MTV012A Просмотр технического описания (PDF) - Myson Century Inc
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MTV012A Datasheet PDF : 14 Pages
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MYSON
TECHNOLOGY
MTV012A
4. H/V SYNC Processing
The H/V SYNC processing block performs the functions of composite signal separation, SYNC input
presence check, frequency counting, and polarity detection and control, as well as protection of
VBLANK output while VSYNC speeds up to a high DDC communication clock rate. The present and
frequency function block treat any pulse shorter than 1 OSC period as noise.
4.1 Composite SYNC Separate
MTV012A continuously monitors the input HSYNC. If the vertical SYNC pulse can be extracted from the
input, a CVpre flag is set and the user can select the extracted "CVSYNC" for the source of polarity
check, frequency count and VBLANK. The CVSYNC will have a 10-16 us delay compared to the original
signal. The delay depends on the OSC frequency and composite mix method.
4.2 H/V Frequency Counter
MTV012A can discriminate between HSYNC/VSYNC frequency and saves the information in XFRs. The
15-bit H counter counts the time of the 64xHSYNC period, but only 11 upper bits are loaded into the
HCNTH/HCNTL latch.
The 11-bit output value will be (2/Hfreq) / (1/OSCfreq), updated once per VSYNC/CVSYNC period when
VSYNC/CVSYNC is present, or continuously updated when VSYNC/CVSYNC is not present. The 14-bit
V counter counts the time between 2 VSYNC pulses, but only 9 upper bits are loaded into the
VCNTH/VCNTL latch. The 9-bit output value will be (1/Vfreq) / (512/OSCfreq), updated every
VSYNC/CVSYNC period. An extra overflow bit indicates the condition of H/V counter overflow. The
VFchg/HFchg interrupt is active when VCNT/HCNT value changes or overflows. Tables 4.2.1 and 4.2.2
show the HCNT/VCNT value under the 8MHz OSC operations.
4.2.1 H-Freq Table
H-Freq(KHZ)
Output Value (11 bits)
8MHz OSC (hex / dec) 12MHz OSC (hex / dec)
1
30
215h / 533
320h / 800
2
31.5
1FBh / 507
2F9h / 761
3
33.5
1DDh /477
2CCh / 716
4
35.5
1C2h / 450
2A4h / 676
5
36.8
1B2h / 434
28Ch / 652
6
38
1A5h / 421
277h / 631
7
40
190h / 400
258h / 600
8
48
14Dh / 333
1F4h / 500
9
50
140h / 320
1E0h / 480
10
57
118h / 280
1A5h / 421
11
60
10Ah / 266
190h / 400
12
64
0FAh / 250
177h / 375
13
100
0A0h / 160
0F0h / 240
*1. The H-Freq output (HF10 - HF0) is valid.
*2. The tolerance deviation is + 1 LSB.
4.2.2 V-Freq Table
V-Freq(Hz)
1
56.25
2
59.94
3
60
4
60.32
Output Value (9 bits)
8MHz OSC (hex / dec) 12MHz OSC (hex / dec)
115h / 277
1A0h / 416
104h / 260
187h / 391
104h / 260
186h / 390
103h / 259
184h / 388
MTV012A Revision 1.1 12/23/1998
5/14
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