Because the smartphone is the most used gadget, it can also be used in the car to play music on the car’s audio system or for hands-free calls.
How to connect your Android smartphone or iPhone to the car stereo unit?
There are several ways which we present below.
Connecting via the auxiliary connection
Most of the radio cd units have an audio jack connection available. This allows to connect the phone via an audio jack cable, and thus the radioCD becomes the amplifier by playing music from the phone. The connection is typically located on the front of the car audio unit, and in some cases is located in the back. The cable connects to the smartphone via the headphone jack, and then the playback can begin.
Connecting via Bluetooth.
Some of the best auto radioCDs have Bluetooth connection available, and for others connection can be obtained by purchasing a compatible Bluetooth module that connects to the unit. We activate the Bluetooth on the car audio unit, and then on the smartphone. The phone will start searching for nearby devices. From the displayed list we will choose to connect to the auto radiocd unit that usually carries her name. The devices will now be paired, and we can listen to music or have phone calls, the sound will be heard in the car speakers.
Connection via USB
Some newer car radio CD units allow you to connect the smartphone via cable USB to micro USB – the same cable used to connect the smartphone and the laptop. The USB port is usually on the front of the car audio unit. A special application must be installed on the smartphone from Google Play or Apple Store offered free by the audio unit manufacturer. Once connected by cable and the smartphone application being started, using controls on the audio unit we can search for the favorite songs in the audio library of the smartphone, and playback on the car speakers. It can search for folders, select some songs, and one of the advantages of this connection is that the smartphone is charging while connected, avoiding battery discharge.
Finally, on high end car audio units we have the NFC connection that we talked about here.
If the smartphone has this option, then we simply enable NFC on both audio unit and smartphone, allowing them to be connected – using the car’s audio system to play music from your phone, hands-free calls, or controlling the audio unit directly from your smartphone.
Another great article wich resumes everything is this one : https://techguylabs.com/blog/connect-smartphone-your-car-stereo