HD9084 HDTV Caption Encoder Manual
Page 6-2 TROUBLESHOOTING
6.2. PARALLEL GPI/O PORT EXAMPLE APPLICATIONS
It is straight-forward to fabricate a DB15 plug with wires soldered across certain pins to make a custom
“GPI/O dongle” for use with the HD9084 Parallel I/O connector. This can be used to implement new
features not otherwise available in the HD9084. In the follwing example applications, the GPI and GPO
pins were selected arbitrarily; any available GPI and GPOs on the Parallel I/O connector could be used.
6.2.1. Automatic Upstream Caption Source Selection (defaults to HD-SDI)
This configuration will switch the upstream caption source to the HD-SDI input unless a CEA-608 line-
21 waveform is seen on field-1 of the SD-SDI input. If a CEA-608 waveforn is present, SD-SDI will be
selected as the upstream caption source. The GPO 2 Deassert Delay determines how long the HD9084
will continue to look at the SD-SDI input for upstream captions if the CEA-608 waveform disappears.
Fabricate the GPI/O dongle as follows:
Connect pins 10 and 15 to provide pullup voltage for GPI/O.
Connect GPO2 [pin 2] to GPIA [pin 8].
In the front panel menus, configure the following settings:
Set PORTS → GPI/O CONFIG → GPO 2 Stimulus = SD 608 Fld1 wfm
Set PORTS → GPI/O CONFIG → GPO 2 Active Level = High
Set PORTS → GPI/O CONFIG → GPO 2 Assert Delay = 0 seconds (switch immediately to SD-SDI)
Set PORTS → GPI/O CONFIG → GPO 2 Deassert Delay = 0.5 seconds (delay switching to HD-SDI)
Set PORTS → GPI ACTIVE LVLS → GPI A Active Level = Low
Set VIDEO → UPSTREAM CAPS → No Input Source = OFF
Set VIDEO → UPSTREAM CAPS → SD-SDI Input Source = ON
Set VIDEO → UPSTREAM CAPS → HD-SDI Input Source = GPI A
NOTE: For most applications, the CDPs will contain good CEA-608 and probably CEA-708 that was
derived by translating the 608 data. Recommended configuration is to leave the HD9084 translator
setup to translate CEA-608 CC1 to CEA-708 service-1 always.
6.2.2. Automatic Upstream Caption Source Selection (defaults to SD-SDI)
This configuration will switch the upstream caption source to the SD-SDI input unless Caption
Distribution Packets (CDPs) are present on the HD-SDI input video. If there are Caption Distribution
Packets (CDPs) appearing regularly on HD-SDI input video, HD-SDI will be selected as the upstream
caption source. The GPO 2 Deassert Delay determines how long the HD9084 will continue to look at
the HD-SDI input for upstream captions if the CDPs disappear.
Fabricate the GPI/O dongle as follows:
Connect pins 10 and 15 to provide pullup voltage for GPI/O.
Connect GPO2 [pin 2] to GPIA [pin 8].
In the front panel menus, configure the following settings:
Set PORTS → GPI/O CONFIG → GPO 2 Stimulus = HD VANC CDP detect
Set PORTS → GPI/O CONFIG → GPO 2 Active Level = Low
Set PORTS → GPI/O CONFIG → GPO 2 Assert Delay = 0 seconds (switch immediately to HD-SDI)
Set PORTS → GPI/O CONFIG → GPO 2 Deassert Delay = 0.5 seconds (delay switching to SD-SDI)
Set PORTS → GPI ACTIVE LVLS → GPI A Active Level = Low
Set VIDEO → UPSTREAM CAPS → No Input Source = OFF
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