GS9090 Data Sheet
3.5.3 Manual Mode
Recall that the GS9090 is in Manual mode when the AUTO/MAN input pin is set
LOW by the application layer. In this mode the SMPTE_BYPASS and DVB_ASI
pins become input signals, and the application layer determines the operating
mode of the device by setting these pins as shown in Table 3-2
.
Table 3-2: Manual Mode Input Status Signals
Pin Settings
Format
SMPTE_BYPASS
DVB_ASI
SD SMPTE
DVB-ASI
HIGH
X
LOW
HIGH
LOW
NOT SMPTE OR DVB-ASI
(Data-Through mode)*
LOW
*NOTE: See Data-Through functionality on page 29 for more detail on Data-Through mode
3.6 SMPTE Functionality
The GS9090 enters SMPTE mode once the device has detected SMPTE TRS sync
words and locked to the input data stream as described in Lock Detect on page 22.
The GS9090 will remain in SMPTE mode until such time that SMPTE TRS sync
words fail to be detected.
The lock detect block may also drop out of SMPTE mode under any of the following
conditions:
•
•
•
SMPTE_BYPASS is asserted LOW in Manual mode
RESET is asserted LOW
LOCKED is LOW (i.e. the device loses lock to the input signal)
TRS word detection is a continuous process, and the device will identify both 8-bit
and 10-bit TRS words.
In Auto mode, the GS9090 sets the SMPTE_BYPASS pin HIGH and the DVB_ASI
pin LOW to indicate that it has locked to a SMPTE input data stream. When
operating in Manual mode, the application layer must assert the DVB_ASI pin LOW
and the SMPTE_BYPASS pin HIGH in order to enable SMPTE operation.
28201 - 1 July 2005
25 of 70
GENNUM [ GENNUM CORPORATION ]
