Wi-Fi/Bluetooth Sensor Node Design
Worked for 4 mins 51 sec
Architecture and power budget are captured in the project specification. I’m adding the schematic parts now: USB-C, eFuse protection, 3.3 V buck, ESP32-C3 module, SHT41 sensor, USB ESD, and support passives.
Worked for 7 mins 30 sec
Implemented the USB-C Wi‑Fi/BLE temperature-humidity sensor node schematic.
What’s done:
- Added and wired USB-C 5 V sink input, CC pulldowns, USB data ESD protection, TPS25210 eFuse protection, AP63203 3.3 V buck, ESP32-C3-WROOM-02, SHT41 I2C T/RH sensor, boot/reset buttons, decoupling, pull-ups, and status LED.
- Created the detailed Project Specification with architecture, datasheet notes, and power budget.
- Created Firmware Starter with PlatformIO setup and compilable ESP32-C3 Arduino code.
Validation note: schematic/ERC checks did not report unresolved electrical issues in the targeted ERC pass. The remaining review errors are expected pre-layout items: unrouted airwires, overlapping unplaced footprints, and generic passive MPNs before manufacturing BOM finalization.
Next checkpoint: the schematic is ready to move into PCB layout and placement. Want me to go ahead?
Set board layout
Run ERC/DRC
Finalize passives
Auto-place components
Add mounting features
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Project Specification — USB-C WiFi BLE T-RH Sensor Node
Requirements
- Consumer low-power environmental node.
- USB-C receptacle, 5 V default sink input.
- Plan for USB-C sources advertising 0.5 A to 3 A; the design must not assume 3 A is always available in firmware/use.
- Digital temperature / relative humidity sensor.
- Ultra-low-power Wi-Fi + Bluetooth dual-radio MCU: 2.4 GHz 802.11 b/g/n and BLE 5.x.
- Input path must include reverse-current/reverse-polarity, overvoltage, undervoltage lockout, and overcurrent protection.
Selected architecture
- USB-C USB 2.0 receptacle: GCT USB4105-GF-A.
- USB-C sink detection: independent 5.1 kΩ Rd pulldowns on CC1 and CC2.
- USB data: routed to ESP32-C3 native USB Serial/JTAG through USBLC6-2SC6 ESD protection.
- Input protection: TPS25210LRPWR eFuse, 2.7 V to 5.7 V operating input, 4 A switch, reverse current blocking, input reverse-polarity protection, overvoltage clamp, adjustable UVLO and current limit.
- 3.3 V conversion: AP63203WU-7 fixed 3.3 V synchronous buck regulator, 2 A output capability.
- MCU/radio: ESP32-C3-WROOM-02-N4 module, 3.0 V to 3.6 V supply, Wi-Fi 802.11 b/g/n and Bluetooth 5.
- Sensor: Sensirion SHT41-AD1B-R2 I2C T/RH sensor, VDD 1.08 V to 3.6 V, address 0x44.
Datasheet-grounded design notes
- ESP32-C3 requires stable 3.3 V rail capable of at least 0.5 A. Peak Wi-Fi TX current from datasheet is 345 mA at 802.11b 1 Mbps, 20.5 dBm.
- ESP32-C3 EN must not float. Use 10 kΩ pull-up and 1 µF RC delay/filter per Espressif peripheral schematic guidance.
- ESP32-C3 boot/download: GPIO9 weak-pull-up default = SPI boot; pull GPIO9 low with BOOT button for joint download boot. GPIO2 is recommended pulled up.
- ESP32-C3 USB Serial/JTAG uses GPIO18 = USB_D- and GPIO19 = USB_D+.
- SHT4x typical application: SDA/SCL pull-ups to VDD, 100 nF capacitor from VDD to VSS close to sensor.
- AP63203 fixed 3.3 V typical application: 10 µF input capacitor, 3.9 µH inductor, 2 × 22 µF output capacitors, 100 nF bootstrap capacitor.
- TPS25210L USB 5 V protection design example: UVLO 4 V using 470 kΩ / 205 kΩ divider, OVCSEL open for 5.7 V clamp, RILM 953 Ω for 3.5 A current limit, 1 nF dVdt capacitor, 2.2 nF ITIMER capacitor, 10 µF output capacitor.
Power budget
Table
| Rail | Load | Typical | Peak |
|---|---|---|---|
| 3.3 V | ESP32-C3 Wi-Fi/BLE module | 80–150 mA active estimate | 345 mA Wi-Fi TX peak; supply sized for >=500 mA per datasheet |
| 3.3 V | SHT41 sensor | =2.7 A saturation current, low DCR preferred. |
Open layout constraints for next phase
- Place ESP32-C3-WROOM-02 antenna at board edge with antenna keepout clear of copper, traces, components, and enclosure metal.
- Place SHT41 away from heat sources: buck regulator, eFuse, ESP32 module, and status LED.
- Keep AP63203 input cap, inductor, bootstrap cap, and output caps tightly looped.
- Put USB ESD protection close to the USB-C receptacle.
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