Datasheet

DS1904
3 of 13
HIERARCHICAL STRUCTURE FOR 1-WIRE PROTOCOL F
igure 2
DS1904
Command
Level
Available
Commands
Data Fields
Affected
1-Wire Bus
Other
Devices
Bus
Master
DS1904 specific
Function Commands
(see Figure 5)
Write Clock
Read Clock
RTC Counter, Device Control
RTC Counter, Device Control
Read ROM
Match ROM
Search ROM
Skip ROM
64-bit ROM
64-bit ROM
64-bit ROM
N/A
1-Wire ROM Function
Commands (see Figure 7)
64-BIT LASERED ROM F
igure 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