Troubleshooting

Work through these before asking for help.

Sensor Reads 0 or a Fixed Value

Check your wiring — is the sensor connected to the correct pin?
Check the pin number in your sketch matches your wiring
Open the Serial Monitor and print the raw value — is it changing at all?
For analog sensors: make sure you are using an ADC-capable pin (on ESP32: GPIO 32–39)
For I2C sensors: check the I2C address in your sketch matches the sensor (use an I2C scanner sketch to confirm)

Check the baud rate in the Serial Monitor matches Serial.begin() in your sketch (should be 115200)
Make sure you selected the correct port: Tools → Port
Try unplugging and replugging the USB cable
If using CodeCell or a clone board, you may need to install a USB driver (CP2102 or CH340)

Double-check your SSID and password in the sketch — they are case-sensitive
Make sure your phone hotspot is on and visible
Do not use eduroam — it blocks device-to-device communication
After uploading, open the Serial Monitor to see the connection status — it will print the assigned IP address when connected

Confirm your laptop’s IP address on the hotspot: System Settings → Network → Wi-Fi → Details
Check that the IP in your sketch matches your laptop’s current IP — it changes each time you reconnect
Check that the port number in your sketch matches the port in your Max/Plugdata patch (default: 9000)
Make sure your laptop and ESP32 are on the same network (the same hotspot)
The Serial Monitor and Max/Plugdata cannot read the same serial port simultaneously — close one before opening the other

Increase the SMOOTHING value in the Starter Sketch (e.g. from 0.1 to 0.05 for more smoothing)
Check your wiring for loose connections
For capacitive sensors: keep wires short and away from power lines
For analog sensors: add a small capacitor between signal and GND to filter noise

If Wi-Fi drops, fall back to USB serial — see Serial Monitor
Make sure your power bank has enough capacity — the ESP32 draws more current when transmitting Wi-Fi
Build reconnection logic into your sketch so the ESP32 reconnects automatically if Wi-Fi drops