ESP32 Low-Power Audio Device — PCB Design + Firmware (KiCad, Digital Files)

Building a Catholic Prayer Chime Device — Electronics Design Phase

We're developing The Angelus Chime, a battery-powered devotional device that plays authentic church bell recordings at 6 AM, 12 PM, and 6 PM. This is Phase 1 of a two-phase development strategy focusing exclusively on electronics design.

IMPORTANT: This engagement delivers DIGITAL FILES ONLY
- No physical prototypes
- No assembly required
- No enclosure work (handled in separate Phase 2)
- Pure electronics design and firmware development

DEVICE OVERVIEW
A sacred object for the home — a device that sits on your mantel and rings real church bells three times a day, just as they have for 700 years across Europe. No app, no WiFi, no Bluetooth. Just bells.

CORE FUNCTIONALITY
- Plays 2-3 minute authentic church bell recordings at prayer times
- 3 toggle switches to enable/disable each prayer hour independently
- Rotary switch to select from 8-12 bell recordings stored on onboard SPI flash
- Volume control via rotary knob
- Large mute button — stops playback immediately
- Time set once via small hidden display — no syncing, no updates
- Target: 1+ year battery life on 3-4 AA batteries using deep sleep architecture

TECHNICAL REQUIREMENTS

Microcontroller: ESP32 (preferred) or STM32 — WiFi/BT disabled for maximum battery life
Real-Time Clock: DS3231 with coin cell backup (±2 ppm accuracy)
Audio Output: I2S DAC/amp (MAX98357A or better) + premium full-range speaker connection. Audio quality is CRITICAL — must sound like real church bells, not a phone alarm.
Storage: Onboard SPI flash (W25Q128 — 16MB) for WAV/MP3 recordings. No microSD.
Controls: Rotary switches (bell selection + volume), toggle switches (3x prayer hours), push buttons (time setting), mute button
Display: 4-digit 7-segment or 0.96" OLED (time setting only, hidden in base)
Power: 3-4 AA batteries, deep sleep architecture, 1+ year target battery life

CRITICAL: JLCPCB OPTIMIZATION
- Must use components from JLCPCB's parts library: https://jlcpcb.com/parts
- Prefer "Basic" parts over "Extended" to minimize assembly fees
- Non-negotiable — directly affects manufacturing cost

MODEL-AGNOSTIC DESIGN
The PCB and firmware must work across three product models with minimal changes:
1. The Vesper — Compact desk/bedside (4-5")
2. The Sanctus — Mantel display (6-8") — PRIMARY TARGET
3. The Cathedral — Grand room display (USB-C powered)
Same PCB, same firmware. Design for scalability.

DELIVERABLES (DIGITAL FILES ONLY)
1. Complete schematic files (KiCad preferred)
2. PCB layout files
3. JLCPCB manufacturing files: Gerbers, NC Drill, Pick-and-place
4. Bill of Materials with verified JLCPCB part numbers
5. Firmware source code (Arduino or ESP-IDF) — clean, commented, production-ready
6. Documentation (setup guide, user instructions)
7. Cost estimate for 100-unit production run via JLCPCB
8. Scalability notes for all three models

BUDGET & TIMELINE
Budget: $800-$1,200 USD (fixed price, milestone-based)
Timeline: 2-4 weeks

TO APPLY — MUST INCLUDE:
- A relevant ESP32 custom PCB project you've completed
- Your approach to deep sleep + RTC wake + I2S audio architecture
- Confirmation you can design for JLCPCB's parts library
- A rough cost/timeline breakdown by milestone
- Include 'ANGELUS-ESP32' in your proposal
- Any questions about the spec

This is Phase 1 of a two-phase strategy. Phase 2 (gothic cathedral enclosure design) will be handled by a separate 3D industrial designer. Fabrication via JLCPCB/PCBWay.