M306V5EESP Mitsubishi, M306V5EESP Datasheet - Page 162

• Manufacturer Part Number: M306V5EESP
• Description: SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER and ON-SCREEN DISPLAY CONTROLLER
• Manufacturer: Mitsubishi

162
Figure 2.14.10 Clock run-in detect register
2.14.7 Reference Voltage Generating Circuit and Comparator
2.14.8 Start Bit Detecting Circuit
2.14.9 Clock Run-in Determination Circuit
The composite video signal clamped by the clamping circuit is input to the reference voltage generating
circuit and the comparator.
This circuit detects a start bit at line decided in the data slice line specification circuit.
The detection of a start bit is described below.
This circuit determinates clock run-in by counting the number of pulses in a window of the composite
video signal.
The reference clock count value in one pulse cycle is stored in bits 3 to 7 of the clock run-in detect register
(address 0269
Interrupt request generating circuit).
Figure 2.14.10 shows the structure of clock run-in detect register.
(1) Reference voltage generating circuit
(2) Comparator
A sampling clock is generated by dividing the reference clock output by the timing signal.
A clock run-in pulse is detected by the sampling clock.
After detection of the pulse, a start bit pattern is detected from the comparator output.
This circuit generates a reference voltage (slice voltage) by using the amplitude of the clock run-in
pulse in line specified by the data slice line specification circuit. Connect a capacitor between the
V
current may not be generated.
The comparator compares the voltage of the composite video signal with the voltage (reference volt-
age) generated in the reference voltage generating circuit, and converts the composite video signal
into a digital value.
HOLD
Clock run-in detect register
pin and the V
b7 b6 b5 b4 b3 b2 b1 b0
16
). Read out these bits after the occurrence of a data slicer interrupt (refer to 2.14.12
SS
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
pin, and make the length of wiring as short as possible so that a leakage
Test bits
Bit symbol
CRD3
CRD4
CRD5
CRD6
CRD7
Symbol
CRD
Clock run-in detection bits
Bit name
Address
0269
16
Number of reference clocks to
be counted in one clock run-in
pulse period.
Read-only
and ON-SCREEN DISPLAY CONTROLLER
Function
MITSUBISHI MICROCOMPUTERS
M306V5ME-XXXSP
When reset
00
16
M306V5EESP
R W
Rev. 1.0