Datasheet

DS2482-100: Single-Channel 1-Wire Master
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1-Wire Read Byte
Command Code
96h
Command Parameter
None
Description
Generates eight read-data time slots on the 1-Wire line and stores result
in the Read Data register.
Typical Use
To read data from the 1-Wire line; equivalent to executing eight 1-Wire
Single Bit commands with V = 1 (write-1 time slot), but faster due to less
I
2
C traffic.
Restriction
1-Wire activity must have ended before the DS2482-100 can process this
command.
Error Response
Command code is not acknowledged if 1WB = 1 at the time the command
code is received and the command is ignored.
Command Duration
8 × t
SLOT
+ maximum 262.5ns, counted from the falling SCL edge of the
command code acknowledge bit.
1-Wire Activity
Begins maximum 262.5ns after the falling SCL edge of the command
code acknowledge bit.
Read Pointer Position
Status register (for busy polling)
NOTE: To read the data byte received from the 1-Wire line, issue the Set
Read Pointer command and select the Read Data register. Then access
the DS2482-100 in read mode.
Status Bits Affected
1WB (set to 1 for 8 × t
SLOT
)
Configuration Bits Affected
1WS, APU apply
1-Wire Triplet
Command Code
78h
Command Parameter
Direction Byte
Description
Generates three time slots, two read time slots, and one write time slot at
the 1-Wire line. The type of write time slot depends on the result of the
read time slots and the direction byte.
The direction byte determines the type of write time slot if both read time
slots are 0 (a typical case). In this case the DS2482-100 generates a write
1-time slot if V = 1 and a write-0 time slot if V = 0.
If the read time slots are 0 and 1, there follows a write-0 time slot.
If the read time slots are 1 and 0, there follows a write-1 time slot.
If the read time slots are both 1 (error case), the subsequent write time
slot is a write 1.
Typical Use
To perform a 1-Wire Search ROM sequence; a full sequence requires this
command to be executed 64 times to identify and address one device.
Restriction
1-Wire activity must have ended before the DS2482-100 can process this
command.
Error Response
Command code and direction byte is not acknowledged if 1WB = 1 at the
time the command code is received and the command will be ignored.
Command Duration
3 × t
SLOT
+ maximum 262.5ns, counted from the falling SCL edge of the
first bit (MS bit) of the direction byte.
1-Wire Activity
Begins maximum 262.5ns after the falling SCL edge of the MS bit of the
direction byte.
Read Pointer Position
Status register (for busy polling)
Status Bits Affected
1WB (set to 1 for 3 × t
SLOT
)
SBR is updated at the first t
MSR
TSB and DIR are updated at the second t
MSR
(i. e., at t
SLOT
+ t
MSR
)
Configuration Bits Affected
1WS, APU apply
Bit Allocation in the Direction Byte
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
V x x x x x x x x = don’t care