GS6151 Datasheet, PDF (17/77 Pages) Semtech Corporation – Multi-Rate 6G UHD-SDI

4.1.2 Input Selection
The GS6151 incorporates a 2:1 input selector which allows the connection of two
independent streams of video/data.
The selector is controllable in three separate ways:
1. The DDI_SEL/STROBE pin can be used to select the input.
2. A GSPI accessible register can be used to select the input, with the state change
occurring as soon as the register value changes.
3. A GSPI accessible register can be used to select the input, with a rising edge on the
STROBE pin triggering a change to the next state.
Since these states are mutually exclusive, the DDI_SEL pin is shared with the STROBE
function.
In the case of using the DDI_SEL/STROBE pin (#1 above) or the STROBE pre-select
method (#3 above), the input selector will switch within 1μs of the change of state on
the corresponding pin(s). This strict timing requirement is not maintained when using
GSPI register selection (#2 above).
Each of the device’s two inputs is selected as shown in Table 4-2.
Table 4-2: Pin and Register Settings for Input Selection
Register Settings
INPUT_SELECTION_
CONTROL 7_h[9:8]
X0 (default)
X0 (default)
01
01
DDI_SELECT
7_h[10]
X
X
0
1
11
0
11
1
Note: ‘X’ indicates ‘Do Not Care’
DDI_SEL/STROBE
Differential
High-speed Input
Selected
LOW
HIGH
X
X
on LOW-to-HIGH
transition
on LOW-to-HIGH
transition
DDI0, DDI0
DDI1, DDI1
DDI0, DDI0
DDI1, DDI1
DDI0, DDI0
DDI1, DDI1
The DDI_SEL/STROBE pin includes an internal pull-down, which pulls the input voltage
LOW if the pin is left unconnected.
When using the STROBE pre-select method (#3 above), the pre-selected input buffer
and trace EQ is powered up in advance of the STROBE pulse.
GS6151
Final Data Sheet
PDS-060389
Rev.4
August 2015
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