REV. 0

ADM1032

–8–

to it. If the R/

W bit is a 0, the master will write to the slave

device. If the R/

W bit is a 1, the master will read from the

slave device.

2. Data is sent over the serial bus in sequences of nine clock

pulses, eight bits of data followed by an Acknowledge Bit

from the slave device. Transitions on the data line must

occur during the low period of the clock signal and remain

stable during the high period, as a low-to-high transition

when the clock is high may be interpreted as a STOP signal.

The number of data bytes that can be transmitted over the

serial bus in a single Read or Write operation is limited only

by what the master and slave devices can handle.

3. When all data bytes have been read or written, stop condi-

tions are established. In Write mode, the master will pull the

data line high during the tenth clock pulse to assert a STOP

condition. In Read mode, the master device will override the

acknowledge bit by pulling the data line high during the low

period before the ninth clock pulse. This is known as No

Acknowledge. The master will then take the data line low

during the low period before the tenth clock pulse, then high

during the tenth clock pulse to assert a STOP condition.

Any number of bytes of data may be transferred over the serial

bus in one operation, but it is not possible to mix read and write

in one operation because the type of operation is determined at

the beginning and cannot subsequently be changed without

starting a new operation.

In the case of the ADM1032, write operations contain either one

or two bytes, while read operations contain one byte, and per-

form the following functions:

To write data to one of the device data registers or read data

from it, the Address Pointer Register must be set so that the

correct data register is addressed, then data can be written into

that register or read from it. The first byte of a write operation

always contains a valid address that is stored in the Address

Pointer Register. If data is to be written to the device, the write

operation contains a second data byte that is written to the

register selected by the address pointer register.

This is illustrated in Figure 3a. The device address is sent over

the bus followed by R/

W set to 0. This is followed by two data

bytes. The first data byte is the address of the internal data

register to be written to, which is stored in the Address Pointer

Register. The second data byte is the data to be written to the

internal data register.

When reading data from a register there are two possibilities:

1. If the ADM1032’s Address Pointer Register value is unknown

or not the desired value, it is first necessary to set it to the

correct value before data can be read from the desired data

register. This is done by performing a write to the ADM1032

as before, but only the data byte containing the register read

address is sent, as data is not to be written to the register.

This is shown in Figure 3b.

A read operation is then performed consisting of the serial bus

address, R/

W bit set to 1, followed by the data byte read from

the data register. This is shown in Figure 3c.

2. If the Address Pointer Register is known to be already at the

desired address, data can be read from the corresponding

data register without first writing to the Address Pointer

Register and Figure 3b can be omitted.

Table VIII. List of ADM1032 Registers

Read Address (Hex)

Write Address (Hex)

Name

Power-On Default

Not Applicable

Not Applicable

Address Pointer

Undefined

00

Not Applicable

Local Temperature Value

0000 0000 (00h)

01

Not Applicable

External Temperature Value High Byte

0000 0000 (00h)

02

Not Applicable

Status

Undefined

03

09

Configuration

0000 0000 (00h)

04

0A

Conversion Rate

0000 1000 (08h)

05

0B

Local Temperature High Limit

0101 0101 (55h) (85

°C)

06

0C

Local Temperature Low Limit

0000 0000 (00h) (0

°C)

07

0D

External Temperature High Limit High Byte

0101 0101 (55h) (85

°C)

08

0E

External Temperature Low Limit High Byte

0000 0000 (00h) (0

°C)

Not Applicable

0F

One-Shot

10

Not Applicable

External Temperature Value Low Byte

0000 0000

11

11

External Temperature Offset High Byte

0000 0000

12

12

External Temperature Offset Low Byte

0000 0000

13

13

External Temperature High Limit Low Byte

0000 0000

14

14

External Temperature Low Limit Low Byte

0000 0000

19

19

External

THERM Limit

0101 0101 (55h) (85

°C)

20

20

Local

THERM Limit

0101 0101 (55h) (85

°C)

21

21

THERM Hysteresis

0000 1010 (0Ah) (10

°C)

22

22

Consecutive

ALERT

0000 0001 (01h)

FE

Not Applicable

Manufacturer ID

0100 0001 (41h)

FF

Not Applicable

Die Revision Code

Undefined

Writing to address 0F causes the ADM1032 to perform a single measurement. It is not a data register as such and it does not matter what data is written to it.