MAX16068 Datasheet, PDF(26/40 Page) Maxim Integrated Products – 6-Channel, Flash-Configurable System Manager with Nonvolatile Fault Registers

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6-Channel, Flash-Configurable System Manager

with Nonvolatile Fault Registers

Packet Error Checking (PEC)

The MAX16068 features a packet-error checking (PEC)

mode that is useful to improve the reliability of the com-

munication bus by detecting bit errors. By enabling PEC,

an extra CRC-8 error check byte is added in the data

string during each read and/or write sequence. Enable

PEC by writing a â1â to r8Bh[7].

The CRC-8 byte is calculated using the polynomial:

C = X8 + X2 + X + 1

The PEC calculation includes all bytes in the transmis-

sion, including address, command and data. The PEC

calculation does not include ACK, NACK, START, STOP,

or REPEATED START.

Command Codes

The MAX16068 uses eight command codes for block

read, block write, and other commands. See Table 20

for a list of command codes.

To initiate a software reboot, send A7h using the send

byte format. A software-initiated reboot is function-

ally the same as a hardware-initiated power-on reset.

During boot-up, flash configuration data in the range

of 230hâ28Ch is copied to r30hâr8Ch registers in the

default page.

Send command code A8h to trigger a fault store to flash.

Configure the Critical Fault Log Control register (6Dh) to

store ADC conversion results and/or fault flags.

While in the flash page, send command code A9h to

access the flash page (addresses from 200hâ2FFh).

Once command code A9h has been sent, all addresses

are recognized as flash addresses only. Send command

code AAh to return to the default page (addresses from

000hâ0FFh). Send command code ABh to access the

user flash-page (addresses from 300hâ3FFh), and send

command code ACh to return to the flash page.

Restrictions When Writing to Flash

Flash must be written to 8 bytes at a time. The initial

address must be aligned to 8-byte boundariesâthe 3

LSBs of the initial address must be â000â. Write the 8

bytes using a single block write command or using eight

successive Write Byte commands. A write operation

requires 122ms for each 8-byte block. After program-

ming a block, check r20h[1] (see Table 25) to make sure

the write operation is complete before attempting to write

the next block.

Table 19. SMBus Settings Register

ADDRESS

FLASH

ADDRESS

BIT RANGE

[6:0]

8Bh

28Bh

[7]

DESCRIPTION

SMBus Slave Address Register. Set to 00h to use A0 pin address

setting.

1 = Enable PEC (Packet Error Check).

Table 20. Command Codes

COMMAND CODE

A5h

A6h

A7h

A8h

A9h

AAh

ABh

ACh

ACTION

Block write

Block read

Reboot flash in register file

Trigger emergency save to flash

Flash page access ON

Flash page access OFF

User flash access ON (must be in flash page already)

User flash access OFF (return to flash page)

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