DS2482-100 Dallas Semiconducotr, DS2482-100 Datasheet - Page 16

• Manufacturer Part Number: DS2482-100
• Description: Single-Channel 1-Wire Master
• Manufacturer: Dallas Semiconducotr

A slave device that is ready to communicate will acknowledge at least its slave address. However, some time later
the slave may refuse to accept data, e.g., 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 needs to generate 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
To write to the DS2482, 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 acknowledges valid command codes and expected/valid
command parameters. Additional bytes or invalid command parameters are never acknowledged.
Reading from the DS2482
To read from the DS2482, 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 will read from. The master
may continue reading the same register over and over again, without having to re-address 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 again in read mode.
I²C Communication—Legend
Data Direction Codes
SYMBOL
Master-to-Slave
<byte>
AD, 0
AD, 1
(Idle)
Sr
A\
S
P
A
START Condition
Select DS2482 for Write Access
Select DS2482 for Read Access
Repeated START Condition
STOP Condition
Acknowledged
Not Acknowledged
Bus Not Busy
Transfer of One Byte
Slave-to-Master
DESCRIPTION
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SYMBOL
1WWB
WCFG
1WRS
1WRB
1WSB
DRST
1WT
SRP
Command "Device Reset", F0h
Command "Write Configuration", D2h
Command "Set Read Pointer", E1h
Command "1-Wire Reset", B4h
Command "1-Wire Write Byte", A5h
Command "1-Wire Read Byte", 96h
Command "1-Wire Single Bit", 87h
Command "1-Wire Triplet", 78h
DESCRIPTION