CozIR
®
-LP3 Evaluation Board User Guide
Revision 1.5: 15 December 2020
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diffused into the sensor. If there is no value in the ‘Set to’ dialogue box, when ‘Ambient’ is clicked,
the sensor will be zeroed assuming the ambient environment is 400ppm.
The CO
2
concentration fresh air zero level is programmable over a range from 0ppm to the full scale
of the sensor. The software default is 400ppm as the fresh air CO
2
concentration value. However,
the user can write a different fresh air value to the sensor if desired.
To write a different fresh air CO
2
concentration value to the sensor, set the CO
2
concentration value
to the appropriate value by writing the value in the ‘set to’ box. Click on ‘Ambient.
ZERO IN A KNOWN GAS CONCENTRATION
Place the sensor in a known gas concentration, and allow time for the sensor temperature to
stabilise, and for the gas to be fully diffused into the sensor. Set the CO
2
concentration value to the
appropriate value by writing the value in the ‘set to’ box. Click on ‘Known Gas’.
AUTO-ZERO FUNCTION
The sensor has a built-in auto-zeroing function. To function correctly, the sensor must be exposed to
typical background fresh air levels (~400ppm) at least once during the auto-zero period. The auto-
zero function uses the information gathered during these periods to re-zero. The sensor will reset
the ‘zero’ level every time it does an auto-zero. Auto-zeroing is enabled by default. If the sensor is
powered down, the auto-zero is reset to default fresh air value, 400ppm. The user can change this
default value.
The auto-zero function works in the same way as the ‘Ambient’
command.
AUTO-ZERO INTERVALS
The auto-zero period can be programmed by the user. The sensor can be programmed to undertake
an initial auto-zero after power-on. Thereafter, the auto-zero period can be set independently of
the start-up auto-zero time. Note, the auto-zero settings are reset if the sensor is powered down.
Write the ‘Initial interval’ and ‘Normal Interval’ period in the box and click on ‘Auto Zero’.
