W742E Datasheet, PDF (45/60 Pages) Winbond – 4 BIT MICROCONTROLLER

W742E/C811
Corresponding to the 40 LCD drive output pins, there are 160 LCD data RAM segments. Instructions
such as MOV LPL,R, MOV LPH,R, MOV @LP,R, and MOV R,@LP are used to control the LCD data
RAM. The data in the LCD data RAM are transferred to the segment output pins automatically without
program control. When the bit value of the LCD data RAM is "1," the LCD is turned on. When the bit
value of the LCD data RAM is "0," LCD is turned off. The contents of the LCD data RAM (LCDR) are
sent out through the segment0 to segment39 pins by a direct memory access. The relation between
the LCD data RAM and segment/common pins is shown below.
Table 6 The reation between the LCDR and segment/common pins used as LCD drive output
pins
OUTPUT
PIN
SEG0
SEG1
:
:
SEG38
SEG39
OUTPUT
PIN
SEG0
SEG1
:
:
SEG38
SEG39
LCD
RAM
LCDR01
LCDR03
:
:
LCDR4D
LCDR4F
LCD
RAM
LCDR81
LCDR83
:
:
LCDRCD
LCDRCF
COM7
BIT3
0/1
0/1
:
:
0/1
0/1
COM15
BIT3
0/1
0/1
:
:
0/1
0/1
COM6
BIT2
0/1
0/1
:
:
0/1
0/1
COM14
BIT2
0/1
0/1
:
:
0/1
0/1
COM5
BIT1
0/1
0/1
:
:
0/1
0/1
COM13
BIT1
0/1
0/1
:
:
0/1
0/1
COM4
BIT0
0/1
0/1
:
:
0/1
0/1
COM12
BIT0
0/1
0/1
:
:
0/1
0/1
LCD
RAM
LCDR00
LCDR02
:
:
LCDR4C
LCDR4E
LCD
RAM
LCDR80
LCDR82
:
:
LCDRCC
LCDRCE
COM3
BIT3
0/1
0/1
:
:
0/1
0/1
COM11
BIT3
0/1
0/1
:
:
0/1
0/1
COM2
BIT2
0/1
0/1
:
:
0/1
0/1
COM10
BIT2
0/1
0/1
:
:
0/1
0/1
COM1
BIT1
0/1
0/1
:
:
0/1
0/1
COM9
BIT1
0/1
0/1
:
:
0/1
0/1
COM0
BIT0
0/1
0/1
:
:
0/1
0/1
COM8
BIT0
0/1
0/1
:
:
0/1
0/1
The LCDON instruction turns the LCD display on (even in HOLD mode), and the LCDOFF
instruction turns the LCD display off. At the initial reset state, the LCD display is turned off
automatically. To turn on the LCD display, the instruction LCDON must be executed.
5.25.1 LCD RAM addressing method
There are 160 LCD RAMs (LCDR00H - LCDR4FH, LCDR80H - LCDR0CFH) that should be indirectly
addressed. The LCD RAM pointer (LP) is used to point to the address of the wanted LCD RAM but it
is not readable. The LP is organized as 8-bit binary register. The MOV LPL,R and MOV LPH,R
instructions can load the LCD RAM address from RAM to the LP register. The MOV @LP,R and MOV
R,@LP instructions can access the pointed LCD RAM content.
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Publication Release Date: December 2000
Revision A1