The CO2 sensor vendor's Application Note ( CO2meter.com AN162 "

Connecting SenseAir’s LP8 CO2 Sensor to Arduino
via UART" has text Arduino code.  Upon copying the code into the Arduino IDE, I discovered that parens and curly braces did not match up, and there is a serious issue with line endings. 

Compiling produced lots of errors. After spending several hours attempting to edit and compile, I contacted the folks at CO2meter.com, and a very helpful tech sent me a couple of files of Arduino code.  The code compiled, but I wasn't able to get a response from the sensor. 

Hooked up the o'scope, and discovered I had made an old and familiar mistake: had accidentally transposed TX and RX.  

OK, sensor working.  Whew. 

Next steps: 

port the code over to the Adafruit Adalogger M0. 

Get the RTC working. 

Log data to the Adalogger SD memory card.