Fault Isolating Temperature Sensor Network Controller
Arduino temperature sensor controller turns off individual units to help diagnose faults.
A few years ago, creator mmithril set up a DS18B20 temperature network for a Raspberry Pi-based greenhouse heating controller. Unfortunately, the reliability of the setup was poor due to frequent sensor outages. Reliability was especially bad during the winter when heat was actually needed, while the system experienced almost no problems during the summer months.
To help fix this problem, mmithril built a dedicated Arduino sensor controller, which is able to cycle each sensor on and off one by one. The system is configured with a header setup for the sensor's 1-wire bus, enabling each to plug in there for data transfer. Sensors also connect to digital pins acting as the +5V and GND inputs. Since the DS18B20 sensor only consumes up to 1.5mA when in use, this is well within the Arduino’s 40mA capacity, allowing for each sensor to be turned on, or completely shut off by tri-stating the pins as inputs
It’s a clever project, and a good reminder that you can use an Arduino’s digital IO for power supply in limited circumstances. In this case, it let mmithril determine that the sensor failure was likely due to the high capacitance of the longer wiring, and that one sensor is likely broken. Sometimes fixing a problem is an interesting pursuit in itself!