Temperature and Humidity Sensor Node Design
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I’ve prepared a plan to build your low‑power Wi‑Fi + BLE T/RH sensor node powered by USB‑C.
- Steps:
- Add MCU module (dual‑radio Wi‑Fi 802.11 b/g/n + BLE 5.x), digital T/RH sensor, and USB‑C receptacle.
- Implement power path: CC resistors, reverse/OVP/UVLO/OCP, TVS, and a low‑IQ 3.3 V regulator with decoupling.
- Add RF/antenna (or certified module), programming header, status LED, and test pads.
- Wire USB‑C, power rails, I2C, and control nets; add pulls/filters; run ERC/DRC.
- Prepare PCB footprints and RF‑aware placement; run auto‑layout and review.
Click Start on the plan bar to execute. Preferences before we begin:
- MCU: certified module (smaller/faster to certify) or chip‑down?
- Sensor: SHT4x/SHT3x, HDC3xxx, or your preference?
- Size constraints or enclosure?
- Any specific protection ICs (ideal diode/OVP switch, eFuse), or should I pick proven parts?
Plan
- Design a consumer-grade, low-power environmental sensor node powered by USB-C (5 V) input, capable of handling 0.5–3 A sources. The node will integrate an ultra-low-power dual‑radio MCU supporting 802.11 b/g/n Wi‑Fi and BLE 5.x, paired with a digital temperature/humidity sensor. The design will include robust USB-C power input protection features such as reverse polarity, over-voltage, under-voltage lockout, and over-current protection, along with necessary supply conditioning and RF components.
#Implementation plan
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Key Components Selection and Addition
- Select and add an ultra‑low‑power dual‑radio MCU with Wi‑Fi (802.11 b/g/n) and BLE 5.x support (e.g., ESP32 series) to the project.
- Select and add a digital temperature/humidity sensor (e.g., SHT3x) to the schematic.
- Select and add a USB‑C receptacle and related USB‑C configuration channel (CC) circuitry.
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**Power Management and Protection
- Design and add a power chain starting with a USB‑C input section:
- Include CC resistors and a USB‑C configuration circuit to negotiate proper power delivery.
- Add power input protection components for reverse polarity, over-voltage (using TVS diodes), under-voltage lockout, and over-current conditions.
- Select and add a 3.3 V regulator with proper decoupling circuits and passives for low-noise operation.
- Design and add a power chain starting with a USB‑C input section:
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Supporting Components and Connectivity
- Add necessary decoupling capacitors, resistors, and TVS diodes on power rails.
- Provide proper clock components (e.g., crystal oscillator if required by the MCU) and program/debug connectors.
- Add status indicator LED(s) and test pads for functional verification.
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RF and Layout Considerations
- Include the design of an RF antenna or plan to integrate a certified module, ensuring proper RF matching and layout practices for low-power operation.
- Define placement guidelines in the schematic and PCB layout (e.g., component spacing and thermal management hints).
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Schematic Integration and Verification
- Wire connections between the MCU, sensor, USB‑C input, power management, and RF components ensuring proper net assignments.
- Run ERC/DRC reviews to validate circuit functionality and protection compliance.
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PCB Preparation
- Prepare PCB footprints and assign stackup defaults considering RF routing and power integrity.
- Run auto‑layout for initial component placement and routing while reviewing trace widths and impedance standards.
#Success criteria
- Complete schematic incorporating the ultra‑low‑power MCU, digital T/RH sensor, and full USB‑C power input protection scheme.
- Verification of power protection circuitry (reverse, over-voltage, under-voltage, and over-current) and proper 3.3 V regulation.
- Verified ERC/DRC with no errors and a layout that adheres to RF and low-power design best practices.
Choose certified MCU module
Pick sensor family
Define enclosure constraints
Select protection approach
Clarify USB-C behavior
172 days
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