SMS messaging using GSM phones permits the passing of messages - normally between two humans but in this case - between a human and a small single chip computer.

The single chip computer is attached on one side to the cat flap and on the other to a mobile phone.

An enquiry message from a human is decoded by the computer and a reply is constructed that tells the human the Time, Date and direction of travel of the cat [in or out] for eight measurements.

IN	03:30	24
OUT	07:21	24
IN	09:47	24
OUT	15:23	24
IN	22:01	24
OUT	00:21	25
IN	05:53	25
OUT	07:30	25

 

 

On a mobile phone display it looks like this

The direction is followed by the time and the day date.