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Modifications reserved |Data subject to change without notice | Printed in Germany

Document number: BST-BME688-DS000-03 Revision_1.3 022024

5.3.4.4 Gas Sensor heater-on time in parallel mode -- gas_wait_x & gas_wait_shared

Referring to 3.5.4, total heater-on time depends on number of TPHG sequence, time taken for TPHG measurement and wait

phase of each TPHG sequence. gas_wait_x<7:0> sets number of times TPHG sequence needs to be repeated.

The number of TPHG sub-measurement sequences within the one Gas conversion for one target temperature resistance is

defined by gas_wait_X(7:0) settings. The duration of measurement is calculated as follows: Duration = gas_wait_X × (wait

time defined by gas_wait_shared + TTPHG_duration)

Heater step

Address

Content

Description

0...9

gas_wait_x

x is from 0 to 9

0x64…0x6D

gas_wait_x<7:0>

x is from 0 to 9

255 values with

1 LSB corresponds to 1 TPHG

sequence, all zeros means

gas_wait_shared is fully

skipped and one TPHG

sequence is executed.

gas_wait_shared<7:0> sets wait time before each TPHG measurement sequence with duration as configured below. This

is common for the whole gas measurement sequence in parallel mode.

Address

Content<bit position>

Description

gas_wait_shared

0x6E

gas_wait_shared<5:0>

64 timer values with 0.477ms step sizes, all zeros

means no wait.

gas_wait_shared=0x00 is treated

as if gas_wait_shared=0x01.

gas_wait_shared

<7:6>

Gas sensor wait time multiplication factor

5.3.4.5 Heater off - heat_off

Address

Content<bit

position>

Description

ctrl_gas_0

0x70

heat_off <3>

Turn off current injected to heater by setting bit to

one

5.3.4.6 Heater profile selection- nb_conv

nb_conv set heater profile of the sensor.

Address

Content<bit position>

Description

ctrl_gas_1

0x71

nb_conv<3:0>

Forced mode: Indicates index of heater step that

will be used in forced mode as describe in below

table

Parallel mode: Indicates sequence of up to 10

heater steps

as describe in below table

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