Rainbow Electronics HD44780 - Manual (Page 32)

HD44780U
32
Interfacing the HD44780U
Interface to MPUs
•
Interfacing to an 8-bit MPU
See Figure 16 for an example of using a I/O port (for a single-chip microcomputer) as an interface
device.
In this example, P30 to P37 are connected to the data bus DB0 to DB7, and P75 to P77 are connected to
E, R/
W, and RS, respectively.

*
 
0
    & ,


+ ,
RS
R/W
E
Internal
operation
DB7
Functioning
Data Busy Busy
Not
busy
Data
Instruction
write Busy flag
check Busy flag
check Busy flag
check Instruction
write
Figure 15 Example of Busy Flag Check Timing Sequence
P30 to P37
P77
P76
P75
16
40
H8/325 HD44780U
8
DB0 to DB7
E
RS
R/W
LCD
COM1 to
COM16
SEG1 to
SEG40
Figure 16 H8/325 Interface (Single-Chip Mode)