Analog Devices ADV8005, Hardware Reference Manual

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UG-707 ADV8005 Hardware Reference Manual
2.2.13. VGA Position and Phase Information
The ADV8005 can measure picture position and sample quality information and record these in on-chip registers. This information can be read
and used by the software on an external MCU to program the optimum sampling clock frequency and phase for an external Video AFE when it
is sampling a VGA-type input signal.
Figure 48: Autoposition and Phase Block Diagram
Figure 49: Autoposition and Phase Implementation Using System Firmware
The autophase block within the ADV8005 is designed to tune the ADC sampling phase in a device with an analog front end such as the
ADV7850, ADV7844, or ADV7842. Figure 48 shows a system view of how the ADV8005 implements autoposition and phase. Figure 49 shows
a block diagram of how the ADV8005 interfaces with the system software to tune the analog front end device, the ADV7850. For the autophase
the software driver cycles through each of the ADV7850 ADC sampling phases. The ADV8005 analyzes the input video timing and then
rb_auto_ph_right_phase[5:0] indicates the best sampling phase to use. The software routine required to implement this routing is decribed in
Figure 50 .
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