No. 5876-6/16

LC72709E, 72709W

• Layer 4 CRC Data Input Timing

Serial Control Data Input Settings

The input data consists of 16 bits (DI0 to DI15). The upper 8 bits (DI8 to DI15) are the control address and the lower 8

bits (DI0 to DI7) are the input data. Bits DI12 to DI15 are ignored.

• Number of Allowed BIC Errors

This IC’s synchronization circuit operates by recognizing a 16-bit BIC code. The number of allowed errors is the

number of allowed error bits in the 16 bits used for BIC recognition. This data item allows the forward protection mode

(used when synchronized) and the backward protection mode (used when not synchronized) values to be set

independently. The default value is to allow up to 2 error bits in both the forward and backward directions. We

recommend setting the backward protection mode number of allowable BIC errors to 1 or 0 if the block

synchronization recognition output (the BLOCK pin) is used to recognize the presence or absence of FM multiplex

data.

• Block Synchronization Error Protection Count

The synchronization protection count can be set independently in the forward and backward directions. The protection

count conditions are as follows.

— Backward protection (unsynchronized, BLOCK = low)

When the timing of the IC’s internal synchronization free-running counter matches that of the received BIC, the

protection count is incremented by 1. Similarly, if the IC internal counter and the received BIC do not match, the

counter is cleared to 0. The count timing is the timing of the IC internal counter.

— Forward protection (synchronized, BLOCK = high)

Operation is the opposite of the backward case, namely, the protection count is incremented when the timing of the

IC’s internal synchronization free-running counter does not match that of the received BIC, and the protection

count is cleared to zero when the timing matches.

Figure 1 shows the protection counter when both the forward and backward protection counts are set to 3.

This IC defines the protection counter value to be 1 at the point where a match or a mismatch occurs between the IC

internal timing and the received BIC timing. For example, a backward protection count of 2 corresponds to the case

where the IC internal timing and the received BIC timing match two times consecutively. To set the protection data to

new values, applications must send data in which 1 has been subtracted from the desired values, e.g. to set up protection

counts of 3 as shown in figure 1, applications must send the value 22H. Similarly, if the value set is 00, due to the

CRC4 pin output

Note: The N items are 8-bit units.

CRC4 output after N items transferred

Register

Address

Data

Default

DI11

DI10

DI9

DI8

setting

Number of allowable BIC errors

0

0

0

0

Upper 4 bits

Allowed error bits backward

2

Lower 4 bits

Allowed error bits forward

2

Number of block error protection states

0

0

0

1

Upper 4 bits

Block backward protection

1

Lower 4 bits

Block forward protection

7

Number of frame error protection states

0

0

1

0

Upper 4 bits

Frame backward protection

1

Lower 4 bits

Frame forward protection

7

Control register

0

0

1

1

See the control register description on page 8.

Continued on next page.