@Paul-Thornton Thanks for the pointers and @theshade thanks for the library. Can we find out how this works in deepsleep? Questions such as: Does the PCA remain powered up? Can we choose to power it down if we aren't using it? Can the PCA interrupt line be used? If so how? Can the PCA interrupt signal the PIC to wake the main processor from deepsleep? If so, how do we establish why we woke from deepsleep? Can the PIC tell us? Or perhaps you could just give us the schematics/PIC code and we could figure it out ;-) Thanks!!

@rskoniec On the gnd pin is a ground connected from a ldr, on the 3 volt pin is the ldr connected and the analog signal is converted to a digital signal to pin 3. The Pysense isn`t connected to the external board with the ldr when I was trying to upload the code. Now is there only ten headers soldered to the Pysense. I used a pair of female headers for the gnd and 3 volt pins and maile headers for the sensor pins