DS9101 datasheet(13/55 Pages) MAXIM

13 / 55 page

Hygrochron Temperature/Humidity Logger

iButton with 8KB Data-Log Memory

______________________________________________________________________________________

AVAILABLE COMMANDS:

DATA FIELD AFFECTED:

READ ROM

MATCH ROM

SEARCH ROM

CONDITIONAL SEARCH ROM

SKIP ROM

RESUME

OVERDRIVE-SKIP ROM

OVERDRIVE-MATCH ROM

64-BIT ROM, RC-FLAG

64-BIT ROM, RC-FLAG, ALARM FLAGS, SEARCH CONDITIONS

RC-FLAG

RC-FLAG, OD-FLAG

64-BIT ROM, RC-FLAG, OD-FLAG

1-Wire ROM

FUNCTION COMMANDS

WRITE SCRATCHPAD

READ SCRATCHPAD

COPY SCRATCHPAD WITH PW

READ MEMORY WITH PW AND CRC

CLEAR MEMORY WITH PW

FORCED CONVERSION

START MISSION WITH PW

STOP MISSION WITH PW

256-BIT SCRATCHPAD, FLAGS

256-BIT SCRATCHPAD

512-BYTE DATA MEMORY, REGISTERS, FLAGS, PASSWORDS

MEMORY, REGISTERS, PASSWORDS

MISSION TIMESTAMP, MISSION SAMPLES COUNTER,

START DELAY, ALARM FLAGS, PASSWORDS

MEMORY ADDRESSES 020Ch TO 020Fh

FLAGS, TIMESTAMP, MEMORY ADDRESSES

020Ch TO 020Fh (WHEN LOGGING)

FLAGS

DS1923-SPECIFIC

MEMORY/CONTROL FUNCTION

COMMANDS

COMMAND LEVEL:

BUS

MASTER

1-Wire NET

OTHER DEVICES

DS1923

Figure 2. Hierarchical Structure for 1-Wire Protocol

MSB

8-BIT

CRC CODE

48-BIT SERIAL NUMBER

MSB

LSB

8-BIT FAMILY CODE

(41h)

MSB

LSB

Figure 3. 64-Bit Lasered ROM

64-Bit Lasered ROM

Each DS1923 contains a unique ROM code that is 64

bits long. The first 8 bits are a 1-Wire family code. The

next 48 bits are a unique serial number. The last 8 bits

are a cyclic redundancy check (CRC) of the first 56 bits

(see Figure 3 for details). The 1-Wire CRC is generated

using a polynomial generator consisting of a shift regis-

ter and XOR gates as shown in Figure 4. The polynomi-

al is X8 + X5 + X4 + 1. Additional information about the

1-Wire CRC is available in Application Note 27:

Understanding and Using Cyclic Redundancy Checks

with Maxim iButton Products.

The shift register bits are initialized to 0. Then, starting

with the least significant bit of the family code, one bit

at a time is shifted in. After the 8th bit of the family code

has been entered, the serial number is entered. After

the last bit of the serial number has been entered, the

shift register contains the CRC value. Shifting in the 8

bits of CRC returns the shift register to all 0s.

DS9101 Datasheet(PDF) 13 Page - Maxim Integrated Products

DS9101 Datasheet(HTML) 13 Page - Maxim Integrated Products

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