PCB Schematic Design for ESP32 IoT Sensor

flux

Yes — the 24 errors are mostly PCB routing status, not 24 broken schematic connections.
What they are

Table

TypeCountMeaning
Airwires23Unrouted PCB connections between pads
ERC Missing Power1U1 pin VP is being treated as an unpowered power-input pin
I checked the project reviews directly; that’s the correct place to inspect ERC/DRC issues in Flux
Important detail
  • The 23 airwires are expected right now because the PCB has footprints placed, but the board is not routed yet.
  • The only actual schematic/ERC issue is:
    • U1 : VP flagged as “Power input not connected”
Why that ERC happened
On the ESP32 DevKit symbol, VP is likely the ADC/GPIO pin label, but its pin type in the library is probably marked as power input, so ERC is complaining even though it is not meant to be tied to a supply in your design.
What I recommend
  • Ignore the 23 airwires for now if you haven’t done PCB routing yet.
  • Fix the single ERC on U1 by either:
    • marking VP as intentionally unused with a No Connect, or
    • using a different ESP32 DevKit part whose pin typing is cleaner.
If you want, I can fix that one ERC warning on U1 for you next.
H

hannahnabill310

Fix the U1 VP ERC warning.

flux

I marked U1 VP as No Connect.
  • The change was applied successfully.
  • The ERC review is still showing the same warning, which usually means the review result has not refreshed yet.
If it still remains after a moment, the root issue is likely the ESP32 DevKit part definition treating VP as a power-input pin in a way No Connect does not suppress. In that case, the proper fix is to replace U1 with a cleaner ESP32 DevKit part, which is a multi-step change.
Replace U1 part
Check other ERC issues
Inspect U1 pins

flux

nets {
net SD_MOSI = U1:D23, U5:CMD/SI;
net GND = U2:GND_TAB, U2:GROUND, GND:GND, U1 GND_1 - U3 8:GND, C3:P2, C2:P2, U2 GND_TAB - U2 ON/OFF:GND, U2:ON/OFF, J1:Terminal, C4:P2, U1:GND, U1:GND_1, U4:GND, U3:10, C1:P2, U5:GND, R1:P2, U3:8, LED1:K;
net VCC_3V3 = U4:VDD, LED1:A, C3:P1, U3:14, U1:3V3, C2:P1, U3:9, R1:P1, U5:3V, R2:P1, C1:P1;
net SD_CS = U1:D5, U5:D3/CS;
net ONE_WIRE = U1:D4, U4:DQ, R2:P2;
net SD_CLK = U5:CLK, U1:D18;
net VCC_5V = C4:P1, U2:FEEDBACK, U2:OUTPUT, U1:VIN;
net SCL = U3:11, U1:D22;
net SD_MISO = U5:DO/SO, U1:D19;
net SDA = U3:12, U1:D21;
}
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Files

Schematic

Layout

3D View

Schematic is Auto-placed

The schematic has been arranged automatically. Flux can redraw it to be more readable, with components placed in related groups and wires drawn more legibly. This takes about 10-60 mins.

Design Notes
Overview
ESP32-based predictive maintenance sensor node using an ESP32 DevKit C 30-pin module with CP2102, ADXL345 over I2C, DS18B20 over one-wire, and a Micro SD module over SPI.
Power Architecture
  • 9V DC input
  • LM2596 buck regulator configured for 5V output
  • 5V rail feeds ESP32 VIN
  • ESP32 onboard 3.3V rail feeds sensors and Micro SD module
Planned Net Names
  • VCC_5V
  • VCC_3V3
  • GND
  • SDA
  • SCL
  • ONE_WIRE
  • SD_CS
  • SD_CLK
  • SD_MISO
  • SD_MOSI
Planned GPIO Assignments
  • ADXL345 SDA -> GPIO21
  • ADXL345 SCL -> GPIO22
  • DS18B20 DATA -> GPIO4
  • Micro SD CS -> GPIO5
  • Micro SD CLK -> GPIO18
  • Micro SD MISO -> GPIO19
  • Micro SD MOSI -> GPIO23
Design Decisions
  • ADXL345 in I2C mode: CS tied to 3.3V, SDO tied to GND for address 0x53
  • Local 100nF decoupling capacitor added at each sensor/module VCC pin
  • 3.3V power LED with 330R series resistor
  • Functional grouping: Power, Microcontroller, Vibration Sensing, Temperature and Storage

  • Overview

  • Power Architecture

  • Planned Net Names

  • Planned GPIO Assignments

  • Design Decisions