I tried to play my Sansa MP3 player through the car usb connection and received the error message that there were no files, or in other words the system could not recognize the mp3 files. I did see an option in the setup for car audio, but that failed also. Can anyone offer any help. Thanks!
If your car stereo has stereo auxiliary input, the obvious way to achieve this is with a 3.5mm stereo TRS to 2 RCA cable, or a 3.5mm stero TRS to 3.5mm stereo TRS cable. You may couple this with Rockbox's
Car Adapter Mode(*) which starts and stops playback based on detection of a power source, and supplying power to the device via USB from either a car cigarette lighter USB adapter or by using a "charge only" USB cable (a USB cable with just PWR and GND lines, and no D+/D- lines - these are cheap and readily accessible when searched for) and powering the player via the car head unit USB socket that apparently exists.
The reason to use a "charge only" USB cable or the car cigarette lighter adapter as a power source is so that the device doesn't attempt to enumerate as a mass storage device when it is connected, which requires manual intervention (holding any key during USB insertion) to prevent. So if car adapter mode is used, it is best to use a power-only source, or ensuring that the device has no ability to enumerate as mass storage over USB.
If you wish to do so, and have a spare USB cable, you can easily make a "charge only" USB cable by stripping some of the cable sheath and severing the D+/D- lines yourself. But if you wish to do this it is best to do so with a USB type A male to USB type A female adapter and the original USB cable for the device.
(* - Sansa Clip Zip manual is used because a specific model was not stated, but Car Adapter Mode settings apply to all Sansa devices.)
[Saint]