NT6862 Datasheet, PDF (24/57 Pages) List of Unclassifed Manufacturers – 8-Bit Microcontroller for Monitor

NT6862-5xxxx
12.5. PORT4: P40 - P41
PORT4 is available only on the 42pin SDIP IC. PORT40 - PORT41 is an 2-bit bi-directional CMOS I/O port with PMOS as
internal pull-up (Figure 12.1). Each bi-directional I/O pin may be bit programmed as an input or output port without software
control the data direction register. When PORT4 works as output, the data to be output is latched to the port data register
and output to the pin. PORT4 pins that have '1's written to them are pulled HIGH by the internal PMOS pull-ups. In this state
they can be used as input. The input signal can be read. This port outputs HIGH after reset.
Addr. Register INIT
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0 R/W
$0005
PT4
FFH
-
-
-
-
-
-
P41
P40
RW
13. H/V Sync Signals Processor
The functions of the sync processor include polarity detection, Hsync & Vsync signals counting, and programmable sync
signals output. It also provides 3-sets of free running signals and special output of test pattern at burn-in process when
activating the free running output function. The NT6862 can properly handle either composite or separate sync signal inputs
even without sync signal input. As to processing the composite sync signal, a hardware separator will be activated to extract
the HSYNC signal under user controlled. The input at HSYNCI can be either a pure horizontal sync signal or a composite
sync signal. For the sync waveform refer to Figure 13.1 & Figure 13.2.
The sync processor block diagram is shown in Figure 13.3. The HSYNCI pin contains a jitter filter. For the Hsync signal from
VGA card with heavy jitter, the filter could effectually reduce the jitter interference. Both VSYNCI & HSYNCI pins have
Schmitt Trigger and filtering process to improve noise immunity. Any pulse that is shorter than 125 ns, will be regarded as a
glitch and will be ignored.
(a) Positive polarity
(b) Negative polarity
Figure 13.1. Separate H Sync. Waveform
(a) Positive Polarity
(b) Negative Polarity
Figure 13.2. Composite H Sync. Waveform
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