21
Maxim Integrated
DS2483
Single-Channel 1-Wire Master
with Adjustable Timing and Sleep Mode
Not Acknowledged by Slave: A slave device could
be unable to receive or transmit data, e.g., because
it is busy performing a real-time function or is in
sleep mode. In this case, the slave device does not
acknowledge its slave address and leaves the SDA
line high. A slave device that is ready to communicate
acknowledges at least its slave address. However,
some time later the slave can refuse to accept data,
e.g., because of an invalid command 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 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 DS2483
To write to the DS2483, 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 DS2483
acknowledges valid command codes and expected/
valid command parameters. Additional bytes or invalid
command parameters are never acknowledged.
Reading from the DS2483
To read from the DS2483, 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
mand and then access the DS2483 again in read mode.
I2C Communication Examples
legend and data direction codes.
Table 10. I2C Communication—Legend
Table 11. Data Direction Codes
SYMBOL
DESCRIPTION
S
START Condition
AD, 0
Select DS2483 for Write Access
AD, 1
Select DS2483 for Read Access
Sr
Repeated START Condition
P
STOP Condition
A
Acknowledged
A\
Not Acknowledged
(Idle)
Bus Not Busy
<byte>
Transfer of One Byte
DRST
Command “Device Reset” (F0h)
SRP
Command “Set Read Pointer” (E1h)
WCFG
Command “Write Device Configuration” (D2h)
ADJP
Command “Adjust 1-Wire Port” C3h)
1WRS
Command “1-Wire Reset” (B4h)
1WSB
Command “1-Wire Single Bit” (87h)
1WWB
Command “1-Wire Write Byte” (A5h)
1WRB
Command “1-Wire Read Byte” (96h)
1WT
Command “1-Wire Triplet” (78h)
Master-to-Slave Slave-to-Master