DIY Bluetooth Receiver with aptX HD for Car Audio

If you're also interested in aptX HD and want to install a Bluetooth receiver in your car, why not check out this article and try a DIY project?

There's only one module or finished product that supports Bluetooth 5.0, aptX HD, has a microphone, and an earphone output: the BTI-031. There's another receiver specifically customized for the Levin/Corolla, which looks great, but unfortunately, it doesn't support aptX HD.

After testing, there's slight background noise. The lithium battery has some safety concerns under high temperatures, so it's recommended to remove the lithium battery and replace it with a 10µF/25V/0805 capacitor (located at the BAT section in the bottom left corner of the image). Upon checking, the power management chip U2 is the Chinese version of the LTC4054. This chip is used for charging lithium batteries, and if the output is only connected to a capacitor, it will repeatedly charge and stop. You can observe a 300mVpp periodic pulse on the power, which results in mild noise in the audio output. To resolve this, you can replace the chip with an XC6206P402MR, which eliminates the noise. Simply solder it back in the original position, remove a resistor, and short two adjacent pins without needing any flywires.

If you think it's unsightly to hang the receiver with audio and USB cables on the center console, you can create a socket. Just measure with a caliper, draw a design, 3D print it (using ABS material), spray paint it, and insert the USB and earphone plugs. Cut a hole in the bottom cover of the Bluetooth receiver, connect four wires to the socket and Bluetooth board for left channel, right channel, ground (since the USB and AUX in the center console don't share a ground, you'll need to connect the two grounds in the socket), and 5V. Then, use screws to secure the Bluetooth receiver's bottom cover and the printed socket (or you can use AB resin glue), attach the top cover, and you're done.