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Board Bring-Up Plan — ESP32-C6 CO2 Sensor
Prerequisites
- Equipment: multimeter, current-limited USB supply, oscilloscope if available, USB-C cable, PlatformIO host.
- Battery: protected 1-cell LiPo, nominal 3.7 V, connector polarity verified before plugging into J2.
1. Visual Inspection
- Inspect U3 BQ24074, U4 TPS63001, U1 ESP32-C6-WROOM-1, U2 SCD41, J1 USB-C, J2 LiPo connector, D1 USB ESD, F1 PTC.
- Verify no bridges around U3/U4 QFN pins and USB-C pads.
2. Power Rail Verification
Table
| Rail | Source | Expected | Measure At | Current Limit | Pass Criteria |
|---|---|---|---|---|---|
| USB_VBUS_RAW | J1 VBUS before F1 | 5.0 V | J1/F1 pin 1 | 100 mA first power | 4.75-5.25 V |
| VBUS_PROT | F1 output | 5.0 V minus fuse drop | U3 IN/C1 | 100 mA first power | within 0.2 V of USB_VBUS_RAW at light load |
| VBAT | J2 / U3 BAT | 3.0-4.2 V battery | J2 P1/C2 | battery limited | correct polarity, no short |
| SYS | U3 OUT | battery or USB system rail | C3/U4 VIN | 100 mA first power | ~VBAT on battery, ~4.4 V on USB |
| 3V3 | U4 VOUT | 3.3 V | C5/C6/U1 pin 2 | 100 mA first power | 3.14-3.47 V |
Procedure: check resistance from 3V3, SYS, VBAT, and VBUS_PROT to GND before power. Power from USB first with no battery, then repeat with battery installed.
3. Critical Signals
Table
| Signal | Expected Idle | Notes |
|---|---|---|
| ESP_EN | High, near 3.3 V | SW1 pulls low for reset |
| ESP_BOOT / IO9 | High, near 3.3 V | SW2 pulls low for bootloader |
| I2C_SDA / I2C_SCL | High, near 3.3 V idle | Pulled up by R10/R11 |
| USB_D_PLUS / USB_D_MINUS | USB activity during enumeration | Route/check as differential pair in layout |
| VBAT_SENSE | VBAT/2 | 4.2 V battery gives ~2.1 V ADC input |
4. Programming and Functional Tests
- Connect USB-C and verify 3V3 before flashing.
- Flash the firmware from the Firmware Starter file.
- Confirm USB serial enumeration and boot logs.
- Run I2C/SCD41 read test; expect CO2 in plausible indoor range after sensor warm-up.
- Confirm status LED D2 toggles during successful readings.
- Confirm ADC battery reading roughly equals measured VBAT.
- Verify LiPo charging behavior with a current-limited USB source and monitor U3 temperature.
5. Pass/Fail Summary
Table
| Section | Result | Notes |
|---|---|---|
| Visual inspection | [ ] Pass / [ ] Fail | |
| Power rails | [ ] Pass / [ ] Fail | |
| USB/programming | [ ] Pass / [ ] Fail | |
| SCD41 sensing | [ ] Pass / [ ] Fail | |
| Battery charging | [ ] Pass / [ ] Fail | |
| Sleep/runtime test | [ ] Pass / [ ] Fail |
Open Layout Recommendations
- Add test points for GND, VBUS_PROT, SYS, VBAT, 3V3, ESP_EN, I2C_SDA, I2C_SCL.
- Keep ESP32-C6 antenna area clear per Espressif module layout guidance.
- Keep U4 inductor and switching loop compact; place C4/C5/C6 close to U4.
Prerequisites
1. Visual Inspection
2. Power Rail Verification
3. Critical Signals
4. Programming and Functional Tests
5. Pass/Fail Summary
Open Layout Recommendations
