EM73PA88A
4-BIT MICRO-CONTROLLER FOR LCD PRODUCT
EI
: Enable interrupt Flip-Flop may promit or inhibit all interrupt sources, when inter-
rupt occurs, EI is auto cleared to "0", after RTI instruction is executed, EI is auto
set to "1" again.
Priority checker : Check interrupt priority when multiple interrupts occur.
INTERRUPT OPERATION
The procedure of interrupt operation :
1. Push PC and all flags to stack.
2. Set interrupt entry address into PC.
3. Set SF= 1.
4. Clear EI to inhibit other interrupts occur.
5. Clear the IL with which interrupt source has already been accepted.
6. Excute interrupt subroutine from the interrupt entry address.
7. CPU accept RTI, restore PC and flags from stack. Set EI to accept other interrupt requests.
PROGRAM EXAMPLE: To enable interrupt of "INT0, TRGA"
LDIA #0100B;
EXAE; set mask register "1100b"
EICIL 010111B ; enable interrupt F.F. and clear IL3 and IL5
LCD DRIVER
It can directly drive the liquid crystal display ( LCD ) and has 64 segments, 16 commons output pins.
There are total 64x16 dots can be display. The V1~V5 are the LCD bias voltage input pins.
(1) LCD driver control command register:
Port27 3
LDC
2
1
*
0
*
Initial value: 0000
LCD DISPLAY CONTROL
LDC
0 0
0 1
1 0
1 1
Function description
LCD display disable
Blanking
no function
LCD display enable
* : Don't care.
P27 is the LDC driver control command register. The initial value is 0000.
When LDC ( bit2 and bit3 of P27 ) is set to "00", the LCD display is disabled.
When LDC is set to "01", the LCD is blanking, the COM pins are inactive and the SEG pins
output the display data continuously.
When LDC is set to "11", the LCD display is enabled.
(2) LCD display data area:
The LCD display data is stored in the display data area of the data memory (RAM). The LCD display data
area is as illustrated below :
* This specification are subject to be changed without notice.
10.8.2001
23
ELAN [ ELAN MICROELECTRONICS CORP ]
