Classic Fitness-Tracking Digital Watch

I want to create a clean, classic-looking digital watch that quietly packs solid fitness features behind a minimal façade. The styling should stay timeless—thin case, simple dial, neutral colors, no flashy bezels—yet the internals must handle three core tasks:

• Continuous heart-rate monitoring
• Accurate step counting throughout the day
• Automatic sleep tracking each night

Your job is to design and prototype the complete device, covering electronics, firmware, enclosure and strap geometry. Low-power components, efficient firmware and a straightforward two-button or touchscreen-tap interface will keep the user experience elegant and the battery life sensible.

Please deliver:
• Schematics, PCB layout and full BOM
• Embedded code with clear build instructions
• 3D CAD files for the housing (print-ready)
• A working prototype or detailed assembly guide that proves every listed function operates correctly

Performance acceptance: heart-rate readings within ±5 bpm of a chest-strap reference, step accuracy ≥95 %, and sleep detection that distinguishes light, deep and awake states over an eight-hour test.

If you already work with common fitness-sensor modules, low-power ARM microcontrollers, BLE stacks or similar toolchains, that experience will come in handy. I’m happy to answer component or aesthetic questions quickly so you can move straight into design.