CO2 Meter

Worked for 4 mins 42 sec

I found the first ESP32 module library part was a reusable submodule without the EN pin exposed, so I’m replacing it with an actual ESP32-S3-MINI-1-N8 module part that has the full manufacturer pinout before wiring.

Worked for 3 mins 43 sec

flux

Datasheet checks are complete: SCD41 VDD/VDDH must share the

Worked for 6 mins 58 sec

flux

The full logical schematic is wired now, including USB-C power/data, 3.3 V regulation, SCD41/OLED I2C, RGB indication, boot/reset, and debug header. I’m running checks and will fix remaining electrical issues next.

Worked for 6 mins 48 sec

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

The demo is finished. It didn't use any of your included AI usage. This is a real Flux project now, you can continue working on it.

Files

Schematic

Layout

Preview

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