Troubleshooting

Solutions to common issues with RoastIQ.

ESP32 Won’t Flash

Symptom: Upload fails or hangs

Fix: Hold the BOOT button on the ESP32 while pressing EN (reset). Release BOOT after the upload starts.

Permission Denied on /dev/ttyUSB0

Symptom: “Permission denied” error when uploading or monitoring

Fix:

sudo usermod -aG dialout $USER
# Log out and back in for the group change to take effect

Artisan Shows “—” Instead of Temperatures

Symptom: Connected but no readings appear in Artisan

Causes and fixes:

  1. Thermocouple disconnected — Check serial monitor. If [TEMP] shows 0.0°C, the thermocouple may be loose. Verify connections at the MAX6675 screw terminals.

  2. Wrong network — Your computer must be connected to the ESP32’s network (either the RoastIQ WiFi access point or the same router network).

  3. Wrong IP address — Verify the WebSocket URL in Artisan matches the IP shown in the serial monitor.

WebSocket Connection Refused

Symptom: “Connection refused” error in Artisan

Fix:

  1. Verify the IP address in Artisan’s WebSocket URL
  2. Ensure no firewall is blocking port 80
  3. Try pinging the ESP32: ping 192.168.4.1
  4. Check serial output confirms the WebSocket server started

ESP32 Access Point Doesn’t Appear

Symptom: “RoastIQ” WiFi network not visible after flashing

Fix:

  1. Hold BOOT button and press EN (reset)
  2. Reflash with the dev environment (erases NVS): pio run -e dev --target upload

Temperature Shows 0.0°C

Symptom: Serial monitor shows BT: 0.0°C or ET: 0.0°C

Cause: MAX6675 not receiving power or thermocouple not connected

Fix:

  1. Check 3V3 and GND connections to the MAX6675
  2. Ensure the K-type thermocouple is firmly seated in the screw terminals (T+ and T-)
  3. Try a known-good thermocouple to rule out a broken probe

Temperature Shows 1023.75°C

Symptom: Serial monitor shows unrealistic high temperatures

Cause: Thermocouple is disconnected or the T+/T- wires are loose

Fix: Check the thermocouple connections at the MAX6675 screw terminals. If the probe is disconnected, the MAX6675 reports this sentinel value.

Temperature Jumps Erratically

Symptom: BT/ET values fluctuate wildly

Cause: Thermocouple may be cold, connections loose, or leads picking up electrical noise

Fix:

  1. This is normal for a cold thermocouple — values stabilize as the roaster heats up
  2. Check thermocouple connections at the MAX6675 screw terminals
  3. Route thermocouple leads away from mains wiring
  4. Ensure thermocouples are rated for the temperature range (K-type is good to ~1300°C)

WebSocket Disconnects Frequently

Symptom: Artisan loses connection to the ESP32

Fix:

  1. Reduce the number of WebSocket clients (close other browser tabs connected to the ESP32)
  2. Check pio device monitor for [HEAP] warnings — low memory can cause instability
  3. Restart the ESP32 by pressing the EN (reset) button

Further Help