Building a Cold-Chain Monitor with the DS18B20 Stainless Probe
The DS18B20 is a sealed stainless probe that measures temperature over three wires, a connection called 1-Wire that lets several probes share one cable. It wires straight to the ESP32, which sends measurements to an endpoint for use.
1 · The parts
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.
2 · Load the program
“Flashing” means loading the program onto the board, the way you would install an app on a phone. The program for this build is on the bench now. When it lands, this step gets its Flash the ESP32 button like every live build; the parts and wiring above will not change.
Program Coming Soon The Software Library
3 · Wire and place it
Three wires: power, ground, and data, with one 4.7 kΩ resistor between data and power for the whole wire. Every probe joins the same three conductors, so adding the freezer to the run is a splice, not a new cable.
The sealed stainless probes live in the cold (or in the tank; they can sit submerged). The board stays outside in the dry, on USB power, in the sealed box if its spot is damp.
4 · Choose where readings go
During setup the board asks for one address: where every reading should land. That is your webhook or MQTT broker. If you do not have one yet, use the Test Bench. Enter it in the program’s Set It Up section along with your Wi-Fi; its Push Now check tells you readings are landing.