We recently purchased a treadmill and it has speakers built into the display but the only connection option is an 1/8″ jack on the right side of the console. Since we live in the 21st century I decided to add a Bluetooth receiver so I didn’t have to plug in a cable when I was walking.
After a few minutes on AliExpress I found a breakout board with the BK8000L chipset. It has a lot more functionality than I will use but the basic idea is that I’ll put an audio cable from it’s output to the treadmill audio input and when I get close enough to the treadmill the Bluetooth will attach and I’ll be off and running.
The board does have more features than I will use such as the ability to act as a speakerphone with the addition of a microphone, driving speakers directly, and forward/next track buttons.
If you want to experiment with Bluetooth audio, this is definitely a good choice!