EM65568 ELAN Microelectronics Corp, EM65568 Datasheet - Page 24

• Manufacturer Part Number: EM65568
• Description: 130 Com/ 128 Seg 4096 Color Stn Lcd Driver
• Manufacturer: ELAN Microelectronics Corp

Read display RAM operation
The EM65568 can be read the control registers, in case of control register read operation, data bus upper nibble (D7-D4) use
for register address (0 to FH). In maximum, 16 registers can access directly. But number of register is more than 16 registers.
Therefore, EM65568 has register bank control. The RE register is set bank number to access. And the RE address is 0FH, in
any bank can access RE register. It is need 4-steps to read the specific register in maximum case.
7.4 16-bit Data Access to Display RAM
The EM65568 correspond to 8-bits and 16-bits bus size access.
The data bus size can select by WLS register.
In the 16-bits access mode, access for control register use low-byte data bus (D7~D0). Then high byte data bus (D15~D8) are
not used in internal circuit. When read control register using 16-bits bus. Register values output to D3-D0 and D15-D4 output
“H”.
* This specification is subject to be changed without notice.
Register read operation
WLS = “0”: 8-bits bus size
WLS = “1”: 16-bits bus size
(1) Write 04H to RE register for access to RA register.
(2) Writes specific register address to RA register.
(3) Write specific register bank to RE register.
(4) Read specific register contents.
(D0~D15)
D0~D7
W RB
RDB
RS
D0~D7
W RB
RDB
RS
Address set (AX,AY)
Address = n
n
Bank number write
Figure 7. Read display RAM operation
to RE for RA
Figure 8. Register read operation
04H
Dummy
***
Read
Address write
130 COM/ 128 SEG 4096 Color STN LCD Driver
addr
to RA
24
Data Read
Address=n
n
Bank number
write to RE
bank
Address=n+1
Data Read
n+1
read specific
register
data
Address=n+2
Data Read
n+2
2005/3/8 (V1.2)
EM65568