How it works:

Logic:

• Uses an ESP32-WROOM-32 to handle Bluetooth audio transmission and audio adjustment using a potentiometer.

• I2S DAC IC works with esp32 to convert the digital music signals from the esp32 music into analog signals through the bone transducer 

• To flash code to the ESP32 we are using a CP2104 IC to convert our USB's Serial to UART. Some ESP32s have built in UART converters, the WROOM-32 does not.

Power:

• At the heart of the power system, have a charging IC from Nordic, it protects the battery, charges it via the USB-C port, and switches outputs between battery power or USB power depending on if its plugged in

• For our logic circuit, we use 3.3V so we use a 5v to 3.3v LDO to step down voltage.

• We're using a 1 cell Lithium Polymer 500mAh battery which has a built in battery protection circuit

• The battery is attached to the back of board in contact with a thermister for temperature monitoring.

Programming:

• The quick brown fox

Schematic:

Layout:

As recommended in the ESP32 docs, we placed the module in the corner of the board, with the antenna openning closest to the corner.

PCB 3D Model (only including important physical components):

Dimensions: 46.5mm x 47.7mm (including ESP32)

Bill of Materials: