There was a time when we started our electronic projects with integrated circuits and other components, mounted on stripboard or maybe on a custom PCB. This is still the case for many devices, but it has become more and more common for a cheap off-the-shelf module to be treated as a part where it would once have been a project in its own right. We are happy to see the work of [ElectroBoy]who has combined something of both approaches by reverse engineering the pinout of a Chinese Bluetooth audio chip with a minimal datasheet, and creating his own take on a turnkey Bluetooth audio module.

The JL_AC6939B comes in a SOIC16 package and requires a minimum number of components. So the PCB is a relatively simple proposition and indeed it has all the parts and tracks mounted on one side with a copper base on the other. However, it is dangerous to assume that this is all a board like this needs, as many an engineer has gotten stuck designing a PCB antenna. We dare to surmise that the antenna here is just a wavy PCB line rather than an antenna of known impedance and bandwidth, at the very least it looks like it has much thicker traces than the one it’s copying.

It may not really be worth the effort to make a ready-made module that can be bought for relatively few cents, but to reject it is wrong. We make things because we can, not just because we have to.

This post Reverse engineer your own Bluetooth audio module

was original published at “https://hackaday.com/2022/03/26/reverse-engineering-your-own-bluetooth-audio-module/”