ADM1192

Rev. B | Page 12 of 20

WRITE AND READ OPERATIONS

types of read and write operations. The operations used in the

ADM1192 are discussed in this section. Table 6 shows the

abbreviations used in the command diagrams (see Figure 21

to Figure 26).

Abbreviation

Condition

S

Start

P

Stop

R

Read

W

Write

A

Acknowledge

N

No acknowledge

QUICK COMMAND

The quick command operation allows the master to check if the

slave is present on the bus, as follows:

1.

The master device asserts a start condition on SDA.

2.

The master sends the 7-bit slave address, followed by the

write bit (low).

3.

The addressed slave device asserts an acknowledge on SDA.

4.

The master asserts a stop condition on SDA to end the

transaction.

S

SLAVE

ADDRESS

WA

12

3

P

4

Figure 21. Quick Command

WRITE COMMAND BYTE

In the write command byte operation, the master device sends

a command byte to the slave device, as follows:

1.

The master device asserts a start condition on SDA.

2.

The master sends the 7-bit slave address, followed by the

write bit (low).

3.

The addressed slave device asserts an acknowledge on SDA.

4.

The master sends the command byte. The command byte

is identified by an MSB = 0. An MSB = 1 indicates an

extended register write (see the Write Extended Command

Byte section).

5.

The slave asserts an acknowledge on SDA.

6.

The master asserts a stop condition on SDA to end the

transaction.

S

SLAVE

ADDRESS

WA

COMMAND

BYTE

AP

12

3

4

5 6

Figure 22. Write Command Byte

The seven LSBs of the command byte are used to configure and

control the ADM1192. Table 7 provides details of the function

of each bit.

Table 7. Command Byte Operations

Bit

Default

Name

Function

C0

0

V_CONT

LSB, set to convert voltage continuously. If readback is attempted before the first conversion is complete,

the ADM1192 asserts an acknowledge and returns all 0s in the returned data.

C1

0

V_ONCE

conversion is complete.

C2

0

I_CONT

Set to convert current continuously. If readback is attempted before the first conversion is complete,

the ADM1192 asserts an acknowledge and returns all 0s in the returned data.

C3

0

I_ONCE

conversion is complete.

C4

0

VRANGE

Selects different internal attenuation resistor networks for voltage readback. A 0 in C4 selects a 14:1 voltage

divider. A 1 in C4 selects a 7:2 voltage divider. With an ADC full scale of 1.902 V, the voltage at the VCC pin for

an ADC full-scale result is 26.52 V for VRANGE = 0 and 6.65 V for VRANGE = 1.

C5

0

N/A

Unused.

C6

0

STATUS_RD

Status Read. When this bit is set, the data byte read back from the ADM1192 is the status byte. This contains

the status of the device alerts. See Table 15 for full details of the status byte.