ADV7181BBCPZ datasheet(60/96 Pages) AD

60 / 96 page

ADV7181B

Rev. 0 | Page 60 of 96

The MPU can write to or read from all of the ADV7181B’s

registers, except the Subaddress register, which is write-only.

The Subaddress register determines which register the next read

or write operation accesses. All communications with the part

through the bus start with an access to the Subaddress register.

Then, a read/write operation is performed from/to the target

address, which then increments to the next address until a stop

command on the bus is performed.

The following sections describe each register in terms of its

configuration. The Communications register is an 8-bit, write-

only register. After the part has been accessed over the bus and a

read/write operation is selected, the subaddress is set up. The

Subaddress register determines to/from which register the

operation takes place. Table 81 lists the various operations

under the control of the Subaddress register for the control port.

These bits are set up to point to the required starting address.

I2C SEQUENCER

An I2C sequencer is used when a parameter exceeds eight bits,

and is therefore distributed over two or more I2C registers, for

example, HSB [11:0].

When such a parameter is changed using two or more I2C write

operations, the parameter may hold an invalid value for the

time between the first I2C being completed and the last I2C

being completed. In other words, the top bits of the parameter

may already hold the new value while the remaining bits of the

parameter still hold the previous value.

To avoid this problem, the I2C sequencer holds the already

updated bits of the parameter in local memory; all bits of the

parameter are updated together once the last register write

operation has completed.

The correct operation of the I2C sequencer relies on the

following:

•

All I2C registers for the parameter in question must be

written to in order of ascending addresses. For example, for

HSB[10:0], write to Address 0x34 first, followed by 0x35.

•

No other I2C taking place between the two (or more) I2C

writes for the sequence. For example, for HSB[10:0], write

to Address 0x34 first, immediately followed by 0x35.

ADV7181BBCPZ Datasheet(PDF) 60 Page - Analog Devices

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