ST7920

V4.0

17/49

2008/08/18

Instruction set 2: (RE=1: extended instruction)

Code

Inst.

RS

RW DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0

Description

Exec time

(540KHZ)

Standby

0

0

0

0

0

0

0

0

0

1

Enter standby mode, any other instruction can terminate.

COM1

…32 are halted.

72 us

Scroll or

RAM

Address.

Select

0

0

0

0

0

0

0

0

1

SR

SR=1: enable vertical scroll position

SR=0: enable CGRAM address (basic instruction)

72 us

Reverse

(by line)

0

0

0

0

0

0

0

1

R1

R0

Select 1 out of 4 line (in DDRAM) and decide whether to

reverse the display by toggling this instruction

R1,R0 initial value is 0,0

72 us

Extended

Function

Set

0

0

0

0

1

DL

X

1

RE

G

0

DL=1

:8-bit interface

DL=0

:4-bit interface

RE=1: extended instruction set

RE=0: basic instruction set

G=1

:graphic display ON

G=0

:graphic display OFF

72 us

Set Scroll

Address

0

0

0

1

AC5 AC4 AC3 AC2 AC1 AC0 SR=1: AC5~AC0 the address of vertical scroll

72 us

Set Graphic

Display

RAM

Address

0

0

1

0

0

0

AC5

0

AC4

AC3

AC3

AC2

AC2

AC1

AC1

AC0

AC0

Set GDRAM address to address counter (AC)

Set the vertical address first and followed the horizontal

address by consecutive writings

Vertical address range: AC5

…AC0

Horizontal address range: AC3

…AC0

72 us

Note:

1.

Make sure that ST7920 is not in busy state by reading the busy flag before sending instruction or data. If using delay loop instead, please

make sure the delay time is enough. Please refer to the instruction execution time.

2.

“RE” is the selection bit of basic and extended instruction set. After setting the RE bit, the value will be kept. So that the software doesn’t

have to set RE every time when using the same instruction set.