Hybrid Smartwatch Design Inquiry
Worked for 37 sec
Enlarged the PCB from 40 mm circular to 42 mm circular on a 4-layer stackup. This keeps it within the 44 mm case target while improving density from critical to high.
Open items:
- Routing is still tight, especially around the ESP32/RTC/regulator area.
- A few passives may still need to move to the bottom layer for clean routing.
Suggested next steps:
- Spread the crowded ESP32/RTC/power components.
- Move low-profile passives to the bottom side.
- Run routing feasibility again before autorouting.
the esp doesnt fit
Thought for 4 sec
I’ll inspect the ESP32 module placement and board clearance, then move/orient it so the module body and antenna keepout fit within the enlarged round PCB/case constraints.
Worked for 51 sec
Fixed the ESP32 fit issue: U1 was protruding past the 42 mm circular board, so I moved it inward. It is now fully inside the PCB outline at approximately (0, 5 mm).
Open items:
- Moving U1 inward created new routing congestion between U1, U5, J1, and J3.
- The next placement pass should spread the motor driver/AMOLED connector area and possibly move small passives to the bottom side.
Suggested next steps:
- Re-place the crowded U1/U5/J1/J3 cluster.
- Move selected passives to the bottom layer.
- Run routing feasibility again.
Re-place and check
Re-place crowded cluster
Move passives bottom
Run layout review
Protect antenna keepout
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Center-Hole Round AMOLED/OLED Display Research
Goal
Find a round AMOLED/OLED display option that makes physical analogue hands practical by allowing a center shaft or center aperture through the display stack.
Short answer
I did not find a clearly purchasable, off-the-shelf 1.32 inch QSPI AMOLED with a mechanical center hole. Standard round AMOLED watch modules are generally solid panels. However, I did find several credible custom/semi-custom AMOLED supplier paths that explicitly mention round AMOLED cutouts or drilled-hole customization.
For this smartwatch, the practical path is either:
- Custom center-hole AMOLED / annular AMOLED module — best visual match, highest sourcing risk/cost.
- Center-hole TFT LCD module — proven in hybrid watches, easier mechanically, worse black level/contrast than AMOLED.
- No-hole AMOLED with hands above a central decorative hub/bridge — avoids piercing display, but requires more complex mechanical support and may reduce realism.
Best supplier leads
1. ATE Store — Truly Circular AMOLED Display
- URL: https://www.atestore.de/en/truly-circular-amoled-display.html
- Relevance: strongest direct AMOLED lead.
- Finding: page states optional central or side cutout / hole support and lists “Optional: With hole (cutout)”.
- Limitations: page does not expose exact sizes, interface, FPC pinout, MOQ, or whether the cutout can be used for a rotating watch hand shaft rather than only sensors/cameras.
- Action: contact supplier for 1.32–1.43 inch round AMOLED, 466×466, QSPI/SPI/MIPI, central 5–6 mm aperture, on-cell touch optional, FPC orientation, module thickness, and MOQ.
2. US Micro Products — Custom AMOLED Displays
- URL: https://www.usmicroproducts.com/displays/custom-amoled-displays
- Relevance: custom AMOLED engineering provider.
- Finding: supports custom AMOLED panel shape: round, size range 0.39–6 inch, and cover options including drill hole.
- Limitations: “drill hole” may refer to cover glass rather than active OLED panel aperture; must verify actual active-panel cutout capability.
- Action: ask specifically whether the active AMOLED panel can have a center through-hole, not just the cover lens.
3. DisplayModule — Round AMOLED customization
- URL: https://www.displaymodule.com/de/blogs/knowledge/round-amoled-display-supplier-smart-watch-touch-panel-custom-cover-glass
- Relevance: round AMOLED module and smartwatch integration supplier.
- Finding: discusses custom cover glass, hole position, window shape, FPC direction, module thickness, waterproof gasket integration, and smartwatch housing alignment.
- Limitations: content appears focused on cover glass/sensor openings rather than guaranteed active AMOLED center hole.
- Action: contact for custom round AMOLED module with active center aperture or an inactive center island suitable for a shaft tube.
4. MyKronoz ZeTime / ZeTime 2 and LG Watch W7 precedent
- Relevance: confirms the hybrid display + mechanical hands concept is mechanically real.
- Finding: ZeTime used mechanical hands through a center hole in a round color display; LG Watch W7 used a circular LCD with a center hole and a Swiss movement.
- Limitation: these examples were mainly TFT LCD, not clearly off-the-shelf AMOLED modules.
5. Center-hole TFT LCD lead — ORC0122-01 / 1.22 inch ST7789H2
- Relevance: likely easier fallback if true center-hole AMOLED cannot be sourced.
- Finding: search results mention 1.22 inch round TFT LCD with center hole, 240×240, ST7789H2, SPI.
- Limitation: lower resolution/contrast and less premium look than 1.32 inch 466×466 AMOLED.
Fit against 44 mm watch concept
A center-hole display should target:
- Active diameter: 32–35 mm preferred, leaving bezel/ring space inside a 44 mm case.
- Center aperture: initial 5–6 mm diameter for coaxial hour/minute shaft and decorative cap.
- Interface: QSPI or SPI preferred for ESP32-S3; MIPI possible only with a bridge or different controller strategy.
- Module thickness: ideally ≤1.5 mm.
- FPC exit: must avoid the motor/gear module and allow a safe bend radius.
- Touch: optional; on-cell touch adds stack complexity and may conflict with the shaft aperture.
Engineering conclusion
The current 1.32 inch QSPI AMOLED remains the best electrical/display choice, but it is not yet mechanically proven for physical hands because no off-the-shelf center-hole variant was confirmed. The most realistic next design decision is to switch the display requirement from “known 1.32 QSPI AMOLED module” to “custom/semi-custom 1.32–1.43 inch center-hole AMOLED target,” while keeping the current schematic connector provisional.
If suppliers cannot confirm an active-panel center hole, the fallback should be a center-hole TFT LCD or a no-hole AMOLED with a separate above-display hand bridge.
Supplier inquiry checklist
Ask each supplier:
- Can the active AMOLED panel itself include a center through-hole, not just the cover glass?
- What minimum center-hole diameter is allowed?
- Is a 5–6 mm center hole possible on a 1.32–1.43 inch round AMOLED?
- What dead-zone / seal / inactive border is required around the hole?
- What interface options are available: QSPI, SPI, MIPI DSI?
- Can the module provide 466×466 or similar resolution?
- What is the total module thickness including touch/cover glass?
- What FPC orientation and connector pitch are available?
- What MOQ/NRE and lead time apply for a custom center-hole module?
- Is the center hole suitable for a rotating mechanical shaft/tube, including wear, debris, and assembly tolerances?
Goal
Short answer
Best supplier leads
1. ATE Store — Truly Circular AMOLED Display
2. US Micro Products — Custom AMOLED Displays
3. DisplayModule — Round AMOLED customization
4. MyKronoz ZeTime / ZeTime 2 and LG Watch W7 precedent
5. Center-hole TFT LCD lead — ORC0122-01 / 1.22 inch ST7789H2
Fit against 44 mm watch concept
Engineering conclusion
Supplier inquiry checklist
