you can do the 2 following techniques -
OEM SOS function and OEM TPMS
and connect to the reverse signal from the vehicle
NOTE: This type of head unit looks like this in the rear
Mazda 5 2 CR (2005-2010) sensors you can do the 2SPECIFICATIONS Brand Name: T'EYES Certification: CE,EAC Digital Media Format: Mp3,MP4,WMA,JPEG Din: One Din Display Size: 9" For Vehicle Brands Model: MAZDA Hign concerned Chemical: None Item Weight: 2 OSD Language: Chinese (Simplified),Chinese (Traditional),Russian,English Operating System: Android Special Features: wifi function,Support steering wheel control,Support Can Bus,Built in GPS,Mobile Phone,MP3 players Voltage: 12 V