DS1876 datasheet(24/69 Pages) MAXIM

24 / 69 page

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SFP Controller with Dual LDD Interface

The register maps show each byte/word (2 bytes) in

terms of its row in the memory. The first byte in the row

is located in memory at the row address (hexadecimal)

in the leftmost column. Each subsequent byte on the row

is one/two memory locations beyond the previous byte/

word’s address. A total of 8 bytes are present on each

row. For more information about each of these bytes, see

the corresponding register description.

Memory Map Access Codes

The following section provides the DS1876 register defi-

nitions. Each register or row of registers has an access

descriptor that determines the password level required

to read or write the memory. Level 2 password is

intended for the module manufacture access only. Level

1 password allows another level of protection for items

the end consumer wishes to protect. Many registers are

always readable, but require password access to write.

There are a few registers that cannot be read without

password access. The following access codes describe

each mode used by the DS1876 with factory settings for

the PW_ENA and PW_ENB (Table 02h, Registers C0h–

C1h) registers.

Memory Addresses A0h, A2h, and B2h

There are three separate I2C addresses in the DS1876:

A0h, A2h, and B2h. A2h and B2h are used to configure

and monitor two transmitters. Transmitter 1 is accessed

using A2h. Transmitter 2 is accessed using B2h. Many

of the registers in A2h and B2h are shared registers.

These registers can be read and written from both A2h

and B2h.

ACCESS CODE

READ ACCESS

WRITE ACCESS

<0/_>

At least 1 byte/bit in the row/byte is different than the rest of the row/byte, so look at each byte/bit

separately for permissions.

<1/_>

Read all

Write PW2

<2/_>

Read all

Write not applicable

<3/_>

Read all

Write all, but the DS1876 hardware also writes to

these bytes/bits

<4/_>

Read PW2

Write PW2 + mode_bit

<5/_>

Read all

Write all

<6/_>

Read not applicable

Write all

<7/_>

Read PW1

Write PW1

<8/_>

Read PW2

Write PW2

<9/_>

Read not applicable

Write PW2

<10/_>

Read PW2

Write not applicable

<11/_>

Read all

Write PW1

MEMORY CODE

A2h AND B2h REGISTERS

A common memory location is used for A2h and B2h device addresses. Reading or writing to these

locations is identical, regardless of using A2h or B2h addresses.

Different memory locations are used for A2h and B2h device addresses.

Mixture of common and different memory locations for A2h and B2h device addresses. See the individual

bytes within the row for clarification. If “M” is used on an individual byte, see the expanded bit descriptions

to determine which bits are common vs. different.

DS1876 Datasheet(PDF) 24 Page - Maxim Integrated Products

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