DS2407

The DS2407 Dual Addressable Switch Plus Memory is a pair of open drain Nchannel transistors that can be turned on or off via the 1Wire bus. Alternatively, either open drain output can serve as a logic input that can be monitored via the same 1Wire bus. In addition, the device has 1024 bits of EPROM to store relevant information such as switch function, physical location, etc. The device is addressed by matching its individual 64bit factorylasered registration number. The 64bit number consists of an 8bit family code, a unique 48bit serial number, and an 8bit cyclic redundancy check.

Communication with the DS2407 follows the standard Dallas Semiconductor 1Wire protocol and can be accomplished with a single port pin of a microcontroller. Multiple DS2407 devices can reside on a common 1Wire bus creating a MicroLAN. The network controller circuitry is embedded within the chip including a search algorithm to determine the identity of each DS2407 on the network. The open drain outputs (PIO pins) for each DS2407 on the MicroLAN can be independently switched on or off whether there is one or many devices sharing the same 1Wire bus. The logic level of the PIO pins for each device on the MicroLAN can also be individually sensed and reported to the bus master. The device also supports a Conditional Search command to identify and access devices that qualify for certain userspecified conditions. Qualification may be the status of a PIOpin, the state of the output transistor or a latched activity flag.