Motorola MC68HC05T16 Technical Data Manual page 85

ON/OFF - OSD display on/off
1 (set) – OSD display on.
0 (clear) – OSD display off.
For the fading feature, the whole screen is divided into several 16-horizontal-line segments. Notice
that a row might not fit into the 16-horizontal-line segments. It might cross two segments,
depending on the vertical position of a row. The way that fade-in feature works is that one line in
all 16-line segments will appear in the first fading sequence; two lines, including the one line in the
first fading sequence, will appear in the second fading sequence; four lines, including the two lines
in the second fading sequence, will appear in the third fading sequence; eight lines, including the
four lines in the third fading sequence, will appear in the fourth fading sequence; and finally, all
sixteen lines, including the eight lines in the fourth fading sequence, will appear in the fifth fading
sequence. Fade-out feature works in the opposite manner, that is, the number of display lines to
be disappeared are 8 lines, 12 lines, 14 lines, 15 lines, and all 16 lines in each disappearance
sequence, respectively. Fade out sequence for a character in a row fitting right into the
16-horizontal-line segment is illustrated in Figure 9-7. Fading rate is fixed at 32 frames per
sequence. Therefore, it takes 160 frames to execute the fade function. At 60 Hz vertical frequency,
this will take five plus seconds. Note that when display disappears, all output pins are not
tri-stated, rather they remain in their deserted states.
CDRC3 to CDRC0 - Terminated display rows
These status bits reflect the number of row displays that have been terminated. These bits are
reset only by vertical flyback and incremented by one every time a row display has been
terminated.
9.5.2 Frame Control Register 2
Address bit 7
$1E BR1
BR1, BR0 - Blink rate select
These bits control the blinking rate of all symbols on the TV screen. The on/off ratio of blinking is
always 3/1.
VFPOL - VFLBK input polarity select
1 (set) – Vertical flyback signal at VFLBK is active low.
0 (clear) – Vertical flyback signal at VFLBK is active high.
MC68HC05T16
bit 6 bit 5 bit 4
BR0 VFPOL HFPOL HTPOL
ON-SCREEN DISPLAY
bit 3 bit 2 bit 1
FBPOL RGBPOL IPOL
State
bit 0
on reset
0000 0000
TPG
MOTOROLA
9-15
9