DS2482-100_15 Datasheet, PDF (17/24 Pages) Maxim Integrated Products – Single-Channel 1-Wire Master

DS2482-100
Single-Channel 1-Wire Master
some time later the slave may refuse to accept data,
possibly because of an invalid command code or
parameter. In this case, the slave device does not
acknowledge any of the bytes that it refuses and
leaves SDA high. In either case, after a slave has
failed to acknowledge, the master first should gener-
ate a repeated START condition or a STOP condition
followed by a START condition to begin a new data
transfer.
Not Acknowledged by Master: At some time when
receiving data, the master must signal an end of
data to the slave device. To achieve this, the master
does not acknowledge the last byte that it has
received from the slave. In response, the slave
releases SDA, allowing the master to generate the
STOP condition.
Writing to the DS2482-100
To write to the DS2482-100, the master must access
the device in write mode, i.e., the slave address must
be sent with the direction bit set to 0. The next byte to
be sent is a command code, which, depending on the
command, may be followed by a command parameter.
The DS2482-100 acknowledges valid command codes
and expected/valid command parameters. Additional
bytes or invalid command parameters are never
acknowledged.
Reading from the DS2482-100
To read from the DS2482-100, the master must access
the device in read mode, i.e., the slave address must
be sent with the direction bit set to 1. The read pointer
determines the register that the master reads from. The
master can continue reading the same register over
and over again, without having to readdress the device,
e.g., to watch the 1WB changing from 1 to 0. To read
from a different register, the master must issue the Set
Read Pointer command and then access the DS2482-
100 again in read mode.
I²C Communication Example
See Tables 4 and 5 for the I²C communication legend
and data direction codes.
Table 4. I²C Communication—Legend
SYMBOL
S
AD, 0
AD, 1
Sr
P
A
A\
(Idle)
<byte>
DRST
SRP
WCFG
1WRS
1WSB
1WWB
1WRB
1WT
DESCRIPTION
START Condition
Select DS2482-100 for Write Access
Select DS2482-100 for Read Access
Repeated START Condition
STOP Condition
Ac know ledged
Not Acknowledged
Bus Not Busy
Transfer of One Byte
Command “Device Reset”, F0h
Command “Set Read Pointer”, E1h
Command “Write Configuration”, D2h
Command “1-Wire Reset”, B4h
Command “1-Wire Single Bit”, 87h
Command “1-Wire Write Byte”, A5h
Command “1-Wire Read Byte”, 96h
Command “1-Wire Triplet”, 78h
Table 5. Data Direction Codes
Master-to-Slave Slave-to-Master
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