ra8835 Topway Display, ra8835 Datasheet - Page 32

• Manufacturer Part Number: ra8835
• Description: Dot Matrix Lcd Controller
• Manufacturer: Topway Display

7. Functions Description
RAiO TECHNOLOGY INC.
Version 1.7
7-1 MCU Bus Interface
7-2 MCU Synchronization
7-1-1 8080 Series
7-1-2 6800 Series
7-2-1 Display Status Indication Output
7-2-2 Internal Register Access
SEL1, SEL2, A0, RD , WR and CS are used as control signals for the microprocessor data bus. A0 is
normally connected to the lowest bit of the system address bus. SEL1 and SEL2 change the operation
of the RD and WR pins to enable interfacing to either an 8080 or 6800 family bus, and should have a
pull-up or pull-down resistor. With microprocessors using an 8080 family interface, the RA8835 series
is normally mapped into the I/O address space.
The RA8835 series interface operates at full bus speed, completing the execution of each command
within the cycle time, t
polling or handshaking when accessing the RA8835 series.
Display flicker may occur if there is more than one consecutive access that cannot be ignored within a
frame. The microprocessor can minimize this either by performing these accesses intermittently, or by
continuously checking the status flag (D6) and waiting for it to become HIGH.
When CS , A0 and RD are LOW, D6 functions as the display status indication output. It is HIGH
during the TV-mode vertical retrace period or the LCD-mode horizontal retrace period, and LOW,
during the period the controller is writing to the display. By monitoring D6 and writing to the data
memory only during retrace periods, the display can be updated without causing screen flicker.
The SYSTEM SET and SLEEP IN commands can be used to perform input/output to the RA8835
series independently of the system clock frequency. These are the only commands that can be
A0
A0
0
1
0
1
0
1
0
1
CYC
Table-20A: 6800 Series Interface Signals
R/ W
Table-19: 8080 Series Interface Signals
RD
. The controlling microprocessor’s performance is thus not hampered by
0
0
1
1
1
1
0
0
WR
1
1
0
0
E
1
1
1
1
Status flag read
Display data and cursor address
read
Display data and parameter write
Command write
Status flag read
Display data and cursor address
read
Display data and parameter write
Command write
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Function
Function
Dot Matrix LCD Controller
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RA8835