TECHNICAL DATA

1

May 2014, Rev. 00

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 1-Wire, 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 read-out 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]

This command enables the bus master to read the 8-bit group code IZ1990, its

unique 48-bit serial number and 8-bit control total (CRC). This command can be used only,

if the bus has one device IZ1990. If the bus has more, than one slave, there will be a

conflict of data, when all slave ones, when all slave ones attempt to apply at the same time

IZ1990