CO2 Meter

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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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:
  1. Set compact board size/stackup and place components.
  2. Route USB, I2C, power, and LED nets.
  3. Assign production MPNs/footprints to generic passives.
  4. Run full PCB DRC and prepare manufacturing outputs.
Layout and production prep
Start PCB layout
Assign passive MPNs
Route the board
Run layout DRC

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Schematic Verification Report — USB CO2 Air Monitor
Status
Schematic-level electrical checks passed for the selected ERC/passive/component review set after wiring and no-connect cleanup.
Implemented Blocks
  • USB-C input J1 with CC1/CC2 5.1 kΩ sink pull-downs R10/R11.
  • USB VBUS protection through F1 resettable PTC, USB_5V bulk capacitance C8/C16, and AP2112K-3.3 regulator U4.
  • 3.3 V rail powering ESP32-S3-MINI-1-N8 U1, SCD41 U2, OLED U3, and RGB LED D1.
  • USB D+/D- routed through D8 low-capacitance ESD array to U1 IO20/IO19.
  • Shared I2C bus: U1 IO4/IO5 to U2 SCD41 and U3 SSD1306, with one pull-up pair R12/R13.
  • ESP32 boot/reset: R14/C13/SW4 on EN and R15/SW3 on GPIO0.
  • RGB indication: U1 IO6/IO7/IO8 drive common-anode RGB LED channels through R16/R17/R18.
  • Debug/service header J2 exposes 3V3, GND, UART0 TX/RX, EN, and GPIO0.
Datasheet-Critical Decisions
  • SCD41 VDD and VDDH are tied to the same 3.3 V rail close to the sensor; DNC pins are marked no-connect.
  • SCD41 peak current budget uses 205 mA at 3.3 V; AP2112 is acceptable for typical operation but not sustained worst-case high-current WiFi operation.
  • AP2112 follows datasheet VIN/VOUT ceramic capacitor requirement; additional bulk capacitance is included for sensor/display transients.
  • ESP32-S3 GPIO0 boot control, EN RC delay, USB D- on IO19, and USB D+ on IO20 follow the module datasheet.
  • USB-C is configured as a sink with independent CC pull-downs.
Verification Results
  • Floating-pin ERC warnings were cleared by wiring required pins and marking intentional NC/DNC pins.
  • Schematic electrical/passive checks queried: floating pin, no-connect, power pin, single-pin net, undriven net, driver conflict, pin-to-pin, shorted components, decoupling, pull-up/pull-down, capacitor voltage, resistor power, parts availability, MPN/datasheet/terminal component checks.
  • No ERROR/WARNING/OPEN/UNCERTAIN results remained in that schematic-focused check set.
Known Non-Schematic Items
  • PCB DRC airwires/overlapping copper are expected because layout/routing has not been started.
  • Generic passives do not yet have production MPNs assigned; finalize during physical constraints/manufacturing preparation.
  • ESP32 module RF layout still needs antenna edge placement and keepout enforcement during PCB layout.
  • Status

  • Implemented Blocks

  • Datasheet-Critical Decisions

  • Verification Results

  • Known Non-Schematic Items

USB CO2 Air Monitor

USB CO2 Air Monitor thumbnail
Compact USB-powered desktop CO₂ air quality monitor using an NDIR CO₂ sensor, microcontroller, OLED display, and visual good/moderate/poor status indication.

Properties

Properties describe core aspects of the project.

Pricing & Availability

Distributor

Qty 1

Arrow

$16.68–$17.37

Digi-Key

$0.57

HQonline

$0.30–$0.40

LCSC

$6.16–$6.34

Mouser

$25.51

TME

$0.68

Verical

$23.61–$53.67

Controls