Infineon XENSIV PAS CO2 Shield2Go User manual

User Manual Please read the Important Notice and Warnings at the end of this document V 1.2
www.infineon.com page 1 of 23 2022-08-15
UM_2205_PL38_2206_121720
Quick-start guide for XENSIVTM PAS CO2
Shield2Go
About this document
Scope and purpose
This user manual serves as a starting guide and will focus on the setup and communication of the XENSIVTM PAS
CO2 Shield2Go. Mainfocus will be the hardware along with a quick example of how to set up communication and
start basic measurement with the provided software library using the XMC 2Go, the Arduino Due and the Arduino
Uno in combination with the my IoT adapter.
Intended audience
Application engineers, system engineers and makers.
Order information
Sales Name: SHIELD_PASCO2_SENSOR
SP-No: SP005569590
Opn: SHIELDPASCO2SENSORTOBO1
Table of contents
About this document....................................................................................................................... 1
Table of contents............................................................................................................................ 1
1Introduction .......................................................................................................................... 2
1.1 Shield2Go platform.................................................................................................................................3
1.2 XENSIVTM PAS CO2 Shield2Go..................................................................................................................4
2Software and library integration.............................................................................................. 8
2.1 Setting up Arduino IDE............................................................................................................................8
2.2 Library overview......................................................................................................................................8
3Quick start with XMC 2Go .......................................................................................................10
3.1 Step by step CO2 concentration readout example..............................................................................11
4Quick start with Arduino Due..................................................................................................18
5Quick start with Arduino Uno and My IoT adapter .....................................................................20
6Appendix..............................................................................................................................21
Revision history.............................................................................................................................22

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Quick-start guide for XENSIVTM PAS CO2 Shield2Go
Introduction
1Introduction
The XENSIVTM PAS CO2 sensor is a real carbon dioxide (CO2) sensor in an unprecedentedly small form factor.
Designed on the basis of a unique photoacoustic spectroscopy (PAS) concept, the sensor saves more than 75
percent space compared to existing commercial real CO2sensors. Its direct ppm readings, SMD capability and
simple design allow for quicker and easier integration into customers’ systems in low- and high-volume
applications alike.
The photoacoustic principle can be traced back to over 100 years ago, first discovered by Alexander Graham Bell
in 1880. The photoacoustic effect involves the formation of sound waves (pressure changes) following light
absorption in a material sample. The sound signal is quantified by detectors such as microphones. In order to
obtain this effect, the light intensity must vary. A PAS gas sensor is based on the principle that gases absorb light
in a specific wavelength of the infrared spectrum. CO2molecules, for example, have strong absorption in the λ=
4.2 µm wavelength.
The XENSIVTM PAS CO2 sensor module integrates, on the same PCB, the PAS transducer, a microcontroller for
signal processing, algorithms and a MOSFET. As depicted in the block diagram, the PAS transducer includes: i) a
proprietary infrared emitter with blackbody radiation, which is periodically chopped by the MOSFET; ii) a narrow-
band optical filter passing the CO2specific wavelength λ= 4.2 µm, significantly improving the sensor selectivity
compared to other gases, including humidity; and iii) Infineon’s high-SNR (signal-to-noise ratio) MEMS
microphone XENSIVTM IM69D130, detecting the pressure changes generated by the CO2molecules. All the
components are developed and designed in-house in accordance with Infineon’s high-quality guidelines. The
sensor therefore benefits from Infineon’s illustrious record of accomplishments in MEMS design and acoustic
capabilities, resulting in it being best-in-class for price/performance.
The XENSIVTM PAS CO2 sensor is ideal for smart-home and building automation as well as various indoor air
quality IoT devices such as air purifiers, thermostats, weather stations and personal assistants. The sensor
enables end users to track, understand and improve the air quality surrounding them in a timely and highly
energy-efficient manner.
Figure 1 XENSIVTM PAS CO2 sensor

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Quick-start guide for XENSIVTM PAS CO2 Shield2Go
Introduction
1.1 Shield2Go platform
Infineon’s Shield2Go boards are equipped with one featured Infineon IC and provide a standardized form factor
and pin layout for fast orientation. All boards come with solderless connectors allowing designers to stack the
boards instead of soldering them. This makes the Shield2Go boards simple, reusable and flexible. In addition,
each Shield2Go comes with a dedicated and free software library for Arduino. The Shield2Go boards are
compatible with Arduino Uno with Infineon’s My IoT adapter. This combination of flexible hardware components
and accompanying software speeds up the prototyping process. Engineers and makers can develop customized
system solutions by freely selecting and combining Shield2Go boards in multiple ways based on their needs and
use cases. Learn more about the Shield2Go approach and the available portfolio on the dedicated product page.
https://www.infineon.com/cms/en/tools/landing/infineon-for-makers/shield-2go-my-iot/
The My IoT adapter board is also part of the evaluation environment that acts as the gateway to external
hardware - such as the popular hardware platforms like Arduino, Raspberry Pi or Espressif Wi-Fi Chips -, making
it possible to combine the Shield2Go boards into systems easily and flexibly. The adapter offers multiple sockets
which allow free and flexible combination of various Shield2Go boards. Thereby, users do not have to care about
pin allocation, level shifting or system integration.
Figure 2 Combining Shield2Go board and My IoT adapter to a system
More and detailed information can be found on the dedicated My IoT product page.
https://www.infineon.com/cms/en/product/evaluation-boards/my-iot-adapter/

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Quick-start guide for XENSIVTM PAS CO2 Shield2Go
Introduction
1.2 XENSIVTM PAS CO2 Shield2Go
The XENSIVTM PAS CO2 Shield2Go includes every necessary component to fully supply the XENSIVTM PAS CO2 with
all the available features enabled and optimized. The necessary stable 12 V supply for the IR emitter is generated
on board with a boost converter and also additionally an LDO for the 3.3 V supply is integrated on board which
reduces the required supplies to a single 5 V supply. If user wants to use their own design it is possible to break
apart the head which only consists of the XENSIVTM PAS CO2 module with all the pins routed out on castellated
pads to easily mount the XENSIVTM PAS CO2 to the other PCBs. PWM and INT functionality is also covered in both
cases. Please refer to the programming guide and register map for full detailed description and examples.
https://www.infineon.com/dgdl/Infineon-programming_guide_PAS_CO2_evaluationkit-ApplicationNotes-
v02_00-EN.pdf?fileId=5546d4627600a6bc0176041139e77780
https://www.infineon.com/dgdl/Infineon-Registermap_description_PASCO2_MA2-ApplicationNotes-v02_00-
EN.pdf?fileId=5546d4627600a6bc017604238d967785
Figure 3 Block diagram of XENSIVTM PAS CO2 Shield2Go

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Quick-start guide for XENSIVTM PAS CO2 Shield2Go
Introduction
Two communication interfaces are available. By default, the I2C interface is configured but with a simple
rearrangement from the pull-up resistor R5 to pull-down resistor R6 can the UART interface be selected. To fully
disable the I2C interface and the connected pull-up resistors on the SDA/Tx and SCL lines solder jumpers can be
cut and disconnected. Figure 4 is showing the two positions the resistor can take depending on desired interface
and also above the solder jumpers for isolating the pull-up resistors R8 and R9.
Figure 4 Selecting communication interface on the XENSIVTM PAS CO2 Shield2Go

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Quick-start guide for XENSIVTM PAS CO2 Shield2Go
Introduction
Figure 5 Pinout XENSIVTM PAS CO2 Shield2Go
Table 1 Pin descriptions of body part
Pin
Symbol
Type
Function
1
VDD5
Power supply (5 V)
5 V step up to 12 V power supply for the IR emitter
2
NC
NC
Not connected
3
NC
NC
Not connected
4
P11: SDA
Input/Output
I2C data pin (3.3 V domain)
5
P10: SCL
Input/Output
I2C clock pin (3.3 V domain)
6
GND
Ground
Ground
7
VDD3V3
Power supply (3.3 V)
3.3 V digital power supply
8
P9: INT
Output
Interrupt output pin (3.3 V domain)
9
P8: PWM
Output
PWM output pin (3.3 V domain)
10
P7: TX
Input/Output
UART transmitter pin (3.3 V domain)
11
P6: RX
Input
UART receiver pin (3.3 V domain)
12
P5: RST
Input
Communication interface select input pin (3.3 V domain)1)
13
P4: GPIO1
Input
PWM disable input pin (3.3 V domain)2)
14
NC
NC
Not connected
15
NC
NC
Not connected
16
NC
NC
Not connected
17
NC
NC
Not connected

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Quick-start guide for XENSIVTM PAS CO2 Shield2Go
Introduction
Table 2 Pin descriptions of head part
1) High level selects UART and low level selects I2C. It is recommended to the user to hard wire the pin to VDD or
GND, depending on the wanted interface.
2) If a communication interface is used by the application, it is recommended to hard-wire pin PWM_DIS to GND.
Note: In this case the device will start in continuous mode and not idle mode which needs to be considered when
changing the measurement period.
Note: PSEL and PWM_DIS are both by default connected to GND on board of XENSIVTM PAS CO2 Shield2Go.
Pin
Symbol
Type
Function
1
VDD
Power supply (3.3 V)
3.3 V digital power supply
2
RX
Input
UART receiver pin (3.3 V domain)
3
SCL
Input/Output
I2C clock pin (3.3 V domain)
4
TX_SDA
Input/Output
UART transmitter pin/I2C data pin (3.3 V domain)
5
PWM_DIS
Input
PWM disable input pin (3.3 V domain)2)
6
GND
Ground
Ground
7
INT
Output
Interrupt output pin (3.3 V domain)
8
PSEL
Input
Communication interface select input pin (3.3 V domain)1)
9
PWM
Output
PWM output pin (3.3 V domain)
10
VDD12
Power supply (12 V)
12 V power supply for the IR emitter

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Quick-start guide for XENSIVTM PAS CO2 Shield2Go
Software and library integration
2Software and library integration
2.1 Setting up Arduino IDE
1. Install Arduino IDE. If you are new to Arduino, please download the program and install it first.
https://www.arduino.cc/en/software
2. Install the library. In the Arduino IDE, go to the menu Sketch > Include library > Manage libraries. Type
pas-co2-sensor and install the library.
Figure 6 Installing library in the Arduino library manager
3. In case of using XMC boards as microcontroller, install board package. The official Arduino boards are
already available in the Arduino software, but other third-party boards as the Infineon XMC MCU based
need to be explicitly included. Follow the instructions in section 3 “Quick start with XMC 2Go” to add the
XMC board family to Arduino.
2.2 Library overview
The core library is C based and provides a platform-independent driver for the XENSIV™ PAS CO2 sensor. It
provides full access to all features of the sensor. The driver consists of 4 files.
Table 3 Core C driver
Source code
Description
xensiv_pasco2_ver.h
Contains the exact version of the XENSIVTM PAS CO2 sensor
xensiv_pasco2_regs.h
Contains the register definitions for interacting with the XENSIVTM PAS CO2
sensor
xensiv_pasco2.h
Contains full functions for interacting with the XENSIVTM PAS CO2 sensor
xensiv_pasco2.c
Contains full functions for interacting with the XENSIVTM PAS CO2 sensor

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Quick-start guide for XENSIVTM PAS CO2 Shield2Go
Software and library integration
Full documentation and overview to the driver can be found on the GitHub.
https://github.com/Infineon/sensor-xensiv-pasco2
And the documentation with detail explanation for all macros, enumerations and functions can be found here:
https://infineon.github.io/sensor-xensiv-pasco2/html/group__group__board__libs.html
The Arduino library is using this core C driver with a C++ wrapper to follow the ecosystem design pattern so that
Arduino users find in this library what they are used to.
Table 4 Arduino library
The Arduino library includes 6 examples which the user can modify and use as a reference.
Table 5 Arduino examples
Full documentation of the Arduino library can be found on the GitHub.
https://github.com/Infineon/arduino-pas-co2-sensor
Source code
Description
pas-co2-pal-ino.cpp
Target platform-specific implementation
pas-co2-platf-ino.hpp
Default board definition and selection by conditional compiling
pas-co2-ino.hpp
Contains functions for interacting with the XENSIVTM PAS CO2 sensor adapted
from the core driver
pas-co2-ino.cpp
Contains functions for interacting with the XENSIVTM PAS CO2 sensor adapted
from the core driver
Example
Description
alarm-notification
Readout of the sensor CO2 concentration based on threshold crossing and
synched via hardware interrupt
device-id
Readout of the sensor devices product and revision identifiers
single-shot-mode
Readout of the sensor CO2 concentration value using single shot measurement
mode
continuous-mode
Readout of the sensor CO2 concentration value using continuous measurement
mode
forced-compensation
Set CO2 reference offset using forced compensation
early-notification
Readout of the sensor CO2 concentration based on early notification synched via
hardware interrupt

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Quick-start guide for XENSIVTM PAS CO2 Shield2Go
Quick start with XMC 2Go
3Quick start with XMC 2Go
The XMC 2Go is designed to evaluate the capabilities of the XMC1100 Microcontroller and the powerful, free of
charge tool chain DAVETM. Thanks to the standardized form factor of the XENSIVTM PAS CO2 Shield2Go it is directly
compatible with the XMC 2Go and can be used easily used in combination by plugging the XENSIVTM PAS CO2
Shield2Go on top of the XMC 2Go. But one important thing to consider is that the 5 V supply for the XENSIVTM PAS
CO2 Shield2Go is not provided by the XMC 2Go and therefore needs to be supplied externally.
Figure 7 XMC 2Go Kit board overview
Table 6 Features of the XMC 2Go Kit with XMC1100
Topic
Features
Processor
XMC1100 microcontroller (ARM® Cortex™-M0 based) in a 4 x 4 mm VQFN-24 package
Flash
64 kB
RAM
16 kB
Clock Generation
Internal Oscillator
Frequencies
32 MHz CPU clock, 64 MHz Timer clock
Dimensions
14.0 x 38.5 mm
Power Supply
from USB via Debug probe (J-Link) or 3.3V external power
Connectors
Two 8-pin header (pin pitch: 2.54 mm ≙0.1”/ between rows: 10.16 mm ≙0.4”)
Pin header fits to breadboard
Debugger
On-Board J-Link Debugger supports
•Serial Wire Debug (SWD, ARM Standard)
•Single Pin Debug (SPD)
•UART-to-USB bridge (virtual COM)

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Quick start with XMC 2Go
More and detailed information can be found on the dedicated XMC 2Go product page.
https://www.infineon.com/cms/de/product/evaluation-boards/kit_xmc_2go_xmc1100_v1/
3.1 Step by step CO2 concentration readout example
Figure 8 XENSIVTM PAS CO2 Shield2Go I2C interface connection to XMC 2Go
Table 7 Pin connections
Peripherals
Mapped to pin header X1/X2:
•2 Channel USIC (UART, SPI, I2C, I2S, LIN)
•6 Channel Analog to Digital Converter (12-Bit resolution)
•External Interrupts (via ERU)
•4 x 16-Bit Timer
Others:
•Real Time Clock
•Random Number Generator
Others
2 User LEDs @ P1.0 and P1.1
Position
Symbol
Connection to the XMC 2Go
1
VDD5
Not available on XMC 2Go, 5 V power supply needs to be
supplied externally
2
NC
Not connected
3
NC
Not connected
4
P11: SDA
I2C data pin (3.3 V domain)
5
P10: SCL
I2C clock pin (3.3 V domain)

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Quick-start guide for XENSIVTM PAS CO2 Shield2Go
Quick start with XMC 2Go
Figure 8 is just to visualize the connection because the XENSIVTM PAS CO2 Shield2Go can be simply stacked on
top of the XMC 2Go via pin headers as seen in figure 9.
Figure 9 XENSIVTM PAS CO2 Shield2Go I2C interface connection to XMC 2Go
In order to use and program the Infineon XMC microcontrollers in the Arduino IDE, SEGGER J-Link must be
installed first. Please follow the link to SEGGER J-Link and install the J-Link Software and Documentation Pack
for your operating system. If you have already installed 'DAVETM - Development Platform for XMCTM
Microcontrollers', you can skip this step as the respective drivers/programs are already installed on your system.
https://www.segger.com/downloads/jlink
6
GND
Ground
7
VDD3V3
3.3 V power supply
8
P9: INT
Digital pin D9
9
P8: PWM
Not connected (in this case)
10
P7: TX
Not connected (in this case)
11
P6: RX
Not connected (in this case)
12
P5: RST (PSEL)
Not connected (in this case)
13
P4: GPIO1 (PWM_DIS)
Not connected (in this case)
14
NC
Not connected
15
NC
Not connected
16
NC
Not connected
17
NC
Not connected

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Quick-start guide for XENSIVTM PAS CO2 Shield2Go
Quick start with XMC 2Go
Afterwards Infineon's microcontroller boards can be added to the Arduino IDE by pasting the following URL into
the 'Additional Boards Manager URLs' input field under File > Preferences.
https://github.com/Infineon/Assets/releases/download/current/package_infineon_index.json
Figure 10 Adding XMC boards to the Arduino IDE in the ‘Preference’ section
To install the boards, please navigate to Tools > Board > Boards Manager... and search for XMC. You will find
options to install the board files for the microcontrollers. Click "Install" to add the boards to your Arduino IDE.
Figure 11 Installing XMC microcontroller board files

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Quick-start guide for XENSIVTM PAS CO2 Shield2Go
Quick start with XMC 2Go
In the boards list Tools > Board, the XMC microcontroller boards are added and can be used from now on. After
that make sure to select the respective board (XMC1100 XMC2Go) and COM port in the Tools dropdown menu.
Figure 12 Selecting XMC 2Go board

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Quick-start guide for XENSIVTM PAS CO2 Shield2Go
Quick start with XMC 2Go
With everything ready, one of the library examples can now be opened, uploaded and run. The library examples
provided can be opened in File > Examples > pas-co2-sensor.
Figure 13 Arduino library examples

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Quick-start guide for XENSIVTM PAS CO2 Shield2Go
Quick start with XMC 2Go
In this case the serial-periodic example is used. The user can configure the I2C frequency, measurement period
and reference pressure. The sensor supports both standard-mode (100 kHz) and fast-mode (400 kHz). In case of
communication issues, it is recommended to lower the frequency to the standard-mode. For the measurement
period the default value is 10 s and it is recommended to not go lower than that. In this example the pressure is
set to 900 hPa. For correct operation, the user shall ensure that the pressure value programmed is within the
specified pressure operating range of the device. This valid range of operation is 750 hPa to 1150 hPa.
Figure 14 Arduino library example continuous-mode
Pressure must be set between 750 hPa and 1150 hPa

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Quick-start guide for XENSIVTM PAS CO2 Shield2Go
Quick start with XMC 2Go
Figure 15 Serial-periodic CO2 results output
Ensure J-Link is installed before compiling
Remember to connect the 5 V pin prior to starting sensor

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Quick start with Arduino Due
4Quick start with Arduino Due
Figure 16 XENSIVTM PAS CO2 Shield2Go I2C interface connection to Arduino Due3)
3) Pinout of Arduino Due from https://content.arduino.cc/assets/Pinout-Due_latest.pdf
Table 8 Pin connections
Position
Symbol
Connection to the Arduino Due
1
VDD5
5 V power supply
2
NC
Not connected
3
NC
Not connected
4
P11: SDA
I2C data pin (3.3 V domain)
5
P10: SCL
I2C clock pin (3.3 V domain)
6
GND
Ground
7
VDD3V3
3.3 V power supply
8
P9: INT
Digital pin D9
9
P8: PWM
Not connected (in this case)
10
P7: TX
Not connected (in this case)
11
P6: RX
Not connected (in this case)
12
P5: RST (PSEL)
Not connected (in this case)
13
P4: GPIO1 (PWM_DIS)
Not connected (in this case)
14
NC
Not connected
15
NC
Not connected
16
NC
Not connected
17
NC
Not connected

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Quick start with Arduino Due
Similar as with the XMC 2Go the Arduino Due board package needs to be installed first. As it is not a third-party
board like the XMC 2Go, the right package “Arduino SAM Boards” (32-bit ARM® Cortex-M3) which is including the
Arduino Due can be directly added with the board manager.
Figure 17 Arduino IDE settings: adding Arduino Due with the board manager
Afterwards the exact same steps with selecting the right board/COM port and opening, uploading and running a
library example can be done as instructed previously with the XMC 2Go.

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Quick start with Arduino Uno and My IoT adapter
5Quick start with Arduino Uno and My IoT adapter
As introduced in section 1.2 the XENSIVTM PAS CO2 Shield2Go in combination with the My IoT adapter can be
simply stacked on top of the Arduino Uno via pin headers. Pin allocation, level shifting and system integration is
already covered.
Figure 18 XENSIVTM PAS CO2 Shield2Go with My IoT adapter stacked to Arduino Uno4)
4) Pinout of Arduino Due from https://docs.arduino.cc/hardware/uno-rev3
Afterwards the exact same steps with selecting the right board/COM port and opening, uploading and running a
library example can be done as instructed previously with the XMC 2Go.
In case of any technical questions please visit our community forum and have a look if similar questions are
already posted or create a new one.
https://community.infineon.com/t5/CO-sensor/bd-p/CO2Sensors