The Bluetooth module wants 3.3v logic levels so that is taken into account. The image above shows a buffer chip doing the conversion, but the Fritzing schematic on the post uses a voltage divider.

Like a lot of mass-produced consumer goods, it turns out that the internal workings of Bluetooth headphones are the same across a lot of different brands. One common Bluetooth module is the CSR8645… ...

The GTI-ATM3330e Bluetooth 5.3 module from GlobalScale integrates Atmosic Technologies’ energy-harvesting technology for battery-free designs. GlobalScale, an original design manufacturer (ODM), ...

Bluetooth 3.0 + HS, as it'll be called, promises to be markedly faster than prior iterations thanks to the reliance on 802.11, which is the same protocol used by WiFi modules, routers, etc.

Renesas introduces the RX23W module with full Bluetooth Low Energy support for system and wireless communications control on IoT endpoint devices.

Equipped for Bluetooth 6 and 802.15.4, its embedded microcontroller is a 128MHz Arm Cortex-M33, backed by 1.5Mbyte of non-volatile Rram and 256kbyte of ram, and the module has a built-in antenna.

This isn’t the first Bluetooth low energy (BLE) module to hit the market but what makes this spectacular is that it happens to be the smallest ever made.