Temperature and Humidity Sensor Node Design

flux

0:00

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:
    • VBUS_RAW: J1 -> U1 IN
    • VBUS_PROT: U1 OUT -> buck U2 VIN
  • 3.3 V rail generated by low-Iq buck U2 + inductor L1, with bulk/decoupling caps (C1 etc.) tied to VBUS_PROT, 3V3, and GND.
Sub-5 uA sleep sensor domain (power gated)
  • Sensor rail switched by load switch U6:
    • 3V3_TO_LOADSW: U2 VOS -> U6 IN1
    • SENSOR_3V3: U6 OUT1 -> sensor U5 VDD
    • SENSOR_EN: U4 IO4 -> U6 EN1
MCU + sensor + buses
  • MCU/radio module U4 (Wi-Fi 2.4 GHz + BLE 5.x class module) powered from 3V3.
  • Temp/RH sensor U5 on I2C:
    • I2C_SCL: U4 IO5 U5 SCL with pull-up R3
    • I2C_SDA: U4 IO6 U5 SDA with pull-up R4
    • Pull-ups go to 3V3 (per KB default 4.7k).
USB data-line ESD (cap < 1 pF/line)
  • USB D+/D- from J1 protected with:
    • Series resistors R5, R6
    • Low-cap ESD diodes D1, D2 to GND
RF front-end placeholder (needs final RF pin confirmation)
  • 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).
Checks + status
  • 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.
Gaps to meet your Success Criteria (remaining work)
  • 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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  • Ground
    Ground
    A common return path for electric current. Commonly known as ground.
    jharwinbarrozo
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  • Generic Resistor
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    A generic fixed resistor ideal for rapid circuit topology development. Its footprint automatically adapts based on the selected package case code—supporting 0402, 0603, 0805, 1203, and many other standard SMD packages, as well as axial horizontal and vertical configurations. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard resistor values: 1.0 ohm, 10 ohm, 100 ohm, 1.0k ohm, 10k ohm, 100k ohm, 1.0M ohm 1.1 ohm, 11 ohm, 110 ohm, 1.1k ohm, 11k ohm, 110k ohm, 1.1M ohm 1.2 ohm, 12 ohm, 120 ohm, 1.2k ohm, 12k ohm, 120k ohm, 1.2M ohm 1.3 ohm, 13 ohm, 130 ohm, 1.3k ohm, 13k ohm, 130k ohm, 1.3M ohm 1.5 ohm, 15 ohm, 150 ohm, 1.5k ohm, 15k ohm, 150k ohm, 1.5M ohm 1.6 ohm, 16 ohm, 160 ohm, 1.6k ohm, 16k ohm, 160k ohm, 1.6M ohm 1.8 ohm, 18 ohm, 180 ohm, 1.8K ohm, 18k ohm, 180k ohm, 1.8M ohm 2.0 ohm, 20 ohm, 200 ohm, 2.0k ohm, 20k ohm, 200k ohm, 2.0M ohm 2.2 ohm, 22 ohm, 220 ohm, 2.2k ohm, 22k ohm, 220k ohm, 2.2M ohm 2.4 ohm, 24 ohm, 240 ohm, 2.4k ohm, 24k ohm, 240k ohm, 2.4M ohm 2.7 ohm, 27 ohm, 270 ohm, 2.7k ohm, 27k ohm, 270k ohm, 2.7M ohm 3.0 ohm, 30 ohm, 300 ohm, 3.0K ohm, 30K ohm, 300K ohm, 3.0M ohm 3.3 ohm, 33 ohm, 330 ohm, 3.3k ohm, 33k ohm, 330k ohm, 3.3M ohm 3.6 ohm, 36 ohm, 360 ohm, 3.6k ohm, 36k ohm, 360k ohm, 3.6M ohm 3.9 ohm, 39 ohm, 390 ohm, 3.9k ohm, 39k ohm, 390k ohm, 3.9M ohm 4.3 ohm, 43 ohm, 430 ohm, 4.3k ohm, 43K ohm, 430K ohm, 4.3M ohm 4.7 ohm, 47 ohm, 470 ohm, 4.7k ohm, 47k ohm, 470k ohm, 4.7M ohm 5.1 ohm, 51 ohm, 510 ohm, 5.1k ohm, 51k ohm, 510k ohm, 5.1M ohm 5.6 ohm, 56 ohm, 560 ohm, 5.6k ohm, 56k ohm, 560k ohm, 5.6M ohm 6.2 ohm, 62 ohm, 620 ohm, 6.2k ohm, 62K ohm, 620K ohm, 6.2M ohm 6.8 ohm, 68 ohm, 680 ohm, 6.8k ohm, 68k ohm, 680k ohm, 6.8M ohm 7.5 ohm, 75 ohm, 750 ohm, 7.5k ohm, 75k ohm, 750k ohm, 7.5M ohm 8.2 ohm, 82 ohm, 820 ohm, 8.2k ohm, 82k ohm, 820k ohm, 8.2M ohm 9.1 ohm, 91 ohm, 910 ohm, 9.1k ohm, 91k ohm, 910k ohm, 9.1M ohm #generics #CommonPartsLibrary
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USB-C Powered Ultra-Low-Power Environmental Sensor Node (ESP32-C6 + SHT45)

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