ESP32-S3 Firmware Refinement
move the j2 to the top left edge but keep a clearance of around 0.73cm from the edge. same applies for the other compondtes already on the top edge make sure theres that 0.73cm clearance along that edge. move both switchs down to the bottom inbeween the esp32 and J1. also make the traces neat no lines going over ccomponets and also fix all the eroors theres cuts and deadends to the traces
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I’ll adjust the placement as requested, then remove stale/cut/dead-end traces caused by moving parts and rerun routing/review. I’ll keep J2 and the top-edge parts about 7.3 mm from the top edge, and move RST_SW/BOOT_SW down between the ESP32 and J1.
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1/5 Inspect current component positions, board bounds, and review errors
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Completed 7 design checks — found 4 issues.
Read layout.
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2/5 Move J2/top-edge components to maintain 7.3 mm top-edge clearance and move switches near bottom between ESP32 and J1
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I’m out of execution credits, so I had to stop after the placement step.
Completed:
- Moved J2 to the top-left edge area with about 7.3 mm clearance from the board edge.
- Adjusted the other top-edge components so they keep that same top-edge clearance.
- Moved RST_SW and BOOT_SW down between the ESP32-S3 module and USB-C connector J1.
- Preserved the ESP32 antenna orientation facing the bottom edge.
- Placement now has no overlap or out-of-bounds issues.
Still to do:
- Delete stale/dead-end traces created by moving components.
- Re-route the affected nets.
- Clean up trace paths so they don’t run awkwardly over/through component areas.
- Rerun review and fix the remaining routing errors, including the USB D+/D− airwires.
Clean reroute traces
Run DRC review
Route USB pair
Check trace crossings
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Project Specification — ESP32 Relay Controller
Project Overview
- Status: Draft schematic implementation
- Device: 12V-powered ESP32-S3 relay controller with one isolated dry-contact relay output.
- Primary requirement: USB-C is for data/programming only; the board is powered from a separate 12V input.
Intended Use
- Hobbyist/prototype control board for switching a single external dry contact.
- External system provides 12V DC input power.
- USB-C connects to a computer for firmware flashing/debugging, not for powering the board.
What the Device Should Do
- Power the ESP32 from the 12V input through an onboard 3.3V regulator.
- Let the ESP32 control one 12V relay coil.
- Expose relay COM/NO/NC contacts as an isolated dry-contact terminal.
- Provide USB-C D+/D- data connection to the ESP32-S3 native USB interface.
- Provide BOOT and RESET buttons for ESP32 bring-up.
Main Features
- ESP32-S3-WROOM module with WiFi/BLE available.
- 12V input screw terminal.
- 3.3V, 2A fixed buck regulator.
- 12V relay with SPDT dry-contact output.
- MOSFET low-side relay driver with flyback diode.
- USB-C data-only port with CC pull-downs and USB data ESD protection.
System Architecture
Diagram
Hardware Subsystems
Power
- 12V input enters at J2.
- AP63203WU-7 generates the 3.3V ESP32 rail.
- Regulator support parts follow the AP63203 datasheet: 10uF input cap, 3.9uH inductor, 2x22uF output caps, 100nF bootstrap cap.
Compute and USB
- ESP32-S3-WROOM-1-N16R8 is used so USB-C D+/D- can connect directly to native USB pins IO20/IO19.
- EN has 10k pull-up and 1uF delay capacitor.
- GPIO0 has a boot pull-up and BOOT button to ground.
Relay Output
- 12V relay coil is driven by a logic-level N-channel MOSFET from ESP32 GPIO4.
- Flyback diode protects the MOSFET from relay coil inductive kick.
- COM, NO, and NC are exposed at the 3-pin terminal as isolated dry-contact outputs.
Interfaces and Connections
Table
| Interface | Connector/Net | Notes |
|---|---|---|
| 12V input | J2 | Pin 1 = +12V, pin 2 = GND assumption |
| USB data | J1 | D+/D- only to ESP32 native USB; VBUS is not tied to board power |
| Relay dry contact | J3 | Pin 1 = COM, Pin 2 = NO, Pin 3 = NC |
| Relay control GPIO | ESP32 IO4 | Drives MOSFET gate through 100 ohm resistor |
| Boot | ESP32 IO0 | BOOT button pulls low |
| Reset/enable | ESP32 EN | RESET button pulls low |
Power and Runtime Expectations
- No battery or runtime target specified.
- Board runs whenever external 12V is present.
- USB-C VBUS is treated only as connector-side USB voltage for ESD/reference, not as a power source.
Power Tree and Power Budget
Table
| Rail | Load | Estimated Current |
|---|---|---|
| 3.3V | ESP32-S3 WiFi peaks | 500mA design peak |
| 12V | Relay coil ACNM1112 | 53.3mA rated |
| 12V | Buck input for 3.3V rail | About 162mA at 3.3V/500mA, 85% efficiency |
| 12V | Total design peak | About 216mA plus margin |
Manufacturing and Assembly Expectations
- SMD design by default, with through-hole screw terminals and relay.
- Relay and terminals are larger through-hole parts suitable for easier wiring.
- ESP32 antenna must be placed at the PCB edge with copper keepout during layout.
Firmware-Relevant Hardware Requirements
- ESP32-S3 native USB Serial/JTAG on IO19/IO20.
- Relay control output on GPIO4.
- BOOT button on GPIO0 and RESET button on EN.
- Firmware should default relay off at boot.
Physical Design Expectations
- Place USB-C at board edge.
- Place 12V input and relay contact terminals at board edges for wiring access.
- Place ESP32 antenna at an outside edge with keepout.
- Keep relay contact routing isolated from logic/power where practical.
Important Design Decisions
- Used ESP32-S3 module instead of bare ESP32 chip to avoid RF matching complexity.
- Used buck regulator instead of LDO because 12V to 3.3V at ESP32 current would waste significant heat.
- USB-C does not power the board, matching the user's requirement.
- Relay contacts are dry and isolated from the ESP32 logic supply.
Assumptions
- 12V input supply can provide at least 0.5A.
- Relay contact rating is more than enough for the intended dry-contact signal, but the external load voltage/current was not specified.
- USB-C is device/UFP data connection to a computer, not USB host mode.
- Default PCB style is compact SMD unless the user requests hand-solder-only parts.
Change Notes
- Initial schematic architecture created from the user's requirements.
- Added ESP32-S3, USB-C data-only, 12V buck regulator, relay driver, and dry-contact output blocks.
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