LCDGR Operations


LCDGR Unit

Graphical LCDs come with a great variety of colors, resolutions and sizes. This project makes use of a simple 128 x 64 dots matrix LCD (Varitronix MGLS12864). The pin configurations of the module are shown in Table I. Programming through its display driver 61103A is easy. Simply define the starting coordinates on the screen before writing the display graphics in ASCII codes. The instruction sets of the driver are given in Table II.


TABLE I : LCD 12864 Specifications
SYMBOL PIN # FUNCTION
/CSA 1 logic=1 for right half of screen
/CSB 2 logic=1 for left half of screen
Vss 3 Ground
Vd 4 +5V Power Supply
Vo 5 Negative voltage supply for LCD driver
D/I 6 Register Select: 1 for data; 0 for instruction code
RW 7 Read/Write: 1 to read; 0 to write into module
E 8 State data read/write
DB0 to DB7 7 - 16 bi-directional data bus terminals


LCD Instructions

When both RS and RW are OFF, DB0-DB7 represent instructions. On the other hand, DB0-DB7 hold data in ASCII codes to be read/written when RS and RW are not all zero. In a status read, the LCD sends out a high logic at DB7 when it is busy.



Instruction E DI RW D7 D6 D5 D4 D3 D2 D1 D0
Display ON/OFF ^ 0 0 0 0 1 1 1 1 1 1
0
Display Start Line ^ 0 0 1 1 A D D R E SS
(0- 63)
Set Display Line Addr ^ 0 0 1 0 1 1 1 ADD RE SS
( 0 - 7 )
Set Horiz. Addr ^ 0 0 0 1 A D D R E SS
Auto Increment (0- 63)
Status Read ^ 0 1 B 0 O/F R/N 0 0 0 0
Busy for B=1
Write data to Display RAM ^ 1 0 D D D D D A T A
Read data to Display RAM ^ 1 1 D D D D D A T A
TABLE II (X=1 or 0)
1