MC68HC908BD48 Datasheet, PDF (222/290 Pages) Freescale Semiconductor, Inc – Microcontrollers

Sync Processor
The frame frequency is calculated by:
Vertical Frame Frequency = -_V----_F---_R------_±-----₁-----_×-¹----₄---₈-----_×-----_t-_C---_Y---_C-
= _V-----_F---_R------_±----¹-₁-----_×-----₈---_µ----_s-
for internal bus clock of 6 MHz
Table 16-6 shows examples for the Vertical Frequency Register, all VFR
numbers are in hexadecimal.
Technical Data
222
Table 16-6. Sample Vertical Frame Frequencies
VFR
$02A0
$03C0
$03C1
$03C2
$04E2
$04E3
$04E4
$06F9
$06FA
$06FB
Max Freq.
186.20 Hz
130.34 Hz
130.21 Hz
130.07 Hz
100.08 Hz
100.00 Hz
99.92 Hz
70.07 Hz
70.03 Hz
69.99 Hz
Min Freq.
185.70 Hz
130.07 Hz
129.94 Hz
129.80 Hz
99.92 Hz
99.84 Hz
99.76 Hz
69.99 Hz
69.95 Hz
69.91 Hz
VFR
$0780
$0823
$0824
$0825
$09C4
$09C5
$09C6
$1FFD
$1FFE
$1FFF
Max Freq.
65.10 Hz
60.04 Hz
60.01 Hz
59.98 Hz
50.02 Hz
50.00 Hz
49.98 Hz
15.266 Hz
15.264 Hz
15.262 Hz
Min Freq.
65.00 Hz
59.98 Hz
59.95 Hz
59.92 Hz
49.98 Hz
49.96 Hz
49.94 Hz
15.262 Hz
15.260 Hz
15.258 Hz
VOF — Vertical Frequency Counter Overflow
This read-only bit is set when an overflow has occurred on the 13-bit
vertical frequency counter. Reset clears this bit, and will be updated
every vertical frame.
An overflow occurs when the period of Vsync frame exceeds
64.768ms (a vertical frame frequency lower than 15.258Hz).
1 = A vertical frequency counter overflow has occurred
0 = No vertical frequency counter overflow has occurred
Sync Processor
MC68HC908BD48 — Rev. 1.0
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