Power Distribution Schematic Design

flux

Initial PCB placement is complete, with no overlap or out-of-board placement issues: thermocouple connectors along the top edge, battery/fuse/regulator on the left, fan/servo connectors and drivers on the right, ESP32 centered, and MAX31855 devices grouped near the ESP32. Estimated time saved vs. manual EDA workflow: ~2–4 hours.
Open items:
  • Airwires remain because routing was intentionally not performed.
  • Placement concern: the design spans most of the 160 mm board width, so keep BAT_12V routing wide and thermocouple traces physically separated from fan/servo current paths during routing.
Suggested next steps:
  1. Set high-current trace-width rules for BAT_12V, FAN_GND, and servo power.
  2. Add/confirm GND plane setup on the 4-layer stackup.
  3. Route power first, then sensitive thermocouple/SPI signals.
  4. Run DRC after routing.

flux

Final hardware review is complete and saved as Final Hardware Design Review Before PCB Routing. Highest-priority items before routing are reverse-polarity protection, fuse/current sizing, LM2596 module-vs-IC confirmation, and high-current trace-width rules; no design changes were made.
Add protections and rules
Add reverse protection
Set trace rules
Verify LM2596
Explain fuse sizing

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Power Subsystem and Bring-Up Notes
Scope Completed
  • Created the power-only schematic for the DIY Grill Controller AI project.
  • Added battery input, input fuse, 12V distribution, 5V buck conversion, ESP32 5V input, ESP32-derived 3V3 distribution, and common GND.
  • Signal pins were intentionally not connected.
Implemented Power Nets
  • BAT_IN: raw battery positive from J1 pin 1 to F1 pin 1.
  • BAT_12V: fused 12V rail from F1 pin 2 to LM2596 input, servo connector, blower connector, and 12V bulk capacitors.
  • 5V: LM2596 output to ESP32 5V pin and local 5V capacitors.
  • 3V3: ESP32 3V3 pin to all five MAX31855 VCC pins and their 100nF local decoupling capacitors.
  • GND: common return tying battery negative, buck ground, ESP32 grounds, thermocouple module grounds, servo/fan grounds, and all decoupling capacitors.
Components / Stand-ins Used
  • J1: battery input terminal block.
  • F1: fused battery-positive input protection.
  • U2: LM2596 regulator IC symbol used as a stand-in for the LM2596 buck converter module.
  • U1: ESP32-DevKitC used as a stand-in for ESP32 DevKit V1 USB-C.
  • U3-U7: MAX31855KASA+ IC symbols used as stand-ins for five MAX31855 thermocouple modules.
  • J2: STS3215 smart servo power connector, power only.
  • J3: 12V blower fan power connector, power only.
Decoupling Added
  • C1: 470uF / 25V bulk on fused BAT_12V.
  • C2: 100uF / 25V LM2596 input bypass.
  • C3: 220uF / 10V 5V rail bulk.
  • C4: 10uF / 10V ESP32 5V local bypass.
  • C5-C9: 100nF / 10V local 3V3 decoupling for MAX31855 modules.
  • C10: 470uF / 25V servo 12V bulk.
  • C11: 220uF / 25V blower 12V bulk.
Verification Result
  • Confirmed power nets exist and are named BAT_12V, 5V, 3V3, and GND.
  • Confirmed battery positive enters through fuse F1 before joining BAT_12V.
  • Confirmed all requested loads and modules share common GND.
  • Intentional no-connect markers were added to signal/control pins to keep this schematic power-only.
  • Remaining review item: Flux reports U1:VP as a missing power input. This is a false positive for this power-only stage because VP is an ESP32 ADC/header pin and was intentionally left unconnected with the other signal pins.
Bring-Up Checklist
  1. With battery disconnected, verify no short between BAT_12V and GND, 5V and GND, and 3V3 and GND.
  2. Connect current-limited bench supply to J1 instead of the battery for first power-up.
  3. Verify voltage after F1 on BAT_12V.
  4. Verify LM2596 output is adjusted to 5.0V before installing/connecting the ESP32.
  5. Verify ESP32 3V3 pin is approximately 3.3V before attaching MAX31855 modules.
  6. Add servo/fan loads one at a time and check for brownouts or excessive voltage sag.
  7. After signal wiring is added, re-run ERC and remove intentional no-connects where pins become used.

  • Scope Completed

  • Implemented Power Nets

  • Components / Stand-ins Used

  • Decoupling Added

  • Verification Result

  • Bring-Up Checklist

DIY Grill Controller AI

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