Sorry—my previous answer was incorrect. Flux does not currently offer a native KiCad .kicad_pcb export.
In Flux’s Export menu, the PCB fabrication option is Manufacturing Files (Gerbers, etc.). These Gerber/drill files can be viewed in KiCad’s Gerber Viewer, but they are not an editable KiCad PCB project.
Currently, U4 pin 7 (PS/SYNC) is connected to the 3V3 net, along with VOUT and FB. That selects forced-PWM operation.
For this battery sensor, I recommend moving PS/SYNC to GND to enable power-save mode and reduce sleep/standby consumption. U4’s GND, PGND, and exposed pad are already connected to GND.
Battery-powered environmental sensor board using an ESP32-C6-WROOM-1 module and Sensirion SCD41 CO2/temperature sensor. The board uses USB-C for charging and USB data/programming, a single-cell 3.7 V nominal 2000 mAh LiPo pouch battery, and a buck-boost regulator for a stable 3.3 V rail.
Intended Use
Portable or wall-mounted indoor air-quality sensor prototype with Thread-based intermittent communication and deep-sleep operation between measurements.
What the Device Should Do
Measure CO2 and temperature using SCD41.
Communicate wirelessly using ESP32-C6 Thread capability.
Sleep intermittently to extend battery life.
Charge from USB-C.
Support USB-C data/programming/debug via ESP32-C6 native USB Serial/JTAG.
Main Features
ESP32-C6-WROOM-1 MCU/radio module.
SCD41 I2C CO2/temperature sensor.
USB-C 5 V sink and USB 2.0 data interface.
LiPo charging with power-path management.
3.3 V buck-boost regulator sized for ESP32 radio current bursts.
Battery voltage sense path for firmware fuel indication.
Debug: USB Serial/JTAG over native USB, BOOT and RESET controls.
Power and Runtime Expectations
The design targets intermittent Thread communication and deep sleep. Exact runtime depends on SCD41 measurement interval, ESP32-C6 radio transmit frequency, and firmware sleep strategy. The power architecture will be sized for ESP32 radio bursts rather than average current only.
Power Tree and Power Budget
Initial sizing target:
3.3 V rail peak target: at least 600 mA for ESP32-C6 radio bursts plus sensor/support margin.
Buck-boost input current worst case at low battery is expected to be roughly 0.8 A peak before margin.
USB-C non-PD operation: 5 V sink using CC pull-downs, no PD controller.
Final measured/calculated budget will be updated after datasheet values are extracted.
Manufacturing and Assembly Expectations
Default to SMD components for a compact professional PCB. USB 2.0 D+/D- should be routed as a controlled 90 ohm differential pair, preferably on a 4-layer stackup with a solid ground reference plane.
Firmware-Relevant Hardware Requirements
ESP32-C6 GPIO assignment must reserve strapping pins appropriately.
Native USB Serial/JTAG available for programming.
I2C bus for SCD41.
ADC-capable pin for battery voltage divider, divider should be switchable or high-value to limit sleep drain.
Thread communication with intermittent wake/sleep cycles.
Physical Design Expectations
ESP32-C6 module antenna must sit at a board edge with the antenna keepout free of copper, traces, components, and ground pour on all layers.
Important Design Decisions
Use buck-boost rather than LDO to preserve 3.3 V regulation across LiPo discharge.
Use USB-C native USB data into ESP32-C6 instead of external USB-UART bridge.
Use charger/power-path management so USB can power the board while charging.
Assumptions
Single-cell LiPo pouch battery with 2-pin connector and no on-board fuel gauge unless added later.
USB-C is 5 V sink only, no USB Power Delivery negotiation.
SMD assembly is acceptable.
Thread is the primary wireless protocol; Wi-Fi is not intended to remain continuously connected.
Change Notes
Initial specification created from user requirements and selected buck-boost architecture.