PCB Schematic Design for ESP32 IoT Sensor

flux

0:45

Troubleshooting project errors.

Analyzing the schematic.

Running design review.

Analyzing the PCB layout.

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

What they are

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.
19 days
hannahnabill310

hannahnabill310

Fix the U1 VP ERC warning.
19 days

flux

0:38

Running design review.

Analyzing the schematic.

Running design review.

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
19 days

Applied changes.

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;

}

19 days
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U1
U1 D5 - U5 D3/CS
U1 D21 - U3 12
U2 OUTPUT - U1 VIN
U1 D22 - U3 11
U1 D23 - U5 CMD/SI
U1 D4 - U4 DQ
U1 D18 - U5 CLK
U1 D19 - U5 DO/SO
U1 3V3 - U3 14
U2 GND_TAB - U2 ~ON~/OFF
U1 GND_1 - U3 8
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