S6A0079
34COM/120SEG DRIVER & CONTROLLER FOR DOT MATRIX LCD
FUNCTION DESCRIPTION
SYSTEM INTERFACE
This chip has all two kinds interface type with MPU: 4-bit bus and 8-bit bus. 4-bit bus and 8-bit bus is selected by
DL bit in the instruction register. During read or write operation, two 8-bit registers are used. one is data register
(DR), the other is instruction register(IR).
The data register(DR) is used as temporary data storage place for being written into or read from
DDRAM/CGRAM target RAM is selected by RAM address setting instruction. Each internal operation, reading
from or writing into RAM, is done automatically.
Hence, after MPU reads DR data, the data in the next DDRAM/CGRAM address is transferred into DR
automatically. Also after MPU writes data to DR, the data in DR is transferred into DDRAM/CGRAM
automatically.
The Instruction register(IR) is used only to store instruction code transferred from MPU. MPU cannot use it to
read instruction data.
To select register, use RS input pin in 4-bit/8-bit bus mode.
RS
0
0
1
1
R/W
0
1
0
1
Operation
Instruction write operation (MPU writes instruction code into IR)
Read busy flag (DB7) and address counter (DB0 - DB6)
Data write operation (MPU writes data into DR)
Data read operation (MPU reads data from DR)
BUSY FLAG (BF)
When BF = "High", it indicates that the internal operation is being processed. So during this time the next
instruction cannot be accepted. BF can be read, when RS = Low and R/W = High (Read Instruction Operation),
through DB7 port. Before executing the next instruction, be sure that BF is not high.
8
SAMSUNG [ SAMSUNG SEMICONDUCTOR ]
