Okay. I had to move R4 and J7. Sorry if that messes anything up.
Also. There are still issues. RT6 is only connected on one side. C23. RT4 C25. C14. Countless others are only wired up on one size.
Also, ESP32 devkits have a capacitor? Or resistor? That is wired in so you can flash firmware without the S1 and S2 buttons. And I'm not sure if the buttons are necessary, so I'm happy to save money if we can safely nix them.
I’ll re-check the layout after your R4/J7 move, distinguish PCB airwires from actual schematic one-sided wiring, then evaluate whether BOOT/RESET buttons can be removed in favor of ESP32-S3 native USB auto-download behavior.
Verified RT6/C25, RT4/C23, C14, and related passives are schematic-connected on both sides; the issue was PCB routing/airwires, not one-sided schematic wiring.
Removed optional S1 BOOT and S2 RESET buttons to save BOM/assembly cost.
Kept the important ESP32 support: R4 GPIO0 pull-up, R3 EN pull-up, and C11 EN reset-delay cap.
Cleaned stale routing from your R4/J7 move and re-routed.
Final checked categories are clean: no airwires, dangling traces, copper overlaps, invalid layers, or relevant ERC errors.
Open items:
If we want best serviceability, add tiny labeled test pads for GPIO0/BOOT and EN/RESET later; they are cheaper than buttons and useful for recovery.
Suggested next steps:
Visually inspect the routed PCB.
Add/verify GND pours and antenna keepout.
Run full manufacturing DRC before export.
Update firmware/bring-up docs to note USB flashing without BOOT/RESET buttons.
USB-C VBUS enters at J1 as VBUS_RAW, passes through MP5036 eFuse U4, and becomes 5V_PROTECTED. The 5V_PROTECTED rail feeds heater terminal positives J2-J5 and AP63203 buck regulator U3. U3 generates 3V3 for ESP32-S3 U1, STUSB4500 logic interface, Qwiic/display connector, encoder pull-ups, NTC dividers, and status LEDs.
Control Flow
ESP32-S3 U1 reads six NTC dividers via ADC pins, reads encoder/button GPIOs, communicates with STUSB4500 and the Qwiic/display connector over I2C, and switches four low-side MOSFET heater channels with PWM GPIOs. Native USB D+/D- connects U1 to J1 through ESD protection for programming and serial data.
Safety-Relevant Boundaries
USB input is assumed SELV/5 V from a certified source.
Heater outputs are low voltage but thermally safety-relevant.
Wireless transmitter is the ESP32-S3-WROOM-1 module with integrated antenna; final host integration must preserve antenna keepout.
STUSB4500 PD configuration must be limited to 5 V-only unless hardware is revised for higher-voltage operation.