AME, Inc.

7

ATTM01/ATTM02

Processor Thermal Monitor

Rev. B.01

8. SMBus Protocol

In this chip it supports the write byte and read byte mode protocol. The following is SMBus read/write data format.

Write Byte Format:

START

Slave

Address

WR

ACK

COMMAND

ACK

DATA

ACK

STOP

1 bit

7 bits

1 bit

1 bit

8 bits

1 bit

8 bits

1 bit

1 bit

The COMMAND Byte is selects that register you are writing to. The DATA Byte is data goes into the register set by

the command byte (to set thresholds, configuration, and update rate).

Read Byte Format:

S

Address

WR

ACK

COMMAND

ACK

S

Address1

RD

ACK

DATA

NAK

STOP

1 bit

7 bits

1 bit

1 bit

8 bits

1 bit

1 bit

8 bits

1 bit

1 bit

8 bits

1 bit

1 bit

The S denotes Start Bit. Address represents slave address. The COMMAND Byte is selects that register you are

reading from. The Address1 is due to change in data flow direction. The DATA Byte is reads from the register set by the

command byte. The in above table the red color denotes Slaver transmission.

SMBus Write Timing Diagram:

A

B

C

D

E

F

G

H

I

J

K

L

M

SMBCLK

SMBDATA

A = START CONDITION

B = MSB OF ADDRESS CLCOKED INTO SLAVE

C = LSB OF ADDRESS CLOCKED INTO SLAVE

D = R/W_ BIT CLOCKED INTO SLAVE

E = SLAVE PULL SMBDATA BUS LOW

F = ACKNOWLEDGE BIT CLOCKED INTO MASTER

G = MSB OF DATA CLOCKED INTO SLAVE

H = LSB OF DATA CLOCKED INTO SLAVE

I = SLAVE PULLS SMBDATA BUS LOW

J = ACKNOWLEDGE BIT CLOCKED INTO MASTER

K = ACKNOWLEDGE CLEAR PULSE

L = STOP CONDITION DATA EXECUTED BY SLAVE

M = NEW START CONDITION