Temperature and Humidity Sensor Node Design

flux

Current state: the project is still empty, so nothing has been added yet — no schematic, components, nets, or layout.
What I would build next for your node:
  • Core: a low-power dual-radio MCU with 2.4 GHz Wi‑Fi + BLE 5.x, most likely an ESP32-C6 or ESP32-S3 class device depending the exact sleep/current and firmware tradeoff you want.
  • Sensor: a digital temperature/RH sensor such as SHT4x or HDC302x, connected over I2C.
  • Power input: USB-C receptacle configured as 5 V sink default with CC pulldowns.
  • Protection/power path: input fuse or eFuse, reverse-current/reverse-polarity protection, OVP/UVLO/OCP-capable front end sized for 0.5–3 A source compatibility, then a regulated 3.3 V rail for the MCU and sensor.
  • Consumer-use details: ESD protection on USB-C, proper decoupling throughout, RF keepout/antenna considerations, and a clean schematic that can pass review before layout.
What remains to be done:
  1. Choose the exact MCU/module and sensor from datasheets.
  2. Calculate the full power budget and size the USB-C protection and regulator path correctly.
  3. Create the schematic with all support parts, decoupling, bootstraps, pull-ups, and protection.
  4. Verify the design against datasheets and review checks.
  5. Then move to PCB layout, placement, and routing after your confirmation.
One important design decision still open:
  • If you want the fastest, lowest-risk path, I’d use a certified RF module rather than a bare MCU + RF matching network.
  • If you want the lowest BOM cost and smallest board, a bare chip solution is possible but more RF-sensitive.
Recommended starting architecture:
  • USB-C 5 V sink
  • USB ESD + protected power-path IC/eFuse
  • 3.3 V regulator
  • ESP32-class Wi‑Fi/BLE device
  • I2C temperature/humidity sensor
  • Optional status LED and programming/debug header
If you want, I can next turn this into a concrete part-by-part schematic plan with recommended components and rail/current targets.
Certified module plan
SHT41 power sizing
Compare MCU modules
USB-C protection
Save requirements
U1
Manufacturer Part Number
HTU21D
  • Generic Inductor
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    A generic fixed inductor suitable for rapid circuit topology development. The footprint automatically adapts based on the selected package, supporting standard SMD sizes (e.g., 0402, 0603, 0805) as well as well-known inductor packages such as SDR1806, PA4320, SRN6028, and SRR1260. Standard inductor values: 1.0 nH, 10 nH, 100 nH, 1.0 µH, 10 µH, 100 µH, 1.0 mH 1.2 nH, 12 nH, 120 nH, 1.2 µH, 12 µH, 120 µH, 1.2 mH 1.5 nH, 15 nH, 150 nH, 1.5 µH, 15 µH, 150 µH, 1.5 mH 1.8 nH, 18 nH, 180 nH, 1.8 µH, 18 µH, 180 µH, 1.8 mH 2.2 nH, 22 nH, 220 nH, 2.2 µH, 22 µH, 220 µH, 2.2 mH 2.7 nH, 27 nH, 270 nH, 2.7 µH, 27 µH, 270 µH, 2.7 mH 3.3 nH, 33 nH, 330 nH, 3.3 µH, 33 µH, 330 µH, 3.3 mH 3.9 nH, 39 nH, 390 nH, 3.9 µH, 39 µH, 390 µH, 3.9 mH 4.7 nH, 47 nH, 470 nH, 4.7 µH, 47 µH, 470 µH, 4.7 mH 5.6 nH, 56 nH, 560 nH, 5.6 µH, 56 µH, 560 µH, 5.6 mH 6.8 nH, 68 nH, 680 nH, 6.8 µH, 68 µH, 680 µH, 6.8 mH 8.2 nH, 82 nH, 820 nH, 8.2 µH, 82 µH, 820 µH, 8.2 mH #generics #CommonPartsLibrary
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  • Generic Resistor
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Raw Purple R2-D2

Raw Purple R2-D2 thumbnail
Welcome to your new project. Imagine what you can build here.

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