tda9874aps NXP Semiconductors, tda9874aps Datasheet - Page 17

• Manufacturer Part Number: tda9874aps
• Description: Digital Tv Sound Demodulator/decoder
• Manufacturer: NXP Semiconductors

Philips Semiconductors
7.3
As a slave receiver, the TDA9874A provides 26 registers
for storing commands and data. Each register is accessed
via a so-called subaddress. A subaddress can be thought
of as a pointer to an internal memory location.
Detailed descriptions of the slave receiver registers are
given in Sections 7.3.2 to 7.3.21.
It is allowed to send more than one data byte per
transmission to the TDA9874A. In this event, the
subaddress is automatically incremented after each data
byte, resulting in storing the sequence of data bytes at
successive register locations, starting at SUBADDRESS.
A transmission can start at any valid subaddress. Each
byte that is properly stored, is acknowledged with
A (acknowledge).
Table 7 I
Table 8 Explanation of Table 7
Table 9 Format for a transmission employing auto-increment of subaddresses
Note
1. n data bytes with auto-increment of subaddresses.
7.3.1
The TDA9874A can be programmed in the same way as
its predecessor (TDA9874H) using the
subaddresses 0 to 24 or by using ESP.
2000 Aug 04
S
SLAVE ADDRESS
0
A
SUBADDRESS
DATA
P
Digital TV sound demodulator/decoder
S
S
Slave receiver mode
P
2
ROGRAMMING VIA THE
C-bus; slave address, subaddress, data format
SLAVE ADDRESS
SLAVE ADDRESS
BIT
I
2
C-
BUS
0
0
A
A
START condition
7-bit device address
data direction bit (write to device)
acknowledge
address of register to write to
data byte to be written into register
STOP condition
SUBADDRESS
SUBADDRESS
17
subaddress, the device acknowledges with A (not
acknowledge), therefore telling the I
the transmission. There is no ‘wrap-around’ of
subaddresses.
Commands and data will be processed as soon as they
have been received completely. Functions requiring more
than one byte will thus be executed only after all bytes for
that function have been received. If the transmission is
terminated (STOP condition) before all bytes have been
received, the incomplete data for that function is ignored.
Data patterns sent to the various subaddresses are not
checked for being illegal or not at that address, except for
the level adjustment functions.
Detection of a STOP condition without a preceding
acknowledge bit is regarded as a bus error. In this case,
the last operation will not be executed.
7.3.1.1
While programming the TDA9874A, by writing to
subaddresses 0 to 24, it is not allowed to access
subaddress 255. Writing data to subaddress 255 will
overwrite the data previously written to subaddresses
3 to 10. This may cause unwanted effects.
If an attempt is made to write data to a non-existing
Programming via subaddresses 0 to 24
A
A
FUNCTION
BYTE A
DATA
DATA
(1)
2
C-bus master to abort
DATA
Product specification
TDA9874A
A
A
P
P