🔊 PCB Design Project (KiCad)

Bluetooth Speaker

A battery-powered Bluetooth speaker designed from scratch in KiCad — schematic, PCB layout, and full bill of materials for a BLE audio receiver built around an STM32WB wireless SoC, a software-driven R-2R DAC, and a dual-channel audio power amplifier.

Architecture

Antenna ── LFCN-2400 (2.4GHz filter) ── STM32WB15CCUx (BLE SoC)
                                              │
                                8-bit R-2R DAC (R1–R17, GPIO-driven)
                                              │
                                    TDA7297 (15W dual audio amp)
                                              │
                                    LS1 / LS2 (stereo speakers)

2× 3.7V Li-ion cells ── SW1 ── LM2596S-3.3 (buck reg.) ── 3.3V rail

• STM32WB15CCUx — ST's BLE 5.x wireless SoC handles the Bluetooth audio link and overall control. It has no onboard audio DAC, so the design drives 8 GPIO pins into an R-2R resistor-ladder DAC (R1–R17) to synthesize an analog audio signal directly in software.
• LFCN-2400 + antenna — 2.4 GHz low-pass filter and matching network on the RF front end.
• TDA7297 — 15 W dual bridge audio power amplifier driving two speakers in stereo.
• LM2596S-3.3 — switching buck regulator stepping the battery voltage down to a stable 3.3 V logic rail.
• 2× 3.7 V Li-ion cells — battery power, gated by a power switch with an LED status indicator.
• Tag-Connect (TC2030) SWD header — no soldered debug header needed; program/debug via a pogo-pin cable.

Full component list with reference designators is in hardware/BOM.md.

Schematic

PCB layout

Hardware

• hardware/bluetooth_spekare.kicad_pro — KiCad project file
• hardware/bluetooth_spekare.kicad_sch — schematic
• hardware/bluetooth_spekare.kicad_pcb — PCB layout
• hardware/BOM.md — bill of materials with supplier sourcing links

Open bluetooth_spekare.kicad_pro in KiCad (developed on KiCad 10) to view or edit the schematic and board.

Repository structure

.
├── hardware/
│   ├── bluetooth_spekare.kicad_pro
│   ├── bluetooth_spekare.kicad_sch
│   ├── bluetooth_spekare.kicad_pcb
│   ├── fp-lib-table
│   ├── sym-lib-table
│   └── BOM.md
├── docs/
│   └── images/          # 3D render, schematic, PCB layout
└── README.md

Author

Oskar Jabłonowski

License

MIT