GS9092ACNE3 datasheet(28/63 Pages) GENNUM

28 / 63 page

GS9092A GenLINX® III 270Mb/s Serializer for SDI and

DVB-ASI

Data Sheet

34715 - 4

May 2010

28 of 63

box A of Figure 3-6). When the FIFO_EMPTY flag goes HIGH, the device will insert K28.5

stuffing data bytes.

To allow larger K28.5 packet sizes to be inserted, a write pointer offset can be

programmed into the FIFO_EMPTY_OFFSET[9:0] register of the host interface. If an

offset value is programmed in this register, the FIFO_EMPTY flag is set HIGH when the

read and write pointers of the FIFO are at the same address, and will remain HIGH until

the write pointer reaches the programmed offset. While the FIFO_EMPTY flag is HIGH,

the device will continue to insert stuffing characters. Once the pointer offset has been

exceeded, the FIFO_EMPTY flag will go LOW and the device will begin reading MPEG

data out of the FIFO (see box B of Figure 3-6).

In the case where the read pointer is originally ahead of the write pointer, the

FIFO_FULL flag will be set HIGH when both pointers arrive at the same address (see box

C of Figure 3-6). The application layer can use this flag to determine when to write to the

device.

A read and write pointer offset may also be programmed in the FIFO_FULL_OFFSET[9:0]

FIFO_FULL flag will be set HIGH when the read and write pointers of the FIFO are at the

same address, and will remain set HIGH until the read pointer reaches the programmed

offset. Once the pointer offset has been exceeded, the FIFO_FULL flag will be cleared

(see box D of Figure 3-6).

NOTE: When the FIFO is configured for DVB-ASI mode, the INSSYNCIN pin is unused,

as synchronization characters are inserted based on the FIFO status flags. The pin

should be grounded. When the internal FIFO is bypassed in DVB-ASI mode, the

INSSYNCIN input assumes normal operation as described in Control Signal Inputs on

page 36.

GS9092ACNE3 Datasheet(PDF) 28 Page - Gennum Corporation