The regional government of Andalusia, Spain, has a very strict regulation for monitoring the temperatures in refrigerators and refrigeration chambers for certain hospitality businesses. This regulation mandates daily logging of lowest and highest temperatures for every refrigerator at restaurants and other businesses serving food.

Even though the logging can be performed manually, this is a hassle for businesses owning a large number of refrigerators. To solve this problem I designed a wireless sensor probe for the company Plantecnic, in Spain. These probes connect via WiFi to the network and allow Plantecnic’s software to retrieve temperatures from all refrigerators at the venue in real time, fully automating the task and providing alarms when temperatures go out of range.

First model

To build the probes, I developed firmware running on an Espressif ESP32 and the case housing the electronics. These probes are integrated into Plan7 software and they use the existing WiFi infrastructure at the final user’s premises.

Logging software

Later, the probe was upgraded using a ready-to-go M5StickC. Software had to be ported to the new device.

Newer model

At the time of writing, there are tens of these probes deployed at different customers’ premises.

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