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Troubleshooting

Quick fixes for the issues most readers run into while working through this section.

My ESP32-C3 won't connect to WiFi​

Check WiFi credentials and confirm the ESP32-C3 is on the same network as your computer. Two things specific to the C3:

  • The ESP32-C3 will not connect to 5 GHz WiFi networks. Use a 2.4 GHz network.

  • Use the WiFi power workaround in your sketch:

    WiFi.setTxPower(WIFI_POWER_8_5dBm);

    This sets the WiFi transmit power to 8.5 dBm and resolves connectivity issues specific to the C3.

See also: the WiFi sketch in Workshop 01: Arduino Setup which already includes this workaround.

My code won't upload to my ESP32 CYD​

Check, in order:

  1. Right board and port selected in Arduino IDE (Tools → Board → ESP32 → ESP32 Dev Module, then Tools → Port).
  2. CH340 driver installed. The CYD uses a CH340 USB-serial chip; the driver isn't installed by default on macOS or some Windows setups. See SparkFun's CH340 install guide.
  3. Different USB cable. Many cheap USB cables are charge-only - they don't have data lines. If your computer doesn't see the board, swap the cable.
  4. Lower the upload speed. Drop to 115200 baud in Tools → Upload Speed. Slower uploads are sometimes the only way to flash on flaky USB connections.

I'm having issues with I2C communication​

Most I2C problems boil down to one of:

  • Wrong SDA / SCL pins in your code (check your board's actual I2C pins - for the ESP32-C3 the defaults are GPIO 8 / GPIO 9).
  • Wrong I2C address for the device. Different sensors use different addresses (AHT10 = 0x38, SH1106 OLED = 0x3C or 0x3D).
  • Missing pull-up resistors on SDA / SCL. Most breakout boards include them; if yours doesn't, add 4.7 kΩ – 10 kΩ between each line and VCC.

If you don't know the I2C address of your device, run the I2C scanner sketch included in Workshop 03: Connect and Read Sensor Data - it enumerates every device responding on the bus.

My board is not detected by the Arduino IDE​

Check, in order:

  1. Right board selected (Tools → Board → ...).
  2. ESP32 board package installed (Tools → Board → Boards Manager → search "esp32" → install). See Arduino Setup for the full setup.
  3. CH340 driver installed if using the CYD. See SparkFun's CH340 install guide or the Adafruit CH9102 guide for similar chips.
  4. Different USB cable (data, not charge-only).

My serial monitor is not working or shows garbled text​

Two likely causes:

  • Baud rate mismatch. The serial monitor's baud rate (bottom-right of the IDE's Serial Monitor) must match Serial.begin(...) in your sketch. The workshops all use 115200.
  • Bad USB cable. Same as above - try a different one.

Adapted from the CardanoThings project, originally produced under Project Catalyst Fund 11. Source: github.com/CardanoThings.