MC68HC705BD3 FREESCALE [Freescale Semiconductor, Inc], MC68HC705BD3 Datasheet - Page 66

• Manufacturer Part Number: MC68HC705BD3
• Description: High-density complementary metal oxide semiconductor (HCMOS) microcontroller unit
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

8
8-6
Counter signal reset
System Clock
PH2 16
case1
PH2 16
case2
1. The value of the counter will be loaded into the register before it is reset.
2. The Vertical Frequency Counter is clocked by a PH2 16 clock.
3. Because of the asynchronous nature between PH2 and VSYNIN, the register
VSYNIN
will have one more count in case 2 than in case 1.
HSYNC
VSYNC
PH2
Figure 8-4 Sync Signal Counters Block Diagram
Figure 8-5 Vertical Frequency Counter Timing
Counter resets at 4 PH2 cycles
after falling edge of VSYNIN
SYNC SIGNAL PROCESSOR
Negative edge detector
Negative edge detector
Counter advances at the
rising edge of the clock
16
$0D
$0E
$0F
$10
12-bit Horizontal Line Count Register
13-bit Vertical Frequency Register
13-bit counter
12-bit counter
R
R
MC68HC05BD3
TPG