參數(shù)資料
型號： 68HC05BD7
廠商： Motorola, Inc.
英文描述： 8-Bit Microcontroller Units (MCU).(8位微控制器)
中文描述： 8位微控制器單元（MCU）。（8位微控制器）
文件頁數(shù)： 59/85頁
文件大?。?/td> 302K
代理商： 68HC05BD7
SECTION 10: SYNC PROCESSOR
MOTOROLA
Page 49
MC68HC05BD7 Rev. 2.0
GENERAL RELEASE SPECIFICATION
PRELMNARY
vertical frequency register encompasses vertical frequency range from about 15 Hz to 127
Hz. Due to the asynchronous timing between incoming
VSYNC
and internal processor
clock, there will be
±
1 count error on the reading from the register for the same vertical
frequency. The horizontal counter counts the pulses on
HSYNC
pin, and is uploaded to the
$0F and $10 registers every 32.768ms. The step unit in the lower 5-bit register is
0.3125KHz. And the least 7 bits in the HFHR register shows the number of KHz of incoming
HSYNC
signal. The MSB of the HFHR is the overflow flag of H-counter, which will be
cleared when the register is read by CPU.
SECTION 10
SYNC PROCESSOR
10.1
Introduction
The functions of the module include polarity detection, horizontal frequency counter,
vertical frequency counter, and polarity controllable
HSYNO
and
VSYNO
outputs of various
input sources, such as separate H & V, Composite Sync from
HSYNC
, Sync-On-Green, or
internal free running H & V pulses. Besides, it also provides the
CLAMP
pulse output to the
external Pre-Amp chip. The
SOGIN
bit in
SPIOCR
register will determine the Composite
Sync input pin. All
HSYNC
,
VSYNC
, and
SOG
inputs have internal schmitt trigger to
improve noise immunity.
10.2
Functional Blocks
10.2.1
Polarity Detection
The
HSYNC
polarity detection circuit will measure the length of high period of
HSYNC
inputs. If the length of high is longer than 7us and the length of low is shorter than 6us, the
HPOL
bit will be zero, indicates negative polarity. If the length of low is longer than 7us and
the length of high is shorter than 6us, the
HPOL
bit is one, positive polarity. The
VSYNC
polarity detection circuit perform the similar structure with
HSYNC
polarity detection circuit.
If the length of high is longer than 4ms and the length of low is shorter than 2ms, the
VPOL
bit will be zero, indicates negative polarity. If the length of low is longer than 4ms and the
length of high is shorter than 2ms, the
VPOL
bit is one, positive polarity. Both
HSYNC
and
VSYNC
polarity flags are read-only, and will not affect any internal circuitry. When the
COMP
bit in
SPCSR
register is set, the
HPOL
bit will be the same as
VPOL
bit which is
detected under the criteria stated in previous statements.
10.2.2
Sync Signal Counters
There are two counters (horizontal frequency counter and vertical frequency counter) to
count the number of horizontal sync pulses within 32ms period and the number of system
clock cycles between two vertical sync pulses. These two data can be read by the CPU to
check the signal frequencies and can be used to determine the video mode. The 13-bit
10.2.3
Polarity Controlled HSYNO/VSYNO Outputs
The input
HSYNC
and
VSYNC
signal can be output to PC6 and PC7 when the
configuration bit of PC6 and PC7 in register $0B are set for SYNC output. Two
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