|LC72710LW||Mobile FM Multiplex Broadcast (DARC) Receiver IC with On-Chip VICS Decoder|
SANYO -> Panasonic
|LC72710LW Datasheet PDF : 33 Pages |
This IC includes both registers that can be read and registers that can be written. These registers can be accessed using
either the serial interface (CCB) or the parallel interface. The SP pin switches between these interfaces.
The initial values of the write registers are the data loaded into internal registers when a reset signal (RST) is received.
These values are recommended values that do not need to be changed during normal operation.
If the parallel interface is used, applications must hold the address fixed at 00H when reading out data to which error
correction has been applied. If the CCB interface is used, the application needs only to specify the CCB address (#FB).
The address 00H is an invalid address for writing.
The addresses other than those specified below are control addresses particular to the IC. Applications must not specify
R/W Address Register
BIC Number of allowable BIC errors
STAT Status register
SYNCB Block synchronization: error protection count
BLNO Block number register
SYNCF Frame synchronization: error protection count W
CTL1 Control register 1
CTL2 Control register 2
CRC4 Layer 4 CRC register
Number of Allowable BIC Errors
Address Register R/W Initial value
The synchronization circuit in this IC operates by recognizing a 16-bit BIC code. The number of allowable errors is the
number of incorrect bits allowed in those 16 bits. This data sets up separate values for forward protection mode (when
synchronized) and for back protection mode (when not synchronized).
The default value is to allow 2 incorrect bits in both forward and back modes. If the block synchronization discrimination
output (BLOCK) is used for discriminating whether or not FM multiplex data is present, we recommend setting the back
protection mode BIC allowable error count to 1 or 0.
Block Synchronization: Error Protection Count
Address Register R/W Initial value
The synchronization protection count can be set separately for both forward and back protection. The count conditions
for the protection counts are as follows.
• Back protection mode (not synchronized: BLOCK = low)
If the timing of the IC internal synchronization free-running counter matches the timing of the received BIC, the
protection count is incremented by 1. Contrarily, if the timings of the IC internal counter and the received BIC do not
match, the protection counter is cleared to 0. The timing of the count is the timing of the IC internal counter.
• Forward protection mode (synchronized: BLOCK = high)
In reverse to the back protection mode, if the timing of the IC internal free-running counter does not match the
detection timing of the received BIC, the protection counter is incremented, and if the timings match, the protection
counter is cleared to 0.
Figure 1 shows the states of the protection counter for the cases where the forward and back protection counts are both 3.
This IC defines the value of the protection counter to be 1 at the point that a match or a discrepancy occures between the
IC internal timing and the timing of the received BIC. For example, when the value of the back protection count is 2, the
IC internal timing and the timing of the received BIC will have matched two times consecutively.
If the protection data is set to new values, for example if the protection counts are set to 3 as assumed in figure 1,
applications must send values which are 1 less than the intended value; in this case 22H. Similarly, if the value is set to
00H, the protection counts will, by definition, be set to 1 for both the forward and back directions. However, note that the
resulting operation will be equivalent to there being no protection circuit. The default values are 8 for the forward
protection count and 2 for the back protection count.
If the block synchronization output (BLOCK) is used for discriminating whether or not FM multiplex data is present, we
recommend setting the block synchronization back protection count to a value that is more strict than the default value.
(That is, we recommend replacing the default value of 2 with a value of 3 or higher.)
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