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Sean Cardus edited this page May 17, 2026 · 1 revision

Probes Tab

The Probes tab manages the DS18B20 temperature probes wired to the controller. Each probe is auto-detected by its 1-Wire address; you then tell the device what each probe is (beer? ambient?) and which fermenter it belongs to.

OurBrewbot supports two DS18B20 buses:

  • Green Jack — Probe Bus 1 (GPIO0 / D3)
  • Black Jack — Probe Bus 2 (GPIO2 / D4)

You can mix probes across both buses; both are scanned and listed together.

Page Layout

The tab shows a single card containing a table of all detected probes, one row per probe:

Column Purpose
Address The 1-Wire ROM address of the probe (read-only). This is the device's unique ID and survives reboots.
Temp The probe's current reading. Shows -- in red if the probe is offline or returning a fault value.
Name A human-readable label for the probe (read-only here; auto-generated from index).
Function What the probe represents — Beer, Ambient, or Unassigned.
Fermenter Which fermenter (0 – 3, or None) this probe is wired to.
Adjust Per-probe temperature offset in °C, applied to every reading. Use for calibration against a reference thermometer.
Save Commits the row's changes.

If no probes are detected, the table shows a "No probes detected" message.

Configuring a Probe

For each probe row:

  1. Pick a Function:

    • Beer — the probe is in a thermowell, on the side of the fermenter, or otherwise reading wort temperature. The fermenter's heating/cooling state machine uses this reading.
    • Ambient — the probe is reading the air around the fermenter (e.g. inside the fridge). Logged for reference but does not drive control.
    • Unassigned — the probe is present but should be ignored.

  2. Pick a Fermenter the probe belongs to. None means the probe is read but not attached to any fermenter — useful for spare or in-test probes.

  3. Set a Temp Adjust (calibration offset). The reading shown to the rest of the system is raw + tempAdjust. To calibrate, put the probe in an ice bath and adjust until it reads 0 °C.

  4. Click Save on that row.

How Probes Drive Control

  • A fermenter's heating/cooling decisions use the Beer probe assigned to it. If multiple probes are assigned as Beer to the same fermenter, the first one wins.
  • A connected Tilt or iSpindel can also act as the Beer source — see the Tilts and iSpindels tabs. The probe is preferred unless one of those is configured to provide the beer temperature.
  • The Ambient probe is informational only and is exposed via the API, MQTT, and brew-service uploads.

Tips

  • Hot-plug new probes: add a probe at the jack and the next scan will pick it up. The new row appears with Function Unassigned and Fermenter None. Configure it and save.
  • Cold-side / hot-side plug control does not depend on probes here — control depends on whether a Beer probe (or Tilt / iSpindel acting as Beer) is providing a reading. Without one, the fermenter logs "no temperature reading" and forces both plugs off.
  • A probe showing -- in red usually means the probe has been disconnected or has failed. The 1-Wire address remains stored so reconnecting the same probe restores its assignment.
  • Probe Resolution is a global setting on the System Settings tab (9 – 12 bit). Higher resolutions are more precise but take longer per reading.

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