mc68hc05bs8 Freescale Semiconductor, Inc, mc68hc05bs8 Datasheet - Page 85

• Manufacturer Part Number: mc68hc05bs8
• Description: Mc68hc05 Family Of Low-cost Single-chip Microcontrollers.
• Manufacturer: Freescale Semiconductor, Inc

9.10.2
This 9-bit (the 9th bit is in bit 7 of LFHR at $0C) read only register is used to calculate the vertical
frame frequency. A 10-bit counter counts the number of internal clocks between two VSYNC
pulses. The counted value will then be transferred to this register. The data corresponds to the
period of one vertical frame. This register can be read to determine if the frame frequency is valid,
and to determine the video mode. Note that data is valid only if VDET= 1.
The frame frequency is calculated by 1/((VFR 1 + 240)x16t
Table 9-1 shows sample values for the Vertical Frequency register, all VFR numbers are in
hexadecimal
9.10.3
This 12-bit read only register pair contains the number of lines in each vertical frame. An internal
line counter counts the number of horizontal sync pulses between two vertical sync pulses and
then transfers the counted value to this register. The data can be read to determine if the line
frequency is valid, and to determine the video mode. Note that data is valid only if
HDET=VDET= 1.
The VF8 bit is the ninth bit of the Vertical Frequency register (VFR).
MC68HC05BS8
LFHR
LFLR
VFR
.
Vertical Frequency Register (VFR)
Line Frequency Registers (LFRs)
$004
$005
$006
$007
VFR
Min. Freq.
127.6
127.0
126.5
126.0
Table 9-1 Vertical Frame Frequencies
Address bit 7
Address bit 7
$000B
$000C
$000D
SYNC SIGNAL PROCESSOR
Max. Freq.
VF7
VF8
LF7
128.6
128.1
127.6
127.0
bit 6
bit 6
VF6
LF6
bit 5
bit 5
VF5
LF5
$1FC
$1FD
$1FA
$1FB
VFR
bit 4
bit 4
VF4
LF4
CYC
LF11
bit 3
bit 3
VF3
Min. Freq.
LF3
).
41.8
41.8
41.7
41.7
LF10
bit 2
bit 2
VF2
LF2
Max. Freq.
bit 1
bit 1
VF1
41.9
41.8
41.8
41.8
LF9
LF1
bit 0
bit 0
VF0
LF8
LF0
0000 0000
0000 0000
0000 0000
on reset
on reset
State
State
TPG
9