Obsługa wyświetlacza LCD z układem sterowania

HD44780U

flapo213 - elektroda ([e-mail])

1. Opis sygnałów sterujących



‘E’

– Enable przy przejściu z 1 na 0 umożliwia przepisanie za-

wartości z wejść danych do rejestrów.



‘RS’

– przełączanie rejestrów pomiędzy rejestrem danych a re-

jestrem instrukcji 0 – rejestr instrukcji, 1 – rejestr danych.



‘R/W’

– umożliwia zapianie danych do wyświetlacza bądź

sprawdzenia flag, 0 – zapis do wyświetlacza, 1 – odczyt flag z
wyświetlacza.



DB7...DB0

– wejścia danych / flagi. W trybie 8 bitowym wyko-

rzystwane są wejścia od DB7 do DB0, natomiast w trybie 4 bito-
wym wykorzystywana jest wyłącznie starsza połówka od DB7 do
DB4.



Vsc

– wejście napięcia kontrastu (napięcie zeleżne od napięcia

zasilania wyświetlacza).



Vcc

– napięcie zasilania zależnie od modelu 3,3V lub 5V.



Gnd

– masa napięcia zasilania.

2. Symbole używane przy konfiguracji procesora HD44780U



‘DL’

– szerokość magistrali danych, gdy DL = 0 szerokość 4

bitowa, DL = 1 szerokość 8 bitowa.



‘N’

– liczba wierszy, gdy N = 0 – jeden wiersz, 1 – dwa wier-

sze.



‘F’

– wybór wielkości fonta, gdy F = 0 – 5x8, F = 1 – 5x10.



‘D’

– załączenie / wyłączenie wyświetlacza, gdy D = 0 wy-

świetlacz wygaszony, D = 1 aktywny.



‘C’

– kursor widoczny / niewidoczny, gdy C = 0 niewidoczny,

C = 1 widoczny.



‘B’

– miganie kursora aktywne / nieaktywne, gdy B = 0 – brak

migania, B = 1 – miganie włączone.



‘I/D’

– inkrementacja / dekrementacja, gdy I/D = 1 inkremen-

tacja, I/D = 0 dekrementacja.



‘S’

– przesunięcie, S = 1 przesunięcie aktywne, S = 0 brak

przesunięcia.

3. Algorytm konfiguracji

Start -

Initialization

Start-up power

supply, add delay

5V option 15ms,

3,3V option 40ms

Set on pins RS =
0, R/W=0, DB7 =

0, DB6 = 0, DB5 =

1, DB4 = 1

Insert delay 4,1 ms

Set on pins RS =

0, R/W=0, DB7 =

0, DB6 = 0, DB5 =

1, DB4 = 1

Insert delay 100us

Set on pins RS =
0, R/W=0, DB7 =

0, DB6 = 0, DB5 =

1, DB4 = 1

Set on pins RS =
0, R/W=0, DB7 =

0, DB6 = 0, DB5 =

1, DB4 = 0

Switching to 4 bit

data length interface

Wait to power supply

reach 4,5V or 2,7V

Boot-up procedure of

HD44780 processor

If(DB7 == 1)

R/W = 1

Set on pins RS =
0, R/W=0, DB7 =

0, DB6 = 0, DB5 =

1

, DB4 =

DL

Wait until flage BF will be 1

indicate ready to get new

command

Set on pins RS =

0, R/W=0, DB7 =

N

, DB6 =

F

, DB5 =

1, DB4 = 0

This two block after if condition set up

4 bit interface length and

If DL = 0 set 4 bit interface length , DL = 1 set 8 bit

if N = 0 (1 row) or N = 1 (2 row),

F = 0 (5x8) or F = 1 (5x10)

If(DB7 == 1)

R/W = 1

Wait until flage BF will be 1

indicate ready to get new

command

Set on pins RS =
0, R/W=0, DB7 =

0, DB6 = 0, DB5 =

0, DB4 = 0

Set on pins RS =

0, R/W=0, DB7 =

1

, DB6 =

D

, DB5

=

C

, DB4 =

B

This two block after if condition set up

some display information

If D = 0 display info is turn off , D = 1 display is an active

if C = 0 cursor is turn off or C = 1 cursor is an active,

B = 0 static cursor or B = 1 blinking cursor

Yes

No

Yes

No

If(DB7 == 1)

R/W = 1

Set on pins RS =
0, R/W=0, DB7 =

0, DB6 = 0, DB5 =

0, DB4 = 0

Set on pins RS =
0, R/W=0, DB7 =

1

, DB6 =

D

, DB5

=

C

, DB4 =

B

Yes

No

Rest of initialization is in

on hd44780u_alg02

document

Pierwsza część algorytmu hdd44780u_alg01

Continous from

document

hd44780u_alg01

If(DB7 == 1)

R/W = 1

Set on pins RS =
0, R/W=0, DB7 =

0, DB6 = 0, DB5 =

0, DB4 =

1

Set on pins RS =
0, R/W=0, DB7 =

S/C

, DB6 =

R/L

,

DB5 = x, DB4 = x

Yes

No

Wait to last internal

operation is finished

Set options move cursor or shift display

S/C = 0 cursor move, S/C = 1 display shift

and R/L = 0 shift to left,

R/L = 1 shift to right, x - less worth state

If(DB7 == 1)

R/W = 1

Set on pins RS =
0, R/W=0, DB7 =

0, DB6 = 0, DB5 =

0, DB4 = 0

Set on pins RS =
0, R/W=0, DB7 =

0, DB6 =

1

, DB5 =

I/D

, DB4 =

S

Yes

No

Wait to last internal

operation is finished

Set options cursor move direction

and specifies display shift

I/D = 0 decrement, S/C = 1 increment

and S = 1 add display shift

If(DB7 == 1)

R/W = 1

Set on pins RS =
0, R/W=0, DB7 =

0, DB6 = 0, DB5 =

0, DB4 = 0

Set on pins RS =
0, R/W=0, DB7 =

0, DB6 = 0 , DB5 =

0, DB4 =

1

Yes

No

Wait to last internal

operation is finished

Clear all entire display and sets DDRAM

address to 0 in address counter

3 not described

options please

refer to HD44780u

manual

End of initialization

procedure of

HD44780u

Druga część algorytmu hdd44780u_alg01

4. Algorytm zmiany pozycji na wyświetlaczu.

Start Row Change

Set on pins RS =
0, R/W=0, DB7 =

1

, DB6 =

y

, DB5 =

x

, DB4 =

x

Set on pins RS =

0, R/W=0, DB7 =

x

, DB6 =

x

, DB5 =

x

, DB4 =

x

If(DB7 == 1)

R/W = 1

Yes

No

Exit Row Change

1 indicates operation change DDRAM actual

position, y - position if 0

choose row 1 and if 1 choose row 2, x - is

position on one row

Wait for internal

operation finish

Instruction to save 0x80

row 1 position 1

Instruction to save 0xC0

row 2 position 1

5. Algorytm zapisu znaku na wyświetlaczu.

Start Character

Save

Set on pins RS =
1, R/W=0, DB7 =

x

, DB6 =

x

, DB5 =

x

, DB4 =

x

Set on pins RS =

0, R/W=0, DB7 =

x

, DB6 =

x

, DB5 =

x

, DB4 =

x

If(DB7 == 1)

R/W = 1

Yes

No

End of Save

Character

A

Save Character for

instance ‘A’ is in ASCII

0x65

If You want to save a character to display You should

change RS to 1 and R/W to 0 and x is all position in

ASCII code table for instance character ‘A’ 0x65

6. Algorytm zapisu znaku specjalnego do pamięci znakowej CGRAM

Save New Character

in CGRAM

Set on pins RS =
0, R/W=0, DB7 =

0, DB6 =

1

, DB5 =

x

, DB4 =

x

Set on pins RS =

0, R/W=0, DB7 =

x

, DB6 =

x

, DB5 =

x

, DB4 =

x

If(DB7 == 1)

R/W = 1

Yes

No

End of Save New

Character in

CGRAM

Set on pins RS =
1, R/W=0, DB7 =

x

, DB6 =

x

, DB5 =

x

, DB4 =

x

Set on pins RS =
0, R/W=0, DB7 =

x

, DB6 =

x

, DB5 =

x

, DB4 =

x

If(DB7 == 1)

R/W = 1

Yes

No

If(i == 8)

i++

No

Yes

1 indicate that choose save instruction write to

CGRAM, all x is address to specyfic line, if you want

save 8 point hight character You should in x place

insert I variable (increment)

Wait to the the last internal operation is

finish

Save pattern of new one line character in

CGRAM

Wait to the the last internal operation is

finish

Save the 5x8 character save in CGRAM

0 0 0

0

1

0 0 0

0 0 0

0

1

0

1

0

0 0 0

0

1 1

0 0

0 0 0

0

1

0 0 0

0 0 0

1 1

0 0 0

0 0 0

0

1

0 0 0

0 0 0

0

1 1 1 1

0 0 0

0 0 0 0 0

Character 5x8 pixels

Character polish ‘ Ł’

0x08

0x0A

0xC0

0x80

0x18

0x08

0x0F

0x00

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