• SHT31, BH1750, and SGP30 need environmental exposure.
• USB-C, the 5-pin base/JST cable, UART header, and camera FFC all need connector clearance and cable bend room.
• The ESP32-S3-WROOM antenna must stay at an exposed board edge with keepout.
• The enclosure face/camera/plugs may force the PCB to sit back from the exterior wall, which can make on-board environmental sensors ineffective unless they are deliberately exposed.

1. Single PCB with an exposed sensor edge, or
2. Main PCB plus a small sensor tongue/daughterboard.

Text
Top edge:
  ESP32-S3-WROOM antenna edge / RF keepout

Upper-middle:
  ESP32 body, boot/reset, local decoupling, short camera bus

Service edge, preferably one side or bottom:
  USB-C + 5-pin JST + UART/test access grouped together

Exposed environmental edge/tongue:
  SHT31 | SGP30 | BH1750, aligned to enclosure vent/window

Text
┌──────────────────────────────┐
│ ESP32 antenna edge            │
│ ESP32 module                  │
├───────────────┬──────────────┤
│ Power/USB     │ Camera FFC    │
│ support       │ short to ESP32│
├───────────────┴──────────────┤
│ USB-C | UART/test | JST       │  service connector edge
├──────────────────────────────┤
│ SHT31   SGP30   BH1750       │  exposed sensor edge/window
└──────────────────────────────┘

Text
Main PCB:
  ESP32, power, USB, JST, UART, camera FFC

Sensor tab/daughterboard:
  SHT31, SGP30, BH1750
  aligned to external vent/window/light aperture

• Put at an exposed edge or vent.
• Keep away from ESP32, regulators, USB power path, and SGP30 heat.
• Consider thermal isolation slots/cutouts around the sensor zone.
• Avoid large copper pours thermally connecting it to heat sources.

• Needs air exchange; avoid sealed cavities.
• Keep away from adhesives, silicone, conformal coating, and outgassing plastics.
• Avoid direct condensation/drip path.
• Do not place immediately adjacent to SHT31 if temperature accuracy is important.

• Needs optical exposure, not just airflow.
• Align to a light window/aperture/light pipe.
• Avoid shadows from cables, camera FFC, JST cable, enclosure ribs, or board overhangs.
• It may not belong in the same exact row as gas/humidity sensors unless the enclosure aperture supports both airflow and light.

• USB-C
• 5-pin JST base/soil connector
• UART/debug header or test pads

• ESP32 module handles RF internally.
• Most signals are I2C/UART/low-speed GPIO.
• USB is short.
• Camera bus is parallel but can be kept short if J4 is placed well.

• Bottom ground plane may get cut up by routing.
• Camera bus and USB return paths can become poor.
• More EMI/debug risk.
• Could require larger board area than 4-layer.
• More manual routing effort.

• Bottom layer remains mostly continuous GND.
• USB D+/D- are short and have a clean return path.
• Camera bus is short and grouped near ESP32/J4.
• Sensor row/tongue remains exposed and thermally isolated.
• Board does not grow significantly.

1. Which enclosure face contains the camera opening?
2. Which face should sense light?
3. Where will airflow vents be?
4. Do USB-C and JST need user access, or only assembly/service access?
5. Does UART need a connector, or can it become test pads?
6. Which direction should the camera FFC exit/bend?
7. Can the board have a small sensor tongue/protrusion?
8. Can sensors be on a daughterboard connected by a short cable/FFC?

1. Lock ESP32 antenna edge.
2. Lock camera FFC relative to camera/cable direction.
3. Group USB/JST/UART on service edge.
4. Create exposed sensor edge/tongue and place sensors there.
5. Place power/regulators away from SHT31/SGP30.
6. Place passives.
7. Route camera and USB first, then power, then low-speed nets.

• ESP32 antenna on top edge.
• Camera FFC on the edge closest to the camera module.
• USB/JST/UART grouped on one service edge.
• Sensors in a clean exposed row or, better, on a small sensor tongue/daughterboard.
• Keep 4-layer for the next pass; evaluate 2-layer only after this floorplan is mechanically coherent.