Desktop speaker is transformed into a Bluetooth speaker. Since the speaker at home only supports wired connection, I want to change it into a Bluetooth + wired two-in-one speaker, so I made such an audio switching thing. Which M18 is the one I bought for 6 yuan? Bluetooth module

0x00. I have a wired speaker at home, and I suddenly want to change it to a Bluetooth + wired "dual-mode" speaker.

0x01. I’ve been searching for a long time on a certain website but haven’t found a ready-made board that can switch between wired input and Bluetooth. So I drew one myself.

0x02. Because I want to use homeassistant to switch external input audio and Bluetooth audio, I searched for a long time and found a chip called CH440 that can achieve this.

0x03.CH440 can do 8 inputs and 4 outputs, which seems a bit excessive for use here. However, it is cheaper. It doesn’t matter anymore.

0x04. Since this Bluetooth module supports operations such as switching songs, I made several buttons and connected 8266 for control. It lived up to expectations and occupied several 8266 IO ports.

0x05. They all have silk screen marks, so you should be able to understand them.