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, wire length, and noise tolerance. A typical limit is around 10-20 devices.
To ensure accurate temperature readings, make sure to follow proper PCB layout and thermal design guidelines, use a high-quality 1-Wire bus implementation, and perform temperature calibration during manufacturing or in the application software.
Yes, the DS1821 supports multi-drop configuration, where multiple devices can be connected to the same 1-Wire bus. Each device has a unique 64-bit ROM code, allowing the master device to address and communicate with individual DS1821 devices.
The VDD pin is used to power the internal logic and EEPROM of the DS1821. It should be connected to a stable voltage source between 3.0V and 5.5V. Note that the DS1821 can operate in a parasitic power mode, where the VDD pin is not connected, but this mode has limitations and is not recommended for most applications.
The 1-Wire bus reset signal is used to initialize the bus and ensure that all devices are in a known state. The master device should generate a reset pulse of at least 480μs to reset the bus. The DS1821 will respond with a presence pulse after the reset signal.
