W78C354 Datasheet, PDF (33/44 Pages) Winbond – MONITOR MICROCONTROLLER

W78C354
V frequency:
• Resolution of V frequency counter: VRESOL = (1/FCLOCK ) × 16
• V-frequency: VFREQ = 1/(VCOUNT × VRESOL)
• Lowest V frequency can be detected: FCLOCK ¡Ò 1048576
H frequency:
• Resolution of H frequency counter: HRESOL = (1/FCLOCK) ¡Ò 8
• H-frequency: HFREQ = 1/(HCOUNT × HRESOL)
• Lowest H frequency can be detected: FCLOCK ¡Ò 8192
16 MHz
18.432 MHz
Vresol
1 µS
868 nS
Lowest VFREQ
15 Hz
17.6 Hz
Hresol
7.8 nS
6.8 nS
Lowest HFREQ
1.9 KHz
2.3 KHz
20 MHz
800 nS
19 Hz
6.3 nS
2.4 KHz
M-4. Dummy Frequency Generator
The dummy H and V frequencies are generated for factory burn-in measurement and for displaying a
warning message when there is no input H/V frequency. The dummy sync generator includes two
newly added SFRs, DHREG and DVREG. DHREG is a 4-bit register used to determine the dummy
Hsync output frequency. DVREG is an 8-bit register that can be used to preset a constant into
DVREG to determine the dummy Vsync output frequency by the formulas listed below.
• Dummy Hsync frequency FdH = FCLOCK ¡Ò 32 ¡Ò (DHREG+1)
• Dummy Vsync frequency FdV = FdH ¡Ò 8 ¡Ò (DVREG+1)
Example: Assume system clock = 16 Mhz
DHREG
FDH
15
31.25K
12
38.5K
10
45.5K
9
50K
7
62.5K
5
82K
4
100K
DVREG
48
59
70
77
96
127
155
FDV
79.7 Hz
80.2 Hz
80.1 Hz
80.1 Hz
80.5 Hz
80.1 Hz
80.1 Hz
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Publication Release Date: October 1996
Revision A1