Rainbow Electronics HT49R70A-1 - Manual (Page 20)

HT49R70A-1
Rev. 1.00 20 December 4, 2001
LCD display memory
The HT49R70A-1 provides an area of embedded data
memory for LCD display. This area is located from 40H
to 68H of the RAM at Bank 1. Bank pointer (BP; located
at 04H of the RAM) is the switch between the RAM and
the LCD display memory. When the BP is set as ²1², any
data written into 40H~68H will affect the LCD display.
When the BP is cleared to ²0², any data written into
40H~68H is meant to access the general purpose data
memory. The LCD display memory can be read and
written to only by indirect addressing mode using MP1.
When data is written into the display data area, it is auto-
matically read by the LCD driver which then generates
the corresponding LCD driving signals. To turn the dis-
play on or off, a ²1² or a ²0² is written to the correspond-
ing bit of the display memory, respectively. The figure
illustrates the mapping between the display memory
and LCD pattern for the HT49R70A-1.
Q
D
C K
S
Q D a t a B u s
W r i t e
C h i p R e s e t
R e a d I / O
S y s t e m
W a k e - u p
( P A o n l y )
W e a k
P u l l - u p
P A 0 ~ P A 7
P C 0 ~ P C 7
O p t i o n
V
D D
O p t i o n
( P A 0 ~ P A 3 ,
P C )
V
D D
O p t i o n
( P A 0 ~ P A 3 , P C )
D a t a b u s
R e a d I / O
W e a k
P u l l - u p
P B 0 ~ P B 7
V D D
C / N M O S
Input/output ports Input ports
4 0 H
C O M
0
1
2
3
S E G M E N T
4 1 H 4 2 H 4 3 H 6 6 6 7 6 8 B i t
0
1
2
3
0 1 2 3 3 8 3 9 4 0
Display memory