.13 to keep settings and FRC and ASC values.

Since the noise filter state is not part of the state retention it cannot be used in combination with the sleep

mode.

In sleep mode the sensor cannot be soft reset.

Command

Command code

(hex)

Consecutive

read

Description

Enter Sleep mode

0x3677

NA

The sleep command can be sent anytime,

whenever no other command is running.

Exit Sleep mode

NA

NA

The sensor exits the sleep mode when it

receives the valid I2C address and a write bit

(‘0’).

Note that the I2C address is not acknowledged.

It is possible to poll the sensor to see whether

the sensor has received the address and has

woken up. This takes maximum 12ms.