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CO₂ sensor Forum Discussions

_Mx_Px
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Hello everyone,

i have an issue with my XENSIV PAS CO2 for witch I have no ideas. I read data from sensor by Sensor2Go Kit and GUI downloaded from Infineon site, and the co2 value remains on 1000 - 1100 ppm. But when i connect sensor (without Sensor2Go Kit) to my microcontroller using I2C interface and try to read 0x05 and 0x06 registers the values i get are much higher (e.g. 0x05 gives 0x0c, 0x06 gives 0x1d). Those two concatenated gives 0x0c1d and that is 3101 in decimal.

What can be the reason that those two co2 values (1000 and 3101) are so different? Do I calculate it in a right way?

Thanks for Your help, this is my first time with that kind of problems.

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GeorgeT
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Moderator 25 solutions authored 10 likes received 50 replies posted
Moderator

Hi @_Mx_Px

Before going into the code please try the following changes:

1. Please use the capacitors in the voltage lines as in the datasheet (shown below) and repeat the measurement.

co2_sensor_applicaiton_circuit.png

2. If you are not having access to the capacitors try applying the voltages from the mini evaluation board voltage pins (12V and 3.3 V) to the sensor board while interfacing with the microcontroller.

XENSIV PAS CO2 motherboard miniboard.png

Let us know whether these changes helped in resolving the issue.

Thanks and regards,

George

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GeorgeT
Moderator
Moderator 25 solutions authored 10 likes received 50 replies posted
Moderator

Hi @_Mx_Px,

Yes, the calculation is correct.

As a first step please verify that the required levels of voltages (3.3 V and 12 V) are applied to sensor pins.

Please also refer to github pas-co2-sensor page for example codes for interfacing with microcontroller.

Thanks and regards,

George

_Mx_Px
Level 1
First like received First like given First reply posted
Level 1

Everything seems to be connected according to datasheet, stable 3.3V and 12V are on too, preassure in sensor is set. But the co2 value is still too high.

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GeorgeT
Moderator
Moderator 25 solutions authored 10 likes received 50 replies posted
Moderator

Hi @_Mx_Px,

Thanks for verifying that. Incorrect voltage levels can cause the sensor to show wrong readings. 

Please share the microcontroller details and the code being used at your end so that we can solve this issue. If you are using the code from github repository please let us know that.

Thanks and regards,

George

GeorgeT
Moderator
Moderator 25 solutions authored 10 likes received 50 replies posted
Moderator

Hi @_Mx_Px

Before going into the code please try the following changes:

1. Please use the capacitors in the voltage lines as in the datasheet (shown below) and repeat the measurement.

co2_sensor_applicaiton_circuit.png

2. If you are not having access to the capacitors try applying the voltages from the mini evaluation board voltage pins (12V and 3.3 V) to the sensor board while interfacing with the microcontroller.

XENSIV PAS CO2 motherboard miniboard.png

Let us know whether these changes helped in resolving the issue.

Thanks and regards,

George

_Mx_Px
Level 1
First like received First like given First reply posted
Level 1

It is working! It was a matter of unfiltered 12V supply. IR emitter seems to be very sensitive for it.

Thank You very much for Your help and time!
Michał