Datasheet
DEM 16217 SYH-LY    Product Specification         
Version : 5.1.4    PAGE: 9
11. CONTROL AND DISPLAY COMMAND 
Command  RS  R/W  DB7  DB6 DB5  DB4  DB3 DB2 DB1 DB0
Execution time
(fosc=270KHz)
Remark 
Clear 
Display 
0  0  0 0 0 0  0  0  0  1  1.52ms 
Write”20H” to DDRAM. And set 
DDRAM address to “00H” from AC 
Return home 0  0  0 0 0 0  0  0  1  x  1.52ms 
Set DDRAM address to “00H” from AC 
and return cursor to its original position if 
shifted. The contents of DDRAM are not 
changed. 
Entry mode 
Set 
0  0  0 0 0 0  0  1  I/D S  37us 
Sets cursor move direction and specifies 
display shift. These operations are 
performed during data write and read. 
Display 
on/off 
control 
0  0  0 0 0 0  1  D  C  B  37us 
D=1: entire display on 
C=1: cursor on 
B=1: cursor position on 
Cursor 
or 
Display Shift 
0  0  0 0 0 1 S/C R/L x  x  37us 
Set cursor moving and display shift 
control bit, and the direction, without 
changing DDRAM data. 
function 
Set 
0 0 0 0 1 DL N F  x  x  37us 
DL: interface data is 8/4 bits 
N: number of line is 2/1 
F: font size is 5x11/5x8 
Set CGRAM 
address 
0  0  0  1  AC5  AC4  AC3 AC2 AC1 AC0 37us  Set CGRAM address in address counter 
Set DDRAM 
address 
0  0  1  AC6 AC5  AC4  AC3 AC2 AC1 AC0 37us  Set DDRAM address in address counter 
Read busy 
flag& 
address 
0 1 BF AC6 AC5 AC4 AC3 AC2 AC1 AC0 0us 
Whether during internal operation or not 
can be known by reading BF. The contents 
of address counter can also be read. 
Write data 
to RAM 
1  0  D7 D6 D5 D4  D3  D2  D1  D0  37us 
Write data into internal RAM 
(DDRAM/CGRAM) 
Read data 
from RAM 
1  1  D7 D6 D5 D4  D3  D2  D1  D0  37us 
Read data from internal RAM (DDRAM / 
CGRAM) 
Note: 
Be sure the ST7066U is not in the busy state (BF=00 before sending an instruction from the MPU to the ST7066U. If 
an instruction is sent without checking the busy flag, the time between the first instruction and next instruction will 
take much longer than the instruction time itself. Refer to instruction table for the list of each instruction execution 
time. 










