USB-C WiFi BLE Sensor Node Design
Thought for 9 sec
I’ll pause placement and run the DRC airwire check now, then summarize the remaining unrouted connections by net/component so we can decide what to route next.
Worked for 30 sec
DRC airwire check found 57 unrouted airwires.
Main unrouted groups:
- BUCK_SW / 3.3 V buck area: U2 SW/BST/FB, L1, C4/C5/C6/C7/C8/C10
- 3V3 rail: U2, U3, U4, decoupling caps, I2C pull-ups, boot/strap/fault pull-ups
- VBUS_RAW / VBUS_PROT: J1, D1, U1, C1/C2/C3, U2 VIN/EN
- USB-C / USB data: CC1/CC2, D+/D− through U5 to ESP32-C3
- ESP32 support: EN/reset, BOOT, GPIO2 strap, status LED, eFuse FAULT
- GND stitching/returns: several GND-related airwires remain, including one stitching via connection
Board status:
- Components are already placed on the top layer.
- Board is currently 160 × 100 mm, 4-layer, with very low density (~3.7% component fill), so routing space is generous.
Next step should be routing, but per checkpoint I’ll wait for your approval before running auto-route.
Route buck loop
List airwires
Separate DRC issues
Route USB pair
Add stitching vias
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Project Specification
Product
USB-C powered consumer temperature and humidity sensor node with Wi-Fi and Bluetooth Low Energy.
Requirements
- Power input: USB-C receptacle, 5 V default sink behavior.
- Source range planning: operate from 0.5 A to 3 A USB-C 5 V sources.
- Protection: include USB input reverse-current blocking when disabled, overvoltage protection/clamp/lockout, undervoltage lockout, overcurrent/current limiting, and fault indication where practical.
- Radio: 2.4 GHz Wi-Fi 802.11 b/g/n plus BLE 5.x dual-radio MCU/module.
- Sensor: digital I2C temperature and relative humidity sensor.
- Consumer use: compact SMD implementation, RoHS/REACH preferred, safe USB input current limiting.
Selected Architecture
USB-C receptacle -> USB-C CC pull-downs and ESD/protection -> TPS25200 eFuse -> AP63203 3.3 V buck regulator -> ESP32-C3-MINI-1-N4 + SHT45 I2C T/RH sensor.
Preliminary Part Choices
- MCU/radio: ESP32-C3-MINI-1-N4, integrated PCB trace antenna, Wi-Fi 802.11 b/g/n and BLE 5.0, 3.0 V to 3.6 V supply.
- Sensor: Sensirion SHT45-AD1B-R2, I2C address 0x44, 1.08 V to 3.6 V supply, high accuracy.
- USB-C: GCT USB4215-03-A USB 2.0 Type-C receptacle.
- eFuse/protection: TI TPS25200DRVR, current limit, OVP clamp/OVLO, UVLO, reverse blocking when disabled.
- Regulator: Diodes AP63203WU-7 fixed 3.3 V, 2 A buck regulator.
Design Notes
- ESP32-C3 external 3.3 V supply must support at least 0.5 A per Espressif recommended operating conditions.
- ESP32-C3 EN requires an RC delay; use 10 kOhm pull-up and 1 uF to GND per module datasheet guidance.
- USB-C default sink requires 5.1 kOhm pull-down resistors from CC1 and CC2 to GND.
- SHT45 uses I2C pull-ups to 3.3 V; start with 4.7 kOhm for 100 kHz or 400 kHz bus speeds.
- AP63203 3.3 V reference design uses 3.9 uH inductor, 10 uF input capacitor, 2 x 22 uF output capacitors, and 100 nF bootstrap capacitor.
Current Status
Schematic implementation in progress.
Product
Requirements
Selected Architecture
Preliminary Part Choices
Design Notes
Current Status
