Readback Signals From Agc Block - Analog Devices ADV7850 Hardware Manual

Function
agc_tim[2:0]
000 
001
010
011
100
101
110
111

9.3.6.1 Readback Signals from AGC Block

The following readback signals are provided:
•
Presently used gain value can be read back through
• Depth of the synchronization pulse on channel A (before gaining) through
• Depth of the synchronization pulse on channel A (after gaining) through
•
Depth of the synchronization pulse on channel B (before gaining) through
• Depth of the synchronization pulse on channel C (before gaining) through
Notes:
•
hsd_fb[11:0] is provided to allow an off-chip AGC loop to be implemented in a feedback architecture.
• hsd_cha, hsd_chb, and hsd_chc[9:0] are provided to allow the user in GR modes to find out if all three channels have
synchronization pulses on them. If the input RGB has a synchronization pulse only on the Green channel and the CSC is used to
convert RGB to YPbPr levels, the synchronization depth on Y will be too shallow (compare with the conversion formula RGB to
YPbPr). agc_tar[9:0] must be used to enable proper output levels after the AGC.
• The hsd_cha[9:0] register information is also used to figure out if an AGC function is possible. Without a proper
synchronization pulse on the data in channel A, no AGC loop can work and manual gain control should be used.
cp_agc_gain[9:0], Addr 44 (CP), Address 0xE0[1:0]; Address 0xE1[7:0] (Read Only)
This readback displays the value of the gain used on the data of channel A. This value is in a 1.9 binary format and is composed of one
integer and nine fractional bits.
Function
cp_agc_gain[9:0]
xxxxxxxxxx
hsd_cha[9:0], Addr 44 (CP), Address 0xE7[1:0]; Address 0xE8[7:0] (Read Only)
This readback displays the measured value of the HSync depth on channel A before the gain multiplier. The value is presented in 1.9
binary format.
Function
hsd_cha[9:0]
xxxxxxxxxx
hsd_chb[9:0], Addr 44 (CP), Address 0xE7[3:2]; Address 0xE9[7:0] (Read Only)
This readback displays the measured value of the HSync depth on channel B before the gain multiplier. The value is presented in 1.9
binary format.
Rev. A May 2012
Description
100 lines
1 frame
0.5 sec
1 sec
2 sec
3 sec
5 sec
7 sec
cp_agc_gain[9:0]
Description
Readback value of gain
Description
Readback for measured value of HSync depth on channel A
hsd_cha[9:0]
hsd_fb[11:0]
hsd_chb[9:0]
hsd_chc[9:0]
249
ADV7850