TDA7448
SOFTWARE SPECIFICATION
Interface Protocol
The interface protocol comprises:
■ A start condition (S)
■ A chip address byte, containing the TDA7448 address
■ A subaddress bytes
■ A sequence of data (N byte + acknowledge)
■ A stop condition (P))
CHIP ADDRESS
SUBADDRESS
DATA 1 to DATA n
DATA
MSB
1
LSB
0
MSB
X
LSB
MSB
LSB
S
0
0
0
1
0
0
ACK
X
X
B
DATA
ACK
ACK
P
D96AU420
ACK = Acknowledge;
S = Start;
P = Stop;
A = Address;
B = Auto Increment
EXAMPLES
No Incremental Bus
The TDA7448 receives a start condition, the correct chip address, a subaddress with the B = 0 (no incremental
bus), N-data (all these data concern the subaddress selected), a stop condition.
CHIP ADDRESS
SUBADDRESS
DATA
MSB
1
LSB
0
MSB
X
LSB
D3 D2 D1 D0 ACK
MSB
LSB
S
0
0
0
1
0
0
ACK
X
X
0
DATA
ACK
P
D96AU421
Incremental Bus
The TDA7448 receivea start conditions, the correct chip address, a subaddress with the B = 1 (incremental bus):
now it is in a loop condition with an autoincrease of the subaddress whereas SUBADDRESS from "XXX1000"
to "XXX1111" of DATA are ignored.The DATA 1 concern the subaddress sent, and the DATA 2 concern the
subaddress sent plus one in the loop etc, and at the end it receivers the stop condition.
CHIP ADDRESS
SUBADDRESS
DATA 1 to DATA n
MSB
1
LSB
0
MSB
X
LSB
D3 D2 D1 D0 ACK
MSB
LSB
S
0
0
0
1
0
0
ACK
X
X
1
DATA
ACK
P
D96AU422
DATA BYTES
Address= 88 (HEX) (10001000): ADDR open; 8A (HEX) (10001010): connect to supply
FUNCTION SELECTION: subaddress
MSB
D7
X
LSB
D0
0
SUBADDRESS
D6
X
D5
X
D4
B
D3
0
D2
0
D1
0
SPEAKER ATTENUATION OUT 1
SPEAKER ATTENUATION OUT 2
SPEAKER ATTENUATION OUT 3
SPEAKER ATTENUATION OUT 4
SPEAKER ATTENUATION OUT 5
SPEAKER ATTENUATION OUT 6
NOT USED”
X
X
X
B
0
0
0
1
X
X
X
B
0
0
1
0
X
X
X
B
0
0
1
1
X
X
X
B
0
1
0
0
X
X
X
B
0
1
0
1
X
X
X
B
0
1
1
0
X
X
X
B
0
1
1
1
NOT USED
B=1: INCREMENTAL BUS; ACTIVE
B=0: NO INCREMENTAL BUS
X= DON’T CARE
6/13
STMICROELECTRONICS [ ST ]
