DS18B20 Stainless Probe
A solution for coldchain monitoring using DS18B20 stainless temperature probes wired to an ESP32 gateway board.
The sensor
The classic sealed stainless temperature probe. Measures -55 to +125 °C at ±0.5 °C, submersible, and several probes can share one wire, so a single gateway watches every cold point on the property.
| Measures | Temperature only |
|---|---|
| Accuracy | ±0.5 °C between -10 °C and +85 °C |
| Accuracy, full range | ±2 °C across the whole -55 °C to +125 °C span |
| Measuring range | -55 °C to +125 °C; happy in any freezer |
| Resolution | 9 to 12 bits, your choice: 0.5 °C down to 0.0625 °C. Resolution is not accuracy |
| Conversion time | 93.75 ms at 9 bits, up to 750 ms at 12 bits |
| Address | A unique 64-bit code per probe, lasered in at the factory, so many can share one wire |
| Interface | 1-Wire: three wires (red power, black ground, yellow data), and every probe on the run shares them |
| Needs | One 4.7 k resistor between the data line and 3.3 V, for the whole bus. Without it there is no bus at all |
| How many per pin | No protocol limit; about eight to ten on a short run with the usual 4.7 k resistor |
| Probe | Sealed stainless tip on a waterproof cable; can sit submerged |
| Power | 3.3 V from the board; no batteries |
What you’ll need
1 × DS18B20 waterproof probe
The sealed stainless probe in the cold space; buy the multi-pack and one board can watch several coolers at once.
1 × An ESP32 board
Reads every probe on the wire and pushes each labeled reading to the endpoint you own.
1 × IP65 sealed project box
Keeps the board dry when it mounts somewhere damp or dusty.
How it works
Every DS18B20 carries its own factory-burned address and shares one data wire, so several probes chain along a single cable run. The gateway board reads each probe in turn and pushes every labeled reading to the endpoint you choose: your webhook, your MQTT broker, or the Test Bench.
One board, one wire, every cold point on the property. No batteries in the cold, no subscription.
Questions folks ask
How many probes can one board read?
Several. DS18B20 probes share a single data wire, each with its own factory-burned address, so one board can watch the walk-in, the reach-in, and the freezer with one cable run and label every reading.
Will it survive inside a freezer or under water?
Yes. The sealed stainless probe is rated -55 to +125 °C and can sit submerged in a tank or brine. The board stays outside in the dry.
Why choose it over the SHT-30 probe?
Price and reach: a few dollars per probe and easy multi-point runs. The trade is that it reads temperature only; if you also need humidity, that is the SHT-30's job.