CO2 Meter

Worked for 6 mins 51 sec

Created 5 project docs

Firmware Starter — ESP32-S3-MINI-1-N8

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MCU: U1, ESP32-S3-MINI-1-N8 Framework: Arduino via PlatformIO

Schematic Verification Report — USB CO2 Air Monitor

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Schematic-level electrical checks passed for the selected ERC/passive/component review set after wiring and no-connect cleanup. USB-C input ...

Board Bring-Up Plan — USB CO2 Air Monitor

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Equipment: USB current meter or current-limited 5 V supply, DMM, oscilloscope if available, USB-C cable, computer with PlatformIO/esptool. F...

Technical Construction File Notes — USB CO2 Air Monitor

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Draft notes for a USB desktop product containing an ESP32-S3 Wi-Fi/BLE module. Wireless firmware is disabled by default in the starter firmw...

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flux

Completed the schematic for the USB-powered desktop CO₂ monitor and verified the schematic-focused ERC/passive/component checks are clean. Key docs are here: Schematic Verification Report, Schematic Wiring Summary, Firmware Starter, Board Bring-Up Plan, and Power Budget Analysis.

Open items:

PCB layout/routing is not started, so board DRC airwires are expected.
Generic passives still need final package/MPN selection before manufacturing.
ESP32 antenna keepout must be enforced during layout.

Suggested next steps:

Set compact board size/stackup and place components.
Route USB, I2C, power, and LED nets.
Assign production MPNs/footprints to generic passives.
Run full PCB DRC and prepare manufacturing outputs.

Layout and production prep

Start PCB layout

Assign passive MPNs

Route the board

Run layout DRC

Demo Complete

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Files

Schematic

Layout

3D View

Power Budget Analysis — USB CO2 Air Monitor

Summary

The design uses a single 3.3 V rail derived from USB 5 V through an AP2112K-3.3 600 mA LDO. Expected typical 3.3 V load is about 127 mA; conservative worst coincident transient budget is about 497 mA.

Load Table

Table

Rail	Component	Typical	Peak / transient	Notes
3.3 V	ESP32-S3-MINI-1	80 mA	240 mA	WiFi not required; native USB + I2C monitor workload.
3.3 V	Sensirion SCD41/SCD4x CO2 sensor	15 mA	205 mA	Measurement pulses; average lower in periodic mode.
3.3 V	SSD1306 OLED module	20 mA	30 mA	Depends on pixel fill/brightness.
3.3 V	RGB status LED	5–10 mA	20 mA	Use PWM dimming/current-limited channels.
3.3 V	Pull-ups/support	<2 mA	<2 mA	I2C and boot/CC networks.
3.3 V total		~127 mA	~497 mA	Conservative transient budget.

USB Input Current

For an LDO, input current is approximately output current. USB input current budget is therefore ~127 mA typical and up to ~497 mA transient, within USB 2.0 500 mA design target if firmware avoids sustained WiFi TX/high LED current during sensor pulses.

LDO Thermal Check

Typical dissipation: (5.0 V - 3.3 V) × 0.127 A ≈ 0.22 W.
Worst coincident transient: (5.0 V - 3.3 V) × 0.497 A ≈ 0.84 W, not acceptable as sustained SOT-23 dissipation.

Design Rule

Keep normal firmware in USB/display/CO2-only mode with WiFi disabled unless explicitly enabled; dim the RGB LED. If later adding sustained WiFi/cloud telemetry, evaluate a buck regulator or larger thermal footprint.

Summary
Load Table
USB Input Current
LDO Thermal Check
Design Rule