GS4910B GENNUM [Gennum Corporation], GS4910B Datasheet - Page 28

• Manufacturer Part Number: GS4910B
• Description: HD/SD/Graphics Clock and Timing Generator with GENLOCK
• Manufacturer: GENNUM [Gennum Corporation]

Table 1-3: Output Timing Signals (Continued)
Signal Name
Audio Frame Sync
(GS4911B only)
USER_1~4
Description
The Audio Frame Sync (AFS) signal is HIGH (default polarity) for the duration of
the first line of the n’th video frame to indicate that the ACLK dividers are reset
at the start of line 1 of that frame. It is defined according to the frame rate of the
video format and the selected audio sample rate programmed via the
VID_STD[5:0] and ASR_SEL[2:0] pins or the host interface.
For example, if the video format is based on a 59.94Hz frame rate and the
audio sample rate clock is 48kHz, then n=5, and the AFS signal will be identical
to the 10FID signal.
By default, the AFS signal is reset by the 10 Field Identification (10FID)
reference input. This feature may be disabled using the Audio_Control register
at address 31h of the host interface (see
signal may also be reset using register 1Ah of the host interface. With no
reference, the frame divide by “n” controlling the AFS signal will free-run at an
arbitrary phase.
The default polarity of this signal may be inverted by programming the Polarity
register at address 56h of the host interface (see
Please see
The GS4911B/GS4910B offers four user programmable output signals. Each
USER signal is controlled by four timing registers and a polarity select bit. The
timing registers define the start and stop times in H pixels and V lines and begin
at address 57h of the host interface (see
Each user signal is individually programmable and the polarity, position, and
width of each output may be defined with respect to the H, V, and F output
timings of the device. Each output signal may be programmed in both the
horizontal and vertical dimensions relative to the leading edges of H and V
Sync. If desired, the pulses produced may then be combined with a logical
AND, OR, or XOR function to produce a composite signal (for example, a
horizontal back porch pulse during active lines only, or the active part of lines 15
through 20 for vertical information retrieval). Each output has selectable
polarity.
Please see
signals.
36655 - 2
Section 3.8.2 on page 68
Section 3.8.3 on page 69
April 2006
for more detail on the AFS output signal.
for more detail on the USER_1~4 output
Section 3.12.3 on page
Section 3.12.3 on page
Section
3.12.3).
GS4911B/GS4910B Data Sheet
79). The AFS
79).
Default Output Pin
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