DS2409 Dallas Semiconducotr, DS2409 Datasheet - Page 3

• Manufacturer Part Number: DS2409
• Description: MicroLAN Coupler
• Manufacturer: Dallas Semiconducotr

64-BIT LASERED ROM
Each DS2409 contains a unique ROM code that is 64 bits long. The first eight bits are a 1-Wire family
code. The next 48 bits are a unique serial number. The last eight bits are a CRC of the first 56 bits. (See
Figure 3.) The 1-Wire CRC of the lasered ROM is generated using the polynomial X
Additional information about the Dallas Semiconductor 1-Wire Cyclic Redundancy Check is available in
the Book of DS19xx iButton Standards. The 64-bit ROM and ROM Function Control section allow the
DS2409 to operate as a 1-Wire device and follow the 1-Wire protocol detailed in the section “1-Wire Bus
System”. The functions required to exercise the control functions of the DS2409 are not accessible until
the ROM function protocol has been satisfied. This protocol is described in the ROM functions flow
chart (Figure 7). The 1-Wire bus master must first provide one of the five ROM function commands.
After a ROM function sequence has been successfully executed, the bus master may then provide any one
of the function commands specific to the DS2409 (Figure 5).
HIERARCHICAL STRUCTURE FOR 1-WIRE PROTOCOL Figure 2
64-BIT LASERED ROM Figure 3
MSB
MSB
8-Bit CRC Code
LSB MSB
48-Bit Serial Number
3 of 18
LSB MSB
8-Bit Family Code (1FH)
8
+ X
5
+ X
102199
DS2409
4
LSB
LSB
+ 1.