IZ1990

IZ1990 CMOS IC FOR ELECTRONIC KEY DESCRIPTION CMOS microcircuit is essentially an electronic carrier of the unique 64-bit digital code. The code is stored in the internal nonvolatile memory. The data exchange is performed by the protocol 1Wire, which requires one sole data pin and the common pin. The microcircuit supports the function of the protocol 1-Wire of ROM search, which makes it possible for several devices to operate on one bus. This protocol determines the alteration conditions of the bus status and the time intervals during synchronization by the synchropulses cuts of the control device. Data readout and writing are performed by the junior significant bit forward. TRANSACTION SEQUENCE Access sequence to IZ1990 via 1-Wire port is as follows: Initialization ROM function command Data read-out INITIALIZATION All transactions on the bus 1-Wire start with the initialization sequence. The initialization sequence consists of the reset pulse, applied by the bus master, followed by the availability pulse (or pulses), applied by the slave buses (or slave buses). The availability pulse informs the bus master, that IZ1990 is connected to the bus and is ready for operation. ROM FUNCTIONS COMMANDS After the bus master has determined availability of the device, it can apply one out of four commands for operation with ROM. All commands for operation with ROM have the length of 8 bits. These commands are enumerated below (see also the diagram in Fig. 4) ROM Reading [33h] or [0Fh]...