Audio Watermark Generator
About the Audio Watermark Generator PCB
Audio Watermark Generator is an open source STM32 PCB design by kristiangoystdal, published on GitHub. It is a 4-layer board measuring 83 × 41 mm, with 84 components from 51 distinct parts.
Its main chip is the STM32G431KBT6, from the STM32 family. Other key parts include the ISL91107IRTNZ-T7A, AMS1117-3.3, L9110S, MCP6072 and PAM8304. By type, the board carries 37 capacitors, 15 resistors, 9 ICs, 9 inductors, 7 connectors and 2 crystals.
It belongs with the audio and rf & radio designs in this gallery.
From the project
Real-time embedded audio watermark generator and decoder built for STM32 microcontrollers.
A low-cost, low-power system for embedding time-synchronized FSK metadata signals into audio recordings made by Autonomous Recording Units (ARUs). Designed for bioacoustic field deployments where cross-unit time synchronization and metadata recovery from audio alone are required.
The system encodes a structured metadata payload as a BFSK signal mixed into the audio recorded by any ARU model — either acoustically via a speaker, or electrically via a 3.5 mm cabled pass-through. A desktop demodulator extracts the metadata from recorded .wav files post-deployment.
Main components on the Audio Watermark Generator
Audio Watermark Generator bill of materials (BOM)
84 components, 51 distinct parts — part numbers from the project's BOM.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | STM32G431KBT6 | STM32G431KBT6 | IC1 |
| 1 | ISL91107IRTNZ-T7A | QFN50P300X400X80-21N | IC2 |
| 1 | AMS1117-3.3 | SOT-223-3_TabPin2 | U1 |
| 1 | L9110S | SOIC127P599X172-8N | U2 |
| 2 | MCP6072 | SOIC127P599X175-8N | U3, U4 |
| 1 | PAM8304 | PAM8304ASR | U5 |
| 1 | RTC_DS3231 | PinHeader_1x06_P2.54mm_DS3231 | U7 |
| 1 | CC1101 | CC1101 | U8 |
| 1 | 16MHZ 16MHz | Crystal_SMD_3225-4Pin_3.2x2.5mm | Y1 |
| 1 | NX3225GA-26MHZ-EXS00A-CG01972 | Crystal_SMD_3225-4Pin_3.2x2.5mm | Y2 |
| 1 | C2894326 USB_B_Micro | USB_Micro-B_Wuerth_629105150521 | J1 |
| 1 | Conn_01x03 | PinHeader_1x03_P2.54mm_Vertical_SMD_Pin1Right | J2 |
| 1 | Conn_01x04_Pin | PinHeader_1x04_P2.54mm_Vertical | J3 |
| 2 | SJ2-35954A-SMT SJ2-35954A-SMT-TR | CUI_SJ2-35954A-SMT-TR | J4, J5 |
| 1 | 533980271_PICOBLADE 533980271_Picoblade | MOLEX_533980271_Picoblade | J6 |
| 1 | CONSMA002-SMD-G-T | LINX_CONSMA002-SMD-G-T | J7 |
| 1 | 1049_18650_Battery | 1049_KEY_1 | B1 |
| 1 | AGQ210S03 | AGQ210S03 | K1 |
| 2 | C221841 SW_SPDT | SW_SPDT_PCM12 | SW1, SW2 |
| 1 | C2286 RED | LED_0603_1608Metric | D1 |
Show 31 more
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | 120R | L_0603_1608Metric | FB1 |
| 2 | 600R | L_0603_1608Metric | FB2, FB3 |
| 1 | 1KR 1kR | L_0402_1005Metric | FB4 |
| 1 | 1UH 1uH | L_1008_2520Metric | L1 |
| 3 | 27NH 27nH | L_0402_1005Metric | L121, L123, L131 |
| 1 | 22NH 22nH | L_0402_1005Metric | L122 |
| 1 | 4U7F 4u7F | C_0603_1608Metric | C1 |
| 5 | 100NF 100nF | C_0402_1005Metric | C2, C3, C9, C20, C51 |
| 3 | 10NF 10nF | C_0402_1005Metric | C4, C21, C22 |
| 3 | 1UF 1uF | C_0603_1608Metric | C5, C6, C15 |
| 2 | 10PF 10pF | C_0402_1005Metric | C7, C8 |
| 2 | 22UF 22uF | C_0805_2012Metric | C10, C11 |
| 2 | 10UF 10uF | C_0805_2012Metric | C12, C16 |
| 2 | 4N7F 4n7F | C_0603_1608Metric | C13, C14 |
| 7 | 220PF 220pF | C_0402_1005Metric | C17, C18, C23, C24, C25, C124, C125 |
| 1 | 1UF 1uF | C_0805_2012Metric | C19 |
| 3 | 22UF 22uF | C_0603_1608Metric | C26, C27, C28 |
| 1 | 12PF 12pF | C_0402_1005Metric | C81 |
| 1 | 15PF 15pF | C_0402_1005Metric | C101 |
| 2 | 3P9F 3p9F | C_0402_1005Metric | C121, C131 |
| 1 | 8P2F 8p2F | C_0402_1005Metric | C122 |
| 1 | 5P6F 5p6F | C_0402_1005Metric | C123 |
| 1 | 1K5R 1k5R | R_0402_1005Metric | R1 |
| 1 | 10KR 10kR | R_0402_1005Metric | R2 |
| 4 | 100KR 100kR | R_0805_2012Metric | R3, R4, R5, R6 |
| 1 | 2KR 2kR | R_0805_2012Metric | R7 |
| 2 | 10KR 10kR | R_0805_2012Metric | R8, R9 |
| 2 | 1KR 1kR | R_0805_2012Metric | R10, R12 |
| 1 | 1MR | R_0805_2012Metric | R11 |
| 2 | 330KR 330kR | R_0805_2012Metric | R13, R14 |
| 1 | 56KR 56kR | R_0402_1005Metric | R171 |
Audio Watermark Generator design files
The KiCad project lives in the kristiangoystdal/Audio_Watermark_Generator repository on GitHub; these links point at the commit this page was built from.
Audio Watermark Generator: common questions
What microcontroller does the Audio Watermark Generator use?
The Audio Watermark Generator is built around the STM32G431KBT6, from the STM32 family.
How big is the Audio Watermark Generator PCB?
The Audio Watermark Generator measures 83 × 41 mm, has 4 copper layers and is 1.6062 mm thick.
How many components are on the Audio Watermark Generator?
84 components, from 51 distinct parts, with part numbers taken from the project's own BOM. The full bill of materials is listed on this page.
Where can I download the Audio Watermark Generator design files?
From the kristiangoystdal/Audio_Watermark_Generator repository on GitHub, which has the KiCad layout, the schematic and the BOM; the links under Design files point to each one.
Can I use the Audio Watermark Generator design in my own project?
The repository has no license, so all rights stay with kristiangoystdal. Use it as a reference, and ask the author before reusing the design.
Can I test firmware for the Audio Watermark Generator without the hardware?
Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug STM32 firmware against it before you order a PCB.
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