Theoretically, up to 256 devices can be connected to a single 1-Wire bus, but in practice, the maximum number is limited by the bus capacitance and the quality of the wiring. A good rule of thumb is to limit the number of devices to 10-20 per bus.
To ensure accurate temperature readings, make sure to follow proper wiring and layout guidelines, use a high-quality 1-Wire bus, and avoid electromagnetic interference (EMI). Also, perform a parasite power supply configuration to reduce power consumption and noise.
The VDD pin is used to provide power to the internal circuitry of the DS18B20. It is not necessary to connect VDD to a power source if the device is powered parasitically through the 1-Wire bus. However, if the device is not powered parasitically, VDD must be connected to a 3.0V to 5.5V power source.
The 1-Wire bus reset signal is used to reset the bus and all devices connected to it. The reset signal is a low pulse of at least 480μs duration. The DS18B20 will respond to the reset signal by entering a low-power state and releasing the bus.
The DS18B20 and DS18S20 are both digital temperature sensors from Maxim Integrated Products. The main difference between them is the package type: the DS18B20 is available in a 3-pin TO-92 package, while the DS18S20 is available in a 6-pin SOT-23 package. The DS18S20 also has a slightly higher accuracy specification.
