Chest buckle guide - fochica/fochica-wiki GitHub Wiki

Many child seats come with a chest buckle, which is a secondary clip located at armpit level and is designed to position the seat belt in an optimal way. See this interesting blog and video about chest clips.

A sensor on a seat buckle that can sense if the buckle is closed or open is a good indicator of whether the seat is occupied or empty. Preferably this would be used in a multi-sensor setup to provide an additional data point. Typically you would attach a magnetic reed switch to the buckle which will provide the state to the Fochica device.

If your seat doesn't have a buckle that you can attach to easily, or if you don't want to mess with your existing buckle, it is possible to install a generic buckle and setup the sensor on it.

Search for "baby seat buckle". There are few sizes and form factors for you to choose from. Mind the length of the buckle and the distance between the belt slots.

It is recommended to add the reed sensor and wires to the buckle first and then to install the whole sensor on the chair.

If you want a set that is easy to put on and remove from the seat, then make 4 small cuts, one in each belt slot in the area where the two parts of the buckle touch each other. Then you could slide the part on to the seat belt from the outside in.