
DS1922E
iButton High-Temperature Logger with
8KB Data-Log Memory
BUS
MASTER
1-Wire NET
OTHER DEVICES
DS1922E
COMMAND LEVEL:
1-Wire ROM
FUNCTION COMMANDS
DS1922E-SPECIFIC
AVAILABLE COMMANDS:
READ ROM
MATCH ROM
SEARCH ROM
CONDITIONAL SEARCH ROM
SKIP ROM
RESUME
OVERDRIVE-SKIP ROM
OVERDRIVE-MATCH ROM
WRITE SCRATCHPAD
READ SCRATCHPAD
COPY SCRATCHPAD WITH PW
READ MEMORY WITH PW AND CRC
CLEAR MEMORY WITH PW
DATA FIELD AFFECTED:
64-BIT ROM, RC-FLAG
64-BIT ROM, RC-FLAG
64-BIT ROM, RC-FLAG
64-BIT ROM, RC-FLAG, ALARM FLAGS, SEARCH CONDITIONS
RC-FLAG
RC-FLAG
RC-FLAG, OD-FLAG
64-BIT ROM, RC-FLAG, OD-FLAG
256-BIT SCRATCHPAD, FLAGS
256-BIT SCRATCHPAD
512-BYTE DATA MEMORY, REGISTERS, FLAGS, PASSWORDS
MEMORY, REGISTERS, PASSWORDS
MISSION TIMESTAMP, MISSION SAMPLES COUNTER,
MEMORY FUNCTION COMMANDS
FORCED CONVERSION
START MISSION WITH PW
STOP MISSION WITH PW
Figure 2. Hierarchical Structure for 1-Wire Protocol
MSB
START DELAY, ALARM FLAGS, PASSWORDS
MEMORY ADDRESSES 020Ch TO 020Dh
FLAGS, TIMESTAMP, MEMORY ADDRESSES
020Ch TO 020Dh (WHEN LOGGING)
FLAGS
LSB
8-BIT
CRC CODE
48-BIT SERIAL NUMBER
8-BIT FAMILY CODE
(41h)
MSB
LSB MSB
LSB MSB
LSB
Figure 3. 64-Bit Lasered ROM
POLYNOMIAL = X 8 + X 5 + X 4 + 1
1ST
STAGE
2ND
STAGE
3RD
STAGE
4TH
STAGE
5TH
STAGE
6TH
STAGE
7TH
STAGE
8TH
STAGE
X 0
X 1
X 2
X 3
X 4
X 5
X 6
X 7
X 8
INPUT DATA
Figure 4. 1-Wire CRC Generator
8
Maxim Integrated