DS18B20 1-Wire temperature probe to the cloud with an ESP32

Analog Devices (Maxim)·Environment sensors·1-WireDatasheet-derived

The classic waterproof stainless temperature probe, read over a single data wire by the gateway's 1-Wire driver. Good for tanks, pipes and enclosures from −55 to +125 °C.

The Synacl ESP32 gateway reads the DS18B20 1-Wire temperature probe over 1-Wire. This catalog entry carries the register map, scaling and connection defaults below, so adding it in the app is a pick from a list rather than a form filled in from the datasheet — and it is the same data an AI agent gets from the list_catalog MCP tool.

Registers · 1 tag

Engineering value = raw × scale + offset; the gateway sends the raw reading and Synacl scales it.

Connection defaults

Wiring

Data (yellow) to GPIO 4 (the gateway default) with a 4.7 kΩ pull-up between data and 3.3 V; VCC (red) to 3.3 V; GND (black) to GND. Several probes can share the same pin.

Notes

• The gateway reads probes in bus order: temperature_probe_1 is the first probe found; add temperature_probe_2 and _3 tags for more probes on the same pin.
• Wire colours vary by batch — confirm with the probe's own label rather than trusting red/yellow/black.
• Datasheet-derived (the driver is the DallasTemperature library on the gateway); not yet bench-verified on this platform. If a reading does not match, report the mismatch.

Set it up in three steps

1. Flash the gateway from the browser
   Plug an ESP32 dev board into USB, open the free web flasher in Chrome or Edge and write the Synacl gateway firmware. It asks for Wi-Fi and pairs the gateway with your account — nothing to install, about two minutes.
2. Add the DS18B20 1-Wire temperature probe from the catalog
   In the app open Devices → Add device and choose “Start from a catalog device”, then pick DS18B20 1-Wire temperature probe. The 1-Wire settings and every tag in the table above are filled in; choose the gateway it is wired to, change the pin if yours differs, and save. How the catalog picker works →
3. Watch the live data arrive
   The gateway receives the new configuration over MQTT within seconds and starts polling. Readings show on the device page and in any dashboard widget you bind to them; add a rule for alerts, keep history for reports, or let an AI agent read it over MCP.

How this entry was verified

Datasheet-derived — derived from the vendor datasheet and not yet confirmed on hardware — please report a mismatch.

Bench-verified means Synacl ran this entry on real hardware. Datasheet-derived means the map was transcribed from the vendor's documentation, so a register may be off by one or in the other word order on your unit — a two-line email fixes it for everyone.

Report a register mismatch · Vendor datasheet ↗ · All catalog devices