INTERFACE FEATURES

- Due to the fact that the MSB is used to select

if the byte transmitted is a subaddress (func-

tion) or a data (value), between a start and

stop condition, is possible to receive, how

many subaddresses and datas as wanted.

- The subaddress (function) is fixed until a new

subaddress is transmitted, so the TDA7344

can receive how many data as wanted for the

selected subaddress (without the need for a

new start condition)

- If TDA7344 receives a subaddress with the

LSB = 1 the incremental bus is selected, so it

enters in a loop condition that means that

every acknowledge will increase automat-

ically the subaddress (function) and it re-

ceives the data related to the new subad-

dress.

EXAMPLES

1) NO INCREMENTAL BUS

TDA7344 receives a start condition, the correct

chip address, a subaddress with the LSB = 0 (no

incremental bus), N-datas (all these datas con-

cern the subaddress selected), a new subad-

dress, N-data, a stop condition.

So it can receive in a single transmission how

many subaddress are necessary, and for each

subaddress how many data are necessary.

2) INCREMENTAL BUS

TDA7344 receives a start condition, the correct

chip address a subaddress with the LSB = 1 (in-

cremental bus): now it is in a loop condition with

an autoincrease of the subaddress.

The first data that it receives doesn’t concern the

subaddress sended but the next one, the second

one concerns the subaddress sended plus two in

the loop etc, and at the end it receives the stop

condition.

In the pictures there are some examples:

S = start

A

CHIP ADDRESS

0

80 (HEX)

1

82 (HEX)

ACK = acknowledge

B = 1 incremental bus, B = 0 no incremental bus

P = stop

SOFTWARE SPECIFICATION

Interface Protocol

The interface protocol comprises:

A start condition (s)

A chip address byte, containing the TDA7344

address (the 8th bit of the byte must be 0). The

TDA7344 must always acknowledge at the end

of each transmitted byte.

A subaddress (function) bytes (identified by the

MSB = 0)

A sequence of dates and subaddresses (N

bytes + achnowledge. The dates are identified

by MSB = 1, subaddresses by MSB = 0)

A stop condition (P)

1) one subaddress, with n data concerning that subaddress (no incremental bus)

ACK = Achnowledge

S = Start

P = Stop

TDA7344

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