TDA7345 Datasheet, PDF (8/18 Pages) STMicroelectronics – DIGITALLY CONTROLLED AUDIO PROCESSOR WITH SURROUND SOUND MATRIX

TDA7345
SOFTWARE SPECIFICATION
Interface Protocol
The interface protocol comprises:
A start condition (s)
A chip address byte, containing the TDA7345
address (the 8th bit of the byte must be 0).
The TDA7345 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)
TDA7345 ADDRESS
MSB
LSB
MSB
S 1 0 0 0 0 0 1 0 ACK
D94AU194
DATA
LSB
MSB
ACK
DATA
LSB
ACK S
Data Transferred (N-bytes + Acknowledge)
ACK = Achnowledge
S = Start
P = Stop
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 TDA7345
can receive how many data as wanted for the
selected subaddress (without the need for a
new start condition)
- If TDA7345 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.
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
TDA7345 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:
EXAMPLES
S = start
ACK = acknowledge
1) NO INCREMENTAL BUS
B = 1 incremental bus, B = 0 no incremental bus
TDA7345 receives a start condition, the correct P = stop
1) one subaddress, with n data concerning that subaddress (no incremental bus)
CHIP ADDRESS
SUBADDRESS
DATA 1 ... DATA n
MSB
LSB
MSB
LSB
MSB
S 1 0 0 0 0 0 1 0 ACK 0 A0 A1 A2 A3 X X 0 ACK 1
D94AU195
DATA
LSB
ACK P
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