RA8816
Preliminary Version 1.6
6-1-3 Register Read/Write
144x65 Character/Graphic LCD Driver
The RA8816 accepts two access cycles from MPU. One is read data from register or write data to
register. Another is read data from memory or write data to memory. As description of Chapter 5-2,
MPU must tell the RA8816 that which register will be access. Therefore the first data that write to
RA8816 is to select the register number. And the second data is the exact data that writing into or
reading from this register.
Because the features of RA8816 are controlled by the contents of internal registers. So if we write
data to register is like to give a command to RA8816. Therefore we can say that the Register
Access Cycle is same as Command Cycle.
The Figure 6-7 and 6-8 show the register access timing of 8080 MPU(8-Bit) with RA8816. Figure 6-9
and 6-10 show the register access timing of 6800MPU(8-Bit) interface. Figure 6-11 to 6-14 show the
register access timing of serial interface.
DB[7:0]
CS
DB[7:0]
CS
REG No.
DATA
REG No.
DATA
WR
WR
RD
RD
D/C
D/C
Figure 6-7: Register Wrie on 8080(8-Bit) I/F
Figure 6-8: Register Read on 8080(8-Bit) I/F
DB[7:0]
CS
DB[7:0]
CS
REG No.
DATA
REG No.
DATA
R/W
EN
R/W
EN
RS
RS
Figure 6-9: Register Write on 6800(8-Bit) I/F
Figure 6-10: Register Read on 6800(8-Bit) I/F
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