adv7390 Analog Devices, Inc., adv7390 Datasheet - Page 46

• Manufacturer Part Number: adv7390
• Description: Low Power, Chip Scale 10-bit Sd/hd Video Encoder
• Manufacturer: Analog Devices, Inc.

ADV7390/ADV7391/ADV7392/ADV7393
ED/HD TIMING RESET
Subaddress 0x34, Bit 0
An ED/HD timing reset is achieved by setting the ED/HD
timing reset control bit (Subaddress 0x34, Bit 0) to 1. In this
state, the horizontal and vertical counters remain reset. When
this bit is set back to 0, the internal counters resume counting.
This timing reset applies to the ED/HD timing counters only.
SD SUBCARRIER FREQUENCY LOCK, SUBCARRIER
RESET, AND TIMING RESET
Subaddress 0x84, Bits[2:1]
Together with the SFL/MISO pin and SD Mode Register 4
(Subaddress 0x84, Bits[2:1]), the ADV739x can be used in
timing reset mode, subcarrier phase reset mode, or SFL mode.
•
In timing reset (TR) mode (Subaddress 0x84, Bits[2:1] = 10),
a timing reset is achieved in a low-to-high transition on the
SFL/MISO pin. In this state, the horizontal and vertical
counters remain reset. Upon releasing this pin (set to low),
the internal counters resume counting, starting with Field 1,
and the subcarrier phase is reset.
The minimum time the pin must be held high is one clock
cycle; otherwise, this reset signal may not be recognized.
This timing reset applies to the SD timing counters only.
DISPLAY
307
NO TIMING RESET APPLIED
TIMING RESET APPLIED
NO F
F
SC
307
307
307
RESET APPLIED
SC
RESET APPLIED
DISPLAY
Figure 63. SD Subcarrier Phase Reset Timing Diagram (Subaddress 0x84, Bits [2:1] = 01)
DISPLAY
DISPLAY
Figure 62. SD Timing Reset Timing Diagram (Subaddress 0x84, Bits [2:1] = 10)
310
310
310
1
START OF FIELD 1
2
3
313
313
313
4
START OF FIELD 4 OR 8
START OF FIELD 4 OR 8
START OF FIELD 4 OR 8
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5
6
F
7
SC
•
•
PHASE = FIELD 1
In subcarrier reset (SCR) mode (Subaddress 0x84, Bits[2:1]
= 01), a low-to-high transition on the SFL/MISO pin resets
the subcarrier phase to 0 on the field following the
subcarrier phase reset.
This reset signal must be held high for a minimum of one
clock cycle.
Because the field counter is not reset, it is recommended to
apply the reset signal in Field 7 (PAL) or Field 3 (NTSC).
The reset of the phase then occurs on the next field, that is,
Field 1, which is lined up correctly with the internal
counters. The field count register at Subaddress 0xBB can
be used to identify the number of the active field.
In subcarrier frequency lock (SFL) mode (Subaddress 0x84,
Bits[2:1] = 11), the ADV739x can be used to lock to an
external video source. The SFL mode allows the ADV739x
to automatically alter the subcarrier frequency to compensate
for line length variations. When the part is connected to a
device such as an ADV7403 video decoder that outputs a
digital data stream in the SFL format, the part automatically
changes to the compensated subcarrier frequency on a
line-by-line basis (see Figure 64). This digital data stream is
67 bits wide and the subcarrier is contained in Bit 0 to Bit
21. Each bit is two clock cycles long.
21
F
320
F
SC
320
320
SC
F
PHASE = FIELD 4 OR 8
SC
PHASE = FIELD 4 OR 8
PHASE = FIELD 1
TIMING RESET PULSE
F
SC
RESET PULSE