USB-C Temperature and Humidity Sensor Design

0:12

Work done

Updated the project description to reflect the low-power USB-C environmental and biosensor node requirements.
Added and wired the major schematic blocks: J1 USB-C input, U5 protected 5V entry, U4 3.3V regulation, U1 ESP32-C3 Wi-Fi/BLE module, U2 temperature/humidity sensor, U3 EEG AFE, IC1 PPG sensor, plus external interfaces J2 and J3.
Implemented USB-C sink behavior with 5.1 kΩ CC pull-downs on R1 and R2, VBUS decoupling, ESD protection on D1, and protected input distribution through U5.
Created the main interconnects for power, I2C, SPI, reset/enable, EEG channels, and PPG interrupt signaling.
Initialized the PCB layout as a 60 mm x 45 mm rounded rectangle with a Standard 4 Layer stackup and basic board-level rules.

Success criteria review

✅ Project description now reflects USB-C power, protection intent, Wi-Fi/BLE, environmental sensing, Bluetooth syncing support, and EEG/PPG interfacing.
✅ Schematic now includes the major requested functional blocks and core interconnections for power, MCU, sensor, and biosignal interfaces.
✅ Layout has been created and prepared with a 4-layer stackup and board rules for further review and placement.
❌ The schematic still has cleanup items on floating or reserved pins, and some biosensor/reference nets remain first-pass placeholders rather than fully production-ready analog circuitry.
❌ The current layout outline is smaller than the full component spread, so final placement and routing readiness still need one more pass.

Next steps I can next clean up the remaining floating pins, replace generic passives with production MPNs where needed, and resize the layout so the board is truly ready for placement and routing.

20 days

okhellothere

Add a digital temp/humidity sensor plus EEG and PPG interface blocks to the schematic. Review everything. Make sure it works for hydrophone testing, make sure the emitter is going to work in the transducer as well.

20 days

flux

1:40

Planning tool usage.

Thinking deeply about your request.

Creating an execution plan.

Formulating project context.

Working on your request.

Reviewing the bill of materials.

Analyzing the PCB layout.

Analyzing the schematic.

Working on your request.

Summarizing execution plan.

You want the current node updated so the temp/humidity, EEG, and PPG blocks are completed and reviewed, with hydrophone/transducer support folded in if it belongs on this board.

I’ve built the plan.
It covers sensor-block completion, low-noise integration review, and the acoustic subsystem decision point that changes the architecture significantly

Click Start on the plan bar to run it.

Plan

#Goal

Update the USB-C Environmental Biosensor Node by reviewing and completing the digital temperature/humidity, EEG, and PPG interface blocks, and determine how hydrophone testing and transducer emitter support should integrate with the design.

#Implementation plan

Schematic Review and Block Completion
1. Audit the existing schematic to verify the SHT31 temperature/humidity sensor interface is fully implemented with proper digital I²C interfacing and supporting components.
2. Review the ADS1299 EEG block ensuring all required analog front-end support (e.g., filters, biasing) is correctly added.
3. Confirm the MAX30102 PPG sensor block including proper power supply decoupling and digital interfacing.
System-Level Integration
1. Check system-level power distribution, grounding schemes, and interface readiness to support the revised sensor blocks, ensuring low-noise performance especially for the EEG block.
2. Update connections and signal routing for improved signal integrity across the digital sensor interfaces.
Hydrophone and Transducer Integration Assessment
1. Determine and document if hydrophone testing and transducer emitter support should be integrated on the current board or managed as a separate subsystem based on system-level constraints.
2. If integrated, design and add interface circuitry for acoustic measurements (e.g., amplification and filtering for hydrophone input, drive circuitry for the transducer emitter).
3. Adjust the schematic and layout to incorporate these acoustic testing modules while maintaining low-noise separation from sensitive sensor blocks.
Schematic and PCB Update
1. Implement the schematic changes reflecting completed sensor block interfaces and any new circuitry for hydrophone/transducer support.
2. Update the 4-layer PCB layout to accommodate new components and ensure proper separation of analog and digital domains.
3. Run a complete design review pass to verify electrical connections, layout constraints, and manufacturability.

#Success criteria

All temperature/humidity, EEG, and PPG blocks are complete, verified, and integrated correctly in the schematic.
System-level power, grounding, and signal routing meet the performance requirements for low-noise biosensing.
A clear design decision is made on how to incorporate hydrophone testing and transducer emitter support, with updated schematic and PCB layout reflecting the chosen integration method.
The project is reviewed and ready for further testing and fabrication.

Check USB_CC2 routing

Keep hydrophone analog separate

Run full ERC/DRC

20 days

Reviews

Ground
A common return path for electric current. Commonly known as ground.
jharwinbarrozo
20.5M
Net Portal
Wirelessly connects nets on schematic. Used to organize schematics and separate functional blocks. To wirelessly connect net portals, give them same designator. #portal
jharwinbarrozo
43.0M
Power Net Portal
Wirelessly connects power nets on schematic. Identical to the net portal, but with a power symbol. Used to organize schematics and separate functional blocks. To wirelessly connect power net portals, give them the same designator. #portal #power
jharwinbarrozo
11.4M
Generic Resistor
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
jharwinbarrozo
1.5M
Generic Capacitor
A generic fixed capacitor ideal for rapid circuit topology development. You can choose between polarized and non-polarized types, its symbol and the footprint will automatically adapt based on your selection. Supported options include standard SMD sizes for ceramic capacitors (e.g., 0402, 0603, 0805), SMD sizes for aluminum electrolytic capacitors, and through-hole footprints for polarized capacitors. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard capacitor values: 1.0pF, 10pF, 100pF, 1000pF, 0.01uF, 0.1uF, 1.0uF, 10uF, 100uF, 1000uF, 10000uF 1.1pF, 11pF, 110pF, 1100pF 1.2pF, 12pF, 120pF, 1200pF 1.3pF, 13pF, 130pF, 1300pF 1.5pF, 15pF, 150pF, 1500pF, 0.015uF, 0.15uF, 1.5uF, 15uF, 150uF, 1500uF 1.6pF, 16pF, 160pF, 1600pF 1.8pF, 18pF, 180pF, 1800pF 2.0pF, 20pF, 200pF, 2000pF 2.2pF, 22pF, 220pF, 2200pF, 0.022uF, 0.22uF, 2.2uF, 22uF, 220uF, 2200uF 2.4pF, 24pF, 240pF, 2400pF 2.7pF, 27pF, 270pF, 2700pF 3.0pF, 30pF, 300pF, 3000pF 3.3pF, 33pF, 330pF, 3300pF, 0.033uF, 0.33uF, 3.3uF, 33uF, 330uF, 3300uF 3.6pF, 36pF, 360pF, 3600pF 3.9pF, 39pF, 390pF, 3900pF 4.3pF, 43pF, 430pF, 4300pF 4.7pF, 47pF, 470pF, 4700pF, 0.047uF, 0.47uF, 4.7uF, 47uF, 470uF, 4700uF 5.1pF, 51pF, 510pF, 5100pF 5.6pF, 56pF, 560pF, 5600pF 6.2pF, 62pF, 620pF, 6200pF 6.8pF, 68pF, 680pF, 6800pF, 0.068uF, 0.68uF, 6.8uF, 68uF, 680uF, 6800uF 7.5pF, 75pF, 750pF, 7500pF 8.2pF, 82pF, 820pF, 8200pF 9.1pF, 91pF, 910pF, 9100pF #generics #CommonPartsLibrary
jharwinbarrozo
1.5M
Generic Inductor
A generic fixed inductor suitable for rapid circuit topology development. The footprint automatically adapts based on the selected package, supporting standard SMD sizes (e.g., 0402, 0603, 0805) as well as well-known inductor packages such as SDR1806, PA4320, SRN6028, and SRR1260. Standard inductor values: 1.0 nH, 10 nH, 100 nH, 1.0 µH, 10 µH, 100 µH, 1.0 mH 1.2 nH, 12 nH, 120 nH, 1.2 µH, 12 µH, 120 µH, 1.2 mH 1.5 nH, 15 nH, 150 nH, 1.5 µH, 15 µH, 150 µH, 1.5 mH 1.8 nH, 18 nH, 180 nH, 1.8 µH, 18 µH, 180 µH, 1.8 mH 2.2 nH, 22 nH, 220 nH, 2.2 µH, 22 µH, 220 µH, 2.2 mH 2.7 nH, 27 nH, 270 nH, 2.7 µH, 27 µH, 270 µH, 2.7 mH 3.3 nH, 33 nH, 330 nH, 3.3 µH, 33 µH, 330 µH, 3.3 mH 3.9 nH, 39 nH, 390 nH, 3.9 µH, 39 µH, 390 µH, 3.9 mH 4.7 nH, 47 nH, 470 nH, 4.7 µH, 47 µH, 470 µH, 4.7 mH 5.6 nH, 56 nH, 560 nH, 5.6 µH, 56 µH, 560 µH, 5.6 mH 6.8 nH, 68 nH, 680 nH, 6.8 µH, 68 µH, 680 µH, 6.8 mH 8.2 nH, 82 nH, 820 nH, 8.2 µH, 82 µH, 820 µH, 8.2 mH #generics #CommonPartsLibrary
jharwinbarrozo
15.8k
Terminal
An electrical connector acting as reusable interface to a conductor and creating a point where external circuits can be connected.
natarius
RMCF0805JT47K0
47 kOhms ±5% 0.125W, 1/8W Chip Resistor 0805 (2012 Metric) Automotive AEC-Q200 Thick Film #forLedBlink
jharwinbarrozo
1.2M
875105359001
10uF Capacitor Aluminum Polymer 20% 16V SMD 5x5.3mm #forLedBlink #commonpartslibrary #capacitor #aluminumpolymer #radialcan
jharwinbarrozo
1.2M
CTL1206FYW1T
Yellow 595nm LED Indication - Discrete 1.7V 1206 (3216 Metric) #forLedBlink
jharwinbarrozo
1.1M

Project Name

USB-C Environmental Biosensor Node

Description

Low-power USB-C 5V environmental sensor node with robust input protection, ESP32 Wi-Fi/BLE connectivity, digital temperature/humidity sensing, Bluetooth peripheral syncing, and EEG/PPG sensor interfaces for prototype biosignal acquisition.

Properties

Properties describe core aspects of the project.

Pricing & Availability

Distributor	Qty 1
Arrow	$34.09–$36.66
Digi-Key	$27.57–$48.00
LCSC	$60.06
Mouser	$45.78
TME	$2.55
Verical	$3.61–$7.69

Controls

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