I have now make the I2C connections between the GridEye sensor and the Nano. The specific GridEye sensor that I purchased did not seem to have any accompanying documentation, although it was claimed there was some on the suppliers website but I could not find it. So, I decided that as it was a breakout board that most simple GridEye breakout boards would be pretty much the same so I used the Adafruit documentation and library.
There was one problem in that the GridEye is a 3.3V device but the PCB I have just says Vin. After a close look at the PCB there does seem to be a voltage regulator so assuming they would have put 3V instead of Vin if there wasn't a regulator I connected it to the 5V supply from the Nano. The other I2C connections were straight forward
SCL connects to A5 on the Nano
SDA connects to A4 on the Nano
Next I downloaded the Adafruit library and added it to my Arduino IDE (really easy and simple - once I had found the ZIP file on the Adafruit web page) and then loaded the AMG test programme provided in the examples (called amg88xx_test) which just checks that the I2C link is working properly by reading the GridEye internal thermistor. This was working correctly so I then downloaded the pixels-test programme from Examples which transfer the 8x8 array of temperature measurements, once every second. This also worked first time and it may be possible to see some of this data in the video below.
I will now have to start thinking about how to process the thermal array data so that I can (or might be able to) detect cats at night.