CO2 Meter
Worked for 6 mins 47 sec
Created 5 project docs
Firmware Starter — ESP32-S3-MINI-1-N8
MCU: U1, ESP32-S3-MINI-1-N8 Framework: Arduino via PlatformIO
Schematic Verification Report — USB CO2 Air Monitor
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
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
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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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 ACUs. You can now continue working with this project like normal.
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Board Bring-Up Plan — USB CO2 Air Monitor
Prerequisites
- Equipment: USB current meter or current-limited 5 V supply, DMM, oscilloscope if available, USB-C cable, computer with PlatformIO/esptool.
- Firmware: use the Firmware Starter document for build/flash steps.
- Safety: USB_5V maximum is standard USB 5 V; do not inject more than 6 V into U4 VIN/AP2112.
1. Visual Inspection
- Verify U1 ESP32-S3-MINI-1-N8 orientation and antenna area.
- Verify U2 SCD41 orientation and that its membrane is not touched or covered.
- Check J1 USB-C pins for bridges.
- Check D1 RGB LED orientation; it is common-anode to 3V3.
- Confirm F1, U4, D8, SW3, SW4, R10-R18, and C8/C10-C16 are populated.
2. Power Rail Verification
Table
| Rail | Source | Expected Voltage | Tolerance | Measure At | Current Limit | Pass Criteria |
|---|---|---|---|---|---|---|
| VBUS_RAW | J1 VBUS before F1 | 5.0 V | USB tolerance | J1 VBUS / F1 P1 | 500 mA initial | 4.75–5.25 V |
| USB_5V | F1 output | 5.0 V minus PTC drop | USB tolerance | F1 P2 / U4 VIN | 500 mA initial | >4.5 V during idle |
| 3V3 | U4 AP2112K-3.3 | 3.3 V | ±1.5% nominal regulator | U4 VOUT / U1 3V3 / U2 VDD | 500 mA initial | 3.25–3.35 V idle |
Procedure:
- With no power, measure resistance from USB_5V to GND and 3V3 to GND; confirm no hard short.
- Power from a current-limited USB source.
- Confirm USB_5V, then 3V3, before attempting firmware upload.
- During SCD41 measurements, watch 3V3 for droop; it should remain stable through sensor pulses.
3. Critical Signal Verification
Table
| Signal | Net | Expected State | Measure At | Notes |
|---|---|---|---|---|
| ESP32 enable | ESP_EN | High after power-up | U1 EN / R14 / SW4 | SW4 pulls low for reset; C13 gives startup delay |
| Boot strap | ESP_BOOT_IO0 | High normally, low when SW3 held | U1 IO0 / R15 / SW3 | Hold low during reset for download mode |
| USB data | USB_DP/USB_DN | USB activity during enumeration | J1/D8/U1 IO20/IO19 | Keep traces short in final PCB |
| I2C SDA/SCL | I2C_SDA/I2C_SCL | Idle high at 3.3 V | R12/R13/U2/U3 | 100 kHz starter firmware |
4. Connector and Interface Tests
Table
| Connector | Type | Pins to Verify | Test Method |
|---|---|---|---|
| J1 | USB-C receptacle | VBUS, GND, CC1/CC2, DP/DN | Continuity to F1, GND, R10/R11, D8/U1 |
| J2 | 1x6 debug/service header | 3V3, GND, TXD0, RXD0, IO0, EN | Continuity and serial output |
5. Programming and Debug Interface
Table
| Interface | Signals | Connector | Tool |
|---|---|---|---|
| Native USB Serial/JTAG | USB_DP/USB_DN | J1 | PlatformIO/esptool |
| UART0 service | UART0_TXD/UART0_RXD plus IO0/EN | J2 | 3.3 V USB-UART adapter |
Procedure:
- Connect USB-C to J1 and confirm serial device enumerates.
- Flash firmware with
pio run -t upload. - If upload fails, hold SW3, tap SW4, release SW3, and retry.
- Confirm serial monitor at 115200 baud reports SCD41 serial number and CO2 readings.
6. Functional Validation
Table
| Test | Components | Input | Expected Output | Pass Criteria |
|---|---|---|---|---|
| I2C scan | U1, U2, U3 | Firmware boot | U2 at 0x62, OLED at 0x3C | Both devices detected |
| CO2 measurement | U2 SCD41 | Ambient air | CO2 ppm after warm-up | Plausible indoor reading, typically 400–2000 ppm |
| OLED display | U3 | Firmware draw | ppm and status text | Stable visible readout |
| RGB indicator | D1/R16-R18 | CO2 thresholds | Green/yellow/red | Correct threshold color |
| Reset/boot | SW3/SW4 | Button presses | Reset/download behavior | Upload succeeds and reset restarts firmware |
Pass/Fail Summary
Table
| Test Section | Result | Notes |
|---|---|---|
| Visual Inspection | [ ] Pass / [ ] Fail | |
| Power Rails | [ ] Pass / [ ] Fail | |
| Critical Signals | [ ] Pass / [ ] Fail | |
| Connectors | [ ] Pass / [ ] Fail | |
| Programming | [ ] Pass / [ ] Fail | |
| Functional Validation | [ ] Pass / [ ] Fail |
Board Status: [ ] Ready for enclosure/layout validation / [ ] Requires rework
Prerequisites
1. Visual Inspection
2. Power Rail Verification
3. Critical Signal Verification
4. Connector and Interface Tests
5. Programming and Debug Interface
6. Functional Validation
Pass/Fail Summary
