LCD UNIT USAGE INSTRUCTIONS
Interface with External Microprocessor
1. 8-bit Microprocessor
a. Interface to 8-Bit Microprocessor via Peripheral
Interface Adaptor (PIA). The following exempli-
fies the connection of the LCD unit to an 8-bit
microprocessor chip through a PIA or I/0 port.
The interface is TTL compatible. PB
0
- PB
7
of
the interface device are connected to DB
0
- DB
7
of the LCD unit, and PA
0
- PA
2
are connected to
E, R/W, and RS respectively.
When the PIA is used, care must be taken to
insure the proper relationship between the E
signal and other signals when reading and writ-
ing data.
RS
R/W
E
OPERATING
STATUS
DB
7
INTERNAL OPERATION
Write Instruction
Write Instruction
Check Busy Flag
Check Busy Flag
Check Busy Flag
READY FOR DATA
DATA
BUSY
BUSY
NOT
BUSY
DATA
LCD27-27
Figure 8. 8-Bit Interface Timing (Example)
A
15
A
14
A
13
A
1
A
0
R/W
VMA
φ
2
DB
0
-
DB
7
MC6800
8
MC6821
CS
2
CS
1
CS
0
RS
1
RS
0
R/W
E
D
0
-
D
7
PA
2
PA
1
PA
0
PB
0
-
PB
7
8
LCD UNIT
RS
R/W
E
DB
0
- DB
7
LCD27-28
Dot-Matrix LCD Units
Display Unit User’s Manual
21
