CO₂ sensor Forum Discussions

Hi, I am trying to interface an external MCU with EVAL_PASCO2_MINIBOARD using i2c at bus speed of 100 kHz. I tried reading several registers 0x00, 0x01, 0x0F, etc. But with all read attempts I am only getting the return data value 74 (0x4A).  Irrespective of the register address the return data is always 74, when the board is powered-up. I don't have any issue in communicating with other i2c peripherals on the same board. Any idea what this might be happening? 

I am programming in LUA on a NODEMCU board interface to MINIBOARD, with the following code:

co2_address = 0x28

i2c.setup(self.id, sda, scl, i2c.SLOW);  \\SLOW=100kHz

----------------------------------------------------------------------

//Read Function

read_reg = function(self, reg_addr)
i2c.start(self.id)
i2c.address(self.id, co2_address, i2c.TRANSMITTER)
i2c.write(self.id, reg_addr)
i2c.stop(self.id)
i2c.start(self.id)
i2c.address(self.id, co2_address, i2c.RECEIVER)
c=i2c.read(self.id,1)
i2c.stop(self.id)
return c
end

------------------------------------------------------------------------

reg = co2_sensor:read_reg(0, 0x01)
print(string.byte(reg))

-------------------------------------

Console Print = 74

Thanks for any advise.

I noticed that there are inquiries about usage of the Sensor2Go CO2 sensor kit with linux as per the post by  @weixiaohalou : https://community.infineon.com/t5/CO-sensor/Infineon-XENSIV-CO2-sensor-data-transmission/td-p/326268

Is there any sample code to enable that? I'm also just looking to be able to download data using python from a standard MCU like a Raspberry Pi. I'm noticing a bunch of code on github for enabling this board with various other arduino or other MCU boards, but using the USB interface seems to b

Regarding Infineon-XENSIV_CO2_sensor, when it is connected to a computer with USB, does the sensor only work when the software XENSIV PAS CO2 Sensor2Go GUI is opened? Now I want to transfer the measured CO2 data to the Raspberry Pi via USB. Instead of computer software, what instructions need to be executed on the sensor, is it serial port operation on CY7C65213-32L TXI or is there any other method?

Dear CO2 team,

During the testing of the CO2 sensor I noticed an increased noise figure of the sensor.

Below approximately 620 ppm the noise figure increases. I have no idea why.

All sensors are placed in an temperature controlled chamber.

In the picture you can see 4 lines:

Red = PASCO2 sensor A, interfaced via I2C with our own electronics (interval 5 [s])

Blue = PASCO2 sensor B, interfaced via USB with the evaluation board (interval 10 [s] ?)

Green = SCD41 sensor (Sensirion), interfaced via I2C (interval 5 [s])

Cyan = 415 [ppm] (outside air)

In the bottom graph you can see the difference between successive measurements which we use as a noise figure.

Why is this sensor displaying this behaviour? and how can I resolve this issue?

Kind regards,

Martin

Actual Measurement Result
When CO2 was injected into the closed space with the PAS CO2 Sensor, the CO2 concentration in the GUI increased immediately.
16:10:49(JST)/500ppm ⇒ 16:10:59(JST)/1500ppm
After that, it stabilizes at 32618ppm.
Leave PAS CO2 from enclosed space to open space (≈400ppm) at 16:16:39(JST)
16:21:49(JST)/32765ppm
16:21:59(JST)/32671ppm
16:22:09(JST)/18915ppm
16:22:19(JST)/7576ppmm

16:31:39(JST)/436ppm, Finally back to the CO2 concentration of the open space. Why does it take so long, 15 minutes, to get back to normal?

Translated with www.DeepL.com/Translator (free version)

I am using PAS CO2 sensor in single shot mode. Power up sequence: +3.3V , then +12V, then wait minimum 1s.

PWM_DIS connected to 3.3V, PSEL connected to GND. 

I trigger a measurement every minute, enabling ABOC in the field BOC_CFG (register MEAS_CFG). [write 0x05 into MEAS_CFG]

Then I wait minimum 2 seconds, and afterwards I read out the measurement value. Outdoor (country side, clean air) I get values around 800ppm. Whether I enable or not the ABOC, the measured values seem to be the same. 

Am I missing something? 

In the end I assumed there is a sensor offset of ~400ppm, and I subtracted it from the measured values. Is this a valid approach?