
x COMMAND 0 (System control setup 1)
First byte
Notes on command settings
1. RSTSYS: A command reset is executed immediately after the data is read.
The reset is cleared by returning the CS pin to high to reset this register. The reset is also cleared if this command is
executed consecutively or if this register is set to 0.
2. RAMCLR: The RAM can only be erased when display is off. This operation is not executed during display. This
operation cannot be executed if the LC oscillator is stopped. Only use this command when the LC oscillator is
operating.
This command bit is automatically cleared when the RAM erase operation completes.
Once the RAM erase command has been read in, the following time is required to complete the operation.
— Tclear = 5 [s] + 4/fOSC (LC-oscillator) × 288
3. OSCSTP: The LC oscillator stop command stops the LC oscillator connected to pins 2 and 3 (OSCIN and OSCOUT).
The oscillator stop command is only executed when display is off. It is not executed if display is in progress.
In external clock input mode, this command stops the acquisition of that clock signal.
4. TSTMOD: The test mode command is executed if the TESTIN pin (pin 5) is high. This command should not be used
by applications in normal operation.
Note: This register is set to 0 on a reset (either by the RST pin or by a command reset).
No. 5159-7/17
LC74772V
Register content
DA0 to DA7
Register name
State
Function
Note
7
—
0
6
—
0
Command 0 identification code
5
—
0
4
—
0
3
RST
0
Normal operation
If CS is low, the reset is executed, but if
SYS
1
System reset
CS is high this command will be excluded.
RAM
0
Normal operation
The VRAM clear operation is not
2
executed when the oscillator
CLR
1
Normal operation VRAM clear (All data is set to FE (hexadecimal)) is stopped.
OSC
0
The LC oscillator operating state is maintained.
Valid when the display is off. VRAM write
1
is not possible when the oscillator is
STP
1
The LC oscillator is stopped.
stopped.
0
TST
0
Normal operation
Illegal setting.
MOD
1
Test mode
This bit must always be set to 0.