RA8816
Preliminary Version 1.6
144x65 Character/Graphic LCD Driver
CS
SDI
RW
RS(1)
WD7 WD6 ……………. WD0
Don’t Care
RD7 RD6 ……………... RD0
Mem. R/W Data
SDO
SCK
Figure 6-22: Memory Read/Write Access on 4-Wires(B-Type) I/F
6-2 Memory
The RA8816 built-in three memory:
1. 256Kbyte Font ROM
2. 1170Byte Display RAM
3. Character Generator RAM(CGRAM)
The 256Kbyrte Font ROM stores bit map data of Chinese font. It also including English, Japaness,
Europen, Latin(Latin-ext A, Latin-ext B) and ASCII. In text mode, RA8816 will read the bit map data
from Font ROM and pass to display RAM that when RA8816 received the standard code from MPU.
The LCD control citcuit will read data of display RAM continuous and send to driver circuit. So the text
will show on the LCD screen. Therefore, the MPU will save a lot of time to caculate the position of
cursor and read mant bit map data from font ROM then write to dispaly RAM. The MPU will promote
the display efficiency to handle Chinese text display. And it will reduce the system develope time.
The display range of RA8816 is 144x65 dots. So it needs 1170Byte(144*65/8) display RAM. In
addition, RA8816 also built-in a scroll buffer to provide the scrlling and shiftting functions.
The Character Generator RAM(CGRAM) is used for user to create special fonts. There are eight space
of full size font to reserved for user. Their codes are fixed from FFF0h to FFF7h. The MPU could write
the mapping code to RA8816 and show the bit map font on screen that after the user font(writing 32
byte to CGRAM) was created.
6-3 System Clock
The clock of RA8816 is generated by the internal circuit. Normally the clock frequency is around
55KHz. When the bit0(SLP) of register PWRR set to “1”, then the clock will be stop.
Whe the input pin “CLK_SEL” set to “0”, then system clock can also input from external clock through
pin “EXT_CLK”.
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