S6A0074 Datasheet, PDF (9/68 Pages) Samsung semiconductor – 34COM/80SEG DRIVER & CONTROLLER FOR DOT MATRIX LCD

34COM/80SEG DRIVER & CONTROLLER FOR DOT MATRIX LCD
S6A0074
FUNCTION DESCRIPTION
SYSTEM INTERFACE
This chip has all three kinds interface type with MPU: serial, 4-bit bus and 8-bit bus. Serial and bus (4-bit/8-bit) is
selected by IM input, and 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/SEGRAM,
target RAM is selected by RAM address setting instruction. Each internal operation, reading from or writing into
RAM, is done automatically.
So to speak, after MPU reads DR data, the data in the next DDRAM/CGRAM/SEGRAM address is transferred
into DR automatically. Also after MPU writes data to DR, the data in DR is transferred into
DDRAM/CGRAM/SEGRAM 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/CS input pin in 4-bit/8-bit bus mode (IM = "High") or RS bit in
serial mode (IM = "Low").
RS
R/W
Operation
0
0
Instruction write operation (MPU writes Instruction code into IR)
0
1
Read busy flag (DB7) and address counter (DB0 - DB6)
1
0
Data write operation (MPU writes data into DR)
1
1
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 Before executing the next instruction, be sure that BF is not High.
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