Rainbow Electronics DS1904 - Manual (Page 3)

DS1904
3 of 12
HIERARCHICAL STRUCTURE FOR 1-WIRE PROTOCOL Figure 2
DS1904
Command
Level Available
Commands Data Fields
Affected
1-Wire Bus
Other
Devices
Bus
Master
DS1904
Function
(see Figure
Write
Read RTC Counter, Device
RTC Counter, Device
Read
Match
Search
Skip 64-bit
64-bit
64-bit
N/A
1-Wire ROM
Commands (see Figure
64-BIT LASERED ROM Figure 3
MSB LSB
8-Bit CRC Code 48-Bit Serial Number 8-Bit Family Code (24h)
MSB LSB MSB LSB MSB LSB
1-WIRE CRC GENERATOR Figure 4
R
X 2 X 1 X 0 X 8 X 7 X 6 X 5 X 4 X 3
8TH
STAGE
7TH
STAGE
6TH
STAGE
5TH
STAGE
4TH
STAGE
3RD
STAGE
2ND
STAGE
1ST
STAGE
S
INPUT DATA
Polynomial = X 8 + X 5 + X 4 + 1