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Why is the temperature sensor DS18B20 not detected?
Under version 8.1.0.7 both sensors were detected and worked fine. However, after building and uploading 8.1.0.10 the DS18B20 is detected and works fine on one module but is not detected at all on the other module. I think this reduces the chance of it being related to the compiler.
Can a DS18B20 be used in normal mode?
The DS18B20 can work in a regular mode or in a so called Parasite mode. The normal mode requires 3 wires, whereas the Parasite mode uses only 2 wires. Make sure you set the right data pin! In line 10, where it says “ OneWire ds (2); ” the data pin to be used is set.
Where does the data go on an Arduino DS18B20?
The wiring, this is the beauty of a 1-wire interface, is super simple. The GND pin of the DS18B20 goes to GND on the Arduino. The Vdd pin of the DS18B20 goes to +5V on the Arduino. The Data pin of the DS18B20 goes to a (digital) pin of your choice on the Arduino, in this example I used Pin 2.
What’s the difference between parasite and VDD on DS18B20?
The alternative wiring is called “Parasite” mode, where we do NOT connect the +5V to the Vdd pin of the DS18B20. Instead we connect Vdd of the DS18B20 to GND. The advantage being obvious: you only need 2 wires. The downside of parasite mode is that you should limit the number of sensors and the wires should not be too long!
What do you need to know about DS18B20?
DS18B20 needs strong pull-up on the data line in this mode achievable by issuing this commands: parasitic power mode features simplicity in wiring. Only 2 wires needed for this mode. This is especially important when one want to wire a big number of sensors together.
Can a DS18B20 be used in parasite power mode?
You can use DS18B20 in parasite power mode, meaning that you only need two wires: ground and data, no need for pullup resistor for the data. As per the datasheet ( http://datasheets.maximintegrated.com/en/ds/DS18B20.pdf page 2): VDD must be grounded for operation in parasite power mode.
Why is the temperature sensor on my NodeMCU not detected?
I am using several NodeMCU V3 boards, and I have noticed that very frequently (under unknown circumstances) the temperature sensor (DS18B20) is not detected at all, although it is correctly connected (D2 GPIO04, pull-up resistor 4.7k), and the software is configured: Module type: Generic (18), and D2 GPIO4 with DS18x20 (4)