Temperature and Humidity Sensor Node Design
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What is now built (schematic)
Power + protection (USB-C 0.5 A to 3 A capable)
- USB-C input via J1 with Rd terminations R1 and R2 (5.1 k) on CC1/CC2.
- Robust VBUS protection using eFuse U1 (reverse blocking + OVP/UVLO/OCP in one device). VBUS path:
- 3.3 V rail generated by low-Iq buck U2 + inductor L1, with bulk/decoupling caps (C1 etc.) tied to
VBUS_PROT,3V3, andGND.
- Sensor rail switched by load switch U6:
- MCU/radio module U4 (Wi-Fi 2.4 GHz + BLE 5.x class module) powered from
3V3. - Temp/RH sensor U5 on I2C:
- Chip antenna Y1 with placeholder pi/match parts C11, L2, C12.
- Important: right now the feed is wired to U4 IO15, which is almost certainly not the RF pin. We need to reconnect this to the module’s actual RF output pin/net (once we confirm it in the symbol/pins).
- DRC “Missing Footprints” is clean (I had to park a problematic load-switch symbol as U3_OLD_DO_NOT_USE and exclude it from BOM/PCB to clear the check).
- PCB layout exists only as an unplaced parts list (no board outline/placement/routing yet), so exports failed:
- BOM export failed (tool error).
- STEP export failed because there is no routable/defined layout yet.
- RF layout + matching is not “verified” yet and the RF net is not connected to the correct pin on U4.
- Programming/debug interface is not added yet (no USB-UART/JTAG header/boot buttons). This is required for practical bring-up.
- Layout stage isn’t complete (no placement/routing), so “prepared for manufacturing review” is not met yet, and exports cannot be produced.
If you confirm whether you want native USB (MCU USB pins) vs USB-UART, I’ll add the correct programming interface and then fix the RF pin/matching connectivity accordingly.
87 days
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