HD44780U Datasheet, PDF (26/59 Pages) Hitachi Semiconductor – Dot Matrix Liquid Crystal Display Controller/Driver

HD44780U
Instruction Description
Clear Display
Clear display writes space code 20H (character pattern for character code 20H must be a blank pattern) into
all DDRAM addresses. It then sets DDRAM address 0 into the address counter, and returns the display to
its original status if it was shifted. In other words, the display disappears and the cursor or blinking goes to
the left edge of the display (in the first line if 2 lines are displayed). It also sets I/D to 1 (increment mode)
in entry mode. S of entry mode does not change.
Return Home
Return home sets DDRAM address 0 into the address counter, and returns the display to its original status
if it was shifted. The DDRAM contents do not change.
The cursor or blinking go to the left edge of the display (in the first line if 2 lines are displayed).
Entry Mode Set
I/D: Increments (I/D = 1) or decrements (I/D = 0) the DDRAM address by 1 when a character code is
written into or read from DDRAM.
The cursor or blinking moves to the right when incremented by 1 and to the left when decremented by 1.
The same applies to writing and reading of CGRAM.
S: Shifts the entire display either to the right (I/D = 0) or to the left (I/D = 1) when S is 1. The display does
not shift if S is 0.
If S is 1, it will seem as if the cursor does not move but the display does. The display does not shift when
reading from DDRAM. Also, writing into or reading out from CGRAM does not shift the display.
Display On/Off Control
D: The display is on when D is 1 and off when D is 0. When off, the display data remains in DDRAM, but
can be displayed instantly by setting D to 1.
C: The cursor is displayed when C is 1 and not displayed when C is 0. Even if the cursor disappears, the
function of I/D or other specifications will not change during display data write. The cursor is displayed
using 5 dots in the 8th line for 5 × 8 dot character font selection and in the 11th line for the 5 × 10 dot
character font selection (Figure 13).
B: The character indicated by the cursor blinks when B is 1 (Figure 13). The blinking is displayed as
switching between all blank dots and displayed characters at a speed of 409.6-ms intervals when f_cp or f_OSC
is 250 kHz. The cursor and blinking can be set to display simultaneously. (The blinking frequency changes
according to f_OSC or the reciprocal of f_cp. For example, when f_cp is 270 kHz, 409.6 × 250/270 = 379.2 ms.)
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