Analog Devices ADV8003, Hardware Manual

Page: 274 / 440

ADV8003 Hardware Manual
Rev. B, August 2013 274
Manual mode: Manual mode is selected by setting cts_sel to 1. In manual mode, the user can program the CTS number directly into the
chip via the cts_manual[19:0] field. Manual mode is good for coherent audio and video, where the audio and video clocks are generated
from the same crystal; thus CTS should be a fixed number.
Automatic mode:
Automatic mode is selected by setting cts_sel to 0. In automatic mode, the chip computes the CTS based on the actual
audio and video rates. The result can be read from the cts_internal[19:0] field. Automatic mode is good for incoherent audio or video,
where there is no simple integer ratio between the audio and video clock.
The 20-bit n value used by the Tx core of the ADV8003 can be programmed in the
n[19:0] field.
cts_sel
, TX2 Main Map,
Address 0xF40A[7]
This bit is used to specify whether CTS is automatically or manually set.
Function
cts_sel Description
0  Automatic CTS. Use the internally generated CTS value
1 Manual CTS. Use the CTS programmed via CTS_MANUAL[19:0]
cts_manual[19:0]
, TX2 Main Map, Address 0xF407[3:0]; Address 0xF408[7:0]; Address 0xF409[7:0]
This signal is used to manually set the Cycle Time Stamp (CTS). This parameter is used with the N parameter to regenerate the audio
clock in the Rx.
cts_internal[19:0]
, TX2 Main Map,
Address 0xF404[3:0]; Address 0xF405[7:0]; Address 0xF406[7:0] (Read Only)
This signal is used to readback the automatically generated Cycle Time Stamp (CTS) parameter. This parameter is used with the N
parameter to regenerate the audio clock in the Rx.
n[19:0] , TX2 Main Map, Address 0xF401[3:0]; Address 0xF402[7:0]; Address 0xF403[7:0]
This signal is used to specifies the audio clock regeneration parameter N. This parameter is used with CTS to regenerate the audio clock
in the Rx.
Table 62: Recommended N and Expected CTS Values for 32 kHz Audio
32 kHz
Pixel Clock (MHz) N CTS
25.2/1.001 4576 28125
25.2 4096 25200
27 4096 27000
27 * 1.001 4096 27027
54 4096 54000
54 * 1.001 4096 54054
74.25/1.001 11648 210937 – 210938
74.25 4096 74250
148.5/1.001 11648 421875
148.5 4096 148500
Other 4096 Measured