The button states could easily be read by using an Arduino’s analog input. A Pro Mini model was chosen for its small size as it could be housed in the radio compartment of the dash.

Offered in a 6-pin SON package, the controllers are priced at US$0.40 in 1,000-unit quantities. For those applications requiring a single push-button input, TI offers the TPS3422 priced at US$0.34.