DS2465 MAXIM [Maxim Integrated Products], DS2465 Datasheet - Page 24

• Manufacturer Part Number: DS2465
• Description: SHA-256 Coprocessor with 1-Wire Master Function
• Manufacturer: MAXIM [Maxim Integrated Products]

To write to the DS2465, the master must access the
device in write access mode, i.e., the slave address must
be sent with the direction bit set to 0. The next byte to be
sent in write access mode is an address byte to select
the register or memory address to be written to or to
set the address for a subsequent read access (dummy
write).
To read from the DS2465, the master must access the
device in read access mode, i.e., the slave address must
Figure 11. Address-Specific Read and Write Behavior
SHA-256 Coprocessor with 1-Wire Master Function
slave may refuse to accept data, possibly because of
an invalid command code or unexpected data. 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 mas-
ter 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. 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.
ADDRESS
00h to 4Bh
4Ch to 5Fh
67h to 6Dh
80h to BFh
C0h to FFh
6Eh to 6Fh
70h to 73h
74h to 7Fh
RANGE
60h
61h
62h
66h
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ACCESS
(R)/(W)
R/W
R/W
—
—
—
—
—
W
R
R
R
READ/WRITE
BEHAVIOR
Read and Write
Type 1
Type 1
Type 2
Type 3
Type 4
Type 1
Type 1
Type 1
Type 4
Type 4
Type 4
Type 4
Refer to the full data sheet.
Scratchpad.
Reserved. Data written is not stored. Data read is indeterminate.
Command register.
1-Wire Master Status.
1-Wire Read Data.
Reserved
1-Wire Configuration.
Reserved. Data written is not stored. Data read is indeterminate.
Factory-programmed data.
Reserved. Data read is indeterminate.
User memory.
Reserved. Data written is not stored. Data read is indeterminate.
be sent with the direction bit set to 1. The read address
is determined either from a preceding write access or
implied from a function command.
The DS2465 has different types of memory. Some areas
allow unrestricted read/write access [R/W], others are
write-only [W], read-only [R] or have user-programmable
access restrictions [(R)/(W)].
consequence, the read and write behavior is address
dependent.
The common I
data acknowledge and address auto-increment applies.
This behavior applies to the command register, the
address to which commands and parameter bytes are
written, e.g., to activate the SHA engine or to start any
activity on the 1-Wire port. When accessed in write mode,
the address does not increment. The subsequent read
position is implied by the command code that the mas-
ter writes. When accessed in read mode coming from a
lower address, the data read is indeterminate, but the
address increments.
Figure 11
2
NOTES
C random access read/write protocol with
shows details.
DS2465
Type 1 Behavior
Type 2 Behavior
As a