ElectronicZoologyfield notes from the garage
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Charge Only Won't flash Data Cable Flashes fine
Common Gotcha

USB Cable

Not all cables work for flashing

USB cables look identical from the outside but are not all the same inside. Charge-only cables contain just the power wires (VBUS and GND) - they will power your ESP32 but the computer will never see it, so you cannot upload a sketch.

Data cables contain all four wires including D+ and D- which carry the serial communication needed for flashing. If your ESP32 powers up but does not appear in the Arduino IDE port list, swap the cable first - it is the most common cause and takes 10 seconds to rule out.

Key details

  • Charge-only cables: power only, no data - will not flash
  • Data cables: all 4 wires - required for flashing
  • ESP32 powers on either way - the LED is no proof
  • If port does not appear in IDE: swap cable first