3 lcd display operation, Toshiba – Toshiba TMP87CP24AF User Manual
Page 97
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TOSHIBA
TMP87CM24A/P24A
2.10.3 LCD Display Operation
(1) Display data setting
Display data is stored to the display data area (assigned to address 0F80 to 0F93
h
) in the DBR. The
display
data
which
are
stored
in
the
display
data
area
is
automatically
read
out
and
sent
to
the
LCD
driver
by
the
hardware.
The
LCD
driver
generates
the
segment
signal
and
common
signal
according
to
the
display
data
and
driving
method.
Therefore,
display
patterns
can
be
changed
by
only
over
writing
the
contents
of
display
data
area
by
the
program.
Figure
2-48
shows
the
correspondence
between the display data area and SEG/COM pins.
LCD
light
when
display
data
is
"1"
and
turn
off
when
"0".
According
to
the
driving
method
of
LCD,
the
number
of
pixels
which
can
be
driven
becomes
different,
and
the
number
of
bits
in
the
display
data area which is used to store display data also becomes different.
Therefore,
the
bits
which
are
not
used
to
store
display
data
as
well
as
the
data
buffer
which
corresponds
to
the
addresses
not
connected
to
LCD
can
be
used
to
store
general
user
process
data
(see Table 2-12.)
Address
Bit 7 Bits Bits Bit 4
Bits Bit 2 Biti Bito
0F80
h
1 1 1
SEG1
1 1 1
SEGO
81
SEG3
SEG2
82
SEG5
SEG4
83
SEG7
SEG6
84
SEG9
SEG8
85
SEG11
SEG10
86
SEG13
SEG12
87
SEG15
SEG14
88
SEG17
SEG16
89
SEG19
SEG18
8A
SEG21
SEG20
88
SEG23
SEG22
8C
SEG25
SEG24
8D
SEG27
SEG26
8E
SEG29
SEG28
8F
SEG31
SEG30
90
SEG33
SEG32
91
SEG35
SEG34
92
SEG37
SEG36
93
, SEG39 ,
, SEG38 ,
COM3 COM2 COMI COMO
COM3 COM2 COMI COMO
Table 2-12. Driving Method and Bit for Display Data
Driving methods
Bit 7/3
Bit 6/2
Bit 5/1
Bit 4/0
1/4 Duty
COM3
COM2
COMI
COMO
1/3 Duty
-
COM2
COMI
COMO
1/2 Duty
-
-
COMI
COMO
Static
-
-
-
COMO
Note:
This bit is not used for display data
Figure 2-48. LCD Display Data Area (DBR)
(2) Blanking
Blanking is enabled when EDSP is cleared to "0".
Blanking
turns
off
LCD
through
outputting
a
non-selective
level
to
COM
pin.
A
signal
level
is
continuously
output
to
SEG
pin
according
to
display
data
and
driving
method.
For
static
drive,
lights-
out by data (clearing display data to "0") does not apply any voltage between pins COM and SEG. On
the
other
hand,
lights-out
by
blanking
makes
the
output
to
COM
pin
at
a
non-selective
level,
so
that
the part between pins COM and SEG becomes in the state driven by non-selective level.
3
-
24-97
2002
-
10-03