Free Run Mode; Free Run Mode Thresholds - Analog Devices Advantiv ADV7604 Hardware Manual

10.13 Free Run Mode

Free run mode provides the user with a stable clock and predictable data if the input signal cannot
be decoded, for example, if input video is not present. It controls default color insertion and causes
the ADV7604 to generate a default clock. The state in which this happens can be monitored via the
status bit CP_FREE_RUN. Refer to Section
configured automatically for analog modes. The free run feature must be configured for HDMI
modes.
Note
• When in free run mode, Macrovision and CGMS detections are not available.

10.13.1 Free Run Mode Thresholds

The free run threshold parameters define the horizontal and vertical conditions under which free run
mode is entered. The horizontal and vertical parameters of the incoming video signal are measured
and compared with internally stored parameters, and the magnitude of the difference decides
whether to enter free run. The internally stored parameters are decoded by default from
PRIM_MODE[3:0] and VID_STD[5:0].
of PRIM_MODE[3:0] and
CH1_F_RUN_TH[2:0] , CH1 Free Run Threshold Select , CP Map, Address 0xF3, [2:0]
CH2_F_RUN_TH[2:0], CH2 Free Run Threshold Select , CP Map, Address 0x43, [2:0]
In the case of the horizontal conditions, the length of the incoming video line is measured based on
the 28.6363 MHz crystal clock. This value is compared with the internally stored horizontal
parameter, the ideal line length. The controls bits CH1_F_RUN_TH[2:0] and
CH2_F_RUN_TH[2:0] allow the user to select the threshold for channel 1 and channel 2
respectively. The ideal line length can be manually set via the Free-run Line Length controls,
CH1_FR_LL[10:0] and CH2_FR_LL[10:0].
Function
CH1_F_RUN_TH
[2:0]/
CH2_F_RUN_TH
[2:0]
000
001
010
011
100
101
110
111
Rev. F August 2010
10.14
For video standards other than the preprogrammed settings
VID_STD[5:0], the parameters can be set manually.
Description
Minimum Difference to
Switch into Free Run
2
256
128
64
32
16
8
4
300
for more information. The free run feature is
Maximum Error to Switch out of
Free Run
1
200
112
48
24
12
6
3
ADV7604