interfacing lcd with mb90f387s

8/12/2019 Interfacing LCD With MB90F387S

1/40

Interfacing Displaytech 204ASeries LCD to MB90F387S


2/40

About the Displaytech 204A

Item Contents Unit

LCD type TN / STN / FSTN ---

LCD duty 1/16 ---

LCD bias 1/5 ---

Viewing direction 6 / 12 oclockModule size (W!H!T) 98 !60 !11.0 MAX (14.0 MAX W/LED BACKLIGHT) mm

Viewing area (W!H) 76 !25.2 mm

Number of characters (characters!lines) 20 !4 ---

Character matrix (W!H) 5 !8 dots

Character size (W!H) 2.95 !4.75 mm

Dot size (W!H) 0.55 !0.55 mm

Dot pitch (W!H) 0.60 !0.60 mm


3/40

External Dimensions


4/40

Actual Picture (Reverse Contrast Type)


5/40

Block Diagram


6/40

Interface Signals

Pin NO. Symbol Level Description

1 VSS 0V Ground

2 VDD 5.0V Supply voltage for logic

3 VO --- Input voltage for LCD

4 RS H/L H : Data signal, L : Instruction signal

5 R/W H/L H : Read mode, L : Write mode6 E H, H!L Enable signal for KS0076

7 DB0 H/L Data bit 0





12 DB5 H/L Data bit 513 DB6 H/L Data bit 6


15 A --- Back light anode

16 K --- Back light cathode


7/40

Registers

Instruction Register (IR)

stores instruction codes such as clear

display or shift cursor and also storesaddress information for the display dataRAM

Data Register

is used for temporarily storing data duringdata transactions with the MCU


8/40

Registers

Busy Flag (BF)

When the busy flag is set at a logical "1", the

LCD unit is executing an internal operation,and no instruction will be accepted

Address Counter (AC)

The address counter generates the address

for the display data RAM and charactergenerator RAM


9/40

Registers

Display Data RAM (DD RAM)

This 80 x 8 bit RAM stores up to 80 8-bit

character codes as display data

AC6 AC5 AC4 AC3 AC2 AC1 AC0

HEXDigit

AC

High-orderBits

Lower-orderBits

HEXDigit

1

Example: DD RAM address '4E'

0 0 1 1 1 0

4 E


10/40

Registers

Character Generator ROM (CG ROM)

This ROM generates a 5 !7 dot-matrix

character pattern for each of 160 different8-bit character codes

Character Generator RAM (CG RAM)

This RAM stores eight arbitrary 5 x 7 dot-

matrix character patterns, as programmedby the user


11/40

0000

HIGH-ORDER4 BIT

LOW-ORDER 4 BIT

0010 0011 0100 0101 0110 0111 1010 1011 1100 1101 1110 1111

xxxx0000

xxxx0001

xxxx0010

xxxx0011

xxxx0100

xxx0101

xxx0110

xxxx0111

xxxx1000

xxxx1001

xxxx1010

xxxx1011

xxxx1100

xxxx1101

xxxx1110

xxxx1111

CGRAM

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

Character Codes


12/40

MCU Interface

The LCD unit performs either dual 4-bit or single 8-

bit data transfers, allowing the user to interface with

either a 4-bit or 8-bit microprocessor

4-Bit Microprocessor Interface.

Data lines DB4 - DB7 are used for data transfers.

Data transactions with the external

microprocessor take place in two 4-bit data

transfer operations.


13/40

MCU Interface

8-bit Microprocessor Interface

Each 8-bit piece of data is transferred in a singleoperation using the entire data bus DB0 - DB7.


14/40


15/40

Initialization byInstruction 8-bit

Interface

Power ON

Wait 15 ms or moreafter VDDreaches 4.5 V

RS R/W DB7DB6DB5DB4DB3DB2DB1DB0

0 0 0 0 1 1 * * * *

Wait 4.1 ms or more


0 0 0 0 1 1 * * * *

Wait 100 s or more

End of Initialization


0 0 0 0 1 1 * * * *


0 0 0 0 1 1 N F * *

0 0 0 0 0 0 1 0 0 0

0 0 0 0 0 0 0 0 0 1

0 0 0 0 0 0 0 1 I/D S

Busy flag can't be checked before execution of thisinstruction

Function Set (8-Bit Interface)





(a) Busy flag can be checked after the following instructionsare completed. If the busy flag is not going to be checked,then a wait time longer than the total execution time ofthese instructions is required (See Table 7.)

Function Set

Display Off

Display Clear

Entry Mode Set

8-Bit Interface,Single/Dual LineDisplay, Display Font

Caution: At this point,the display formatan't be changed.

-


16/40

Power ON

Wait 15 ms or moreafter VDDreaches 4.5 V

RS R/W DB7DB6DB5DB4

0 0 0 0 1 1

Wait 4.1 ms or more

RS R/W DB7DB6DB5DB4

0 0 0 0 1 1

RS R/W DB7DB6DB5DB4

0 0 0 0 1 1

RS R/W DB7DB6DB5DB4

0 0 0 0 1 0

0 0 0 0 1 0

0 0 N F * *

Wait 100 s or more

End of Initialization







(a) Busy flag can be checked after the following instructionsare completed. If the busy flag is not going to be checked,then a wait time longer than the total execution time ofthese instructions is required (See Table 7.)

This instruction signals the LCD unit to begin accepting andsending data in dual 4-bit transfers for all subsequenttransfers for all subsequent transactions. This is the only4-bit instruction recognized by the LCD unit.

II Function Set

III Display Off

IV Display Clear

V Entry Mode Set

4-Bit Interface,Single/Dual LineDisplay, Display Font

0 0 0 0 0 0

0 0 1 0 0 0

0 0 0 0 0 O

0 0 0 0 0 1

0 0 0 0 0 0

0 0 0 1 I/D S

I Function Set (4-Bit Interface)I

II

III

IV

V

Caution: At this point,the display formatcan't be changed.

Initialization byInstruction 4-bit

Interface


17/40

Instruction Set

H


18/40

tAS

PWEH

tDSW

tcycE

tAH

tAH

VIHVIL

DB0 - DB7

tEf

tHtEr

VIHVIL

E

VILR/W

VIH

VILRS

VALID DATA

-

H

H

H

H

H

H

!

!

!

!

!

!

!

Write Operation Timing Characteristics


19/40

tAS

PWEH

tDDR

tcycE

tAH

tAH

VOHVOL

DB0 - DB7

tEf

tDHR

tEr

VIHVILE

VIHR/W

VIHVIL

RS

VALID DATA

I

I

I

I

I

-

!

!

!

!

!

!

!

Read Operation Timing Characteristics


20/40


21/40


22/40

LKS Expansion Board

LCD + Keypad + Stepper Motor


23/40

Video Demo


24/40


25/40

Programming

Step 1: Write a function to sendInstructions to LCD

Step 2: Write a function to Initialize LCD(initialize once)

Step 3: Write a function to send Data to

LCD Step 4: Write a function to display a string

to LCD


26/40

Demonstration #1

Flowchart for instCtrl() - function to sendinstruction to LCD (8-bit)


27/40

Flowchart for instCtrl()function


28/40

Sample Code (C)

void instCtrl(unsigned char inst)

{

IO_PDR2.byte = inst; // load 8-bit instruction to 8-bit LCD data lines

IO_PDR5.bit.P50 = 0; // set RS to 0 (instruction register)

IO_PDR5.bit.P51 = 0; // set RW to 0 (write mode)

IO_PDR5.bit.P52 = 1; // set E to 1 (initial state)

delay(1); // base delay is 16 us

IO_PDR5.bit.P52 = 0; // set E to 0 (H-L: final state)

readBF(); // read busy flag;

}


29/40

Reading the Busy Flag


30/40

Sample Code (C)void readBF()

{

unsigned char flag;

IO_DDR2.byte = 0x00; // set direction of LCD data lines to input


IO_PDR5.bit.P51 = 1; // set RW to 1 (read mode)


do {

flag = IO_PDR2.bit.P27; // read bit 7 of Port 2 (busy flag)

} while (flag);


IO_DDR2.byte = 0xFF; // set direction of LCD data lines back to output

}


31/40

Seatwork #1

Flowchart and code for dataCtrl() -function to send instruction to LCD (8-bit)

Flowchart and code for initLCD() -function to send initialize the LCD (2-line,Cursor on, blink off)


32/40

Demonstration #2

Flowchart for instCtrl() - function to sendinstruction to LCD (4-bit)


33/40

Flowchart fordataCtrl()

function 4-bit interface(8-bit transfer)


34/40

Sample Code (C)void instCtrl(unsigned char inst)

{

IO_DDR2.byte = inst>> 4; // transfer the upper4-bit of inst to 4-bit LCD data line


IO_PDR5.bit.P52 = 0; // set RW to 0 (write mode)


delay(1); // delay for 16 us


IO_DDR2.byte = inst; // transfer the lower 4-bit of inst to 4-bit LCD data line


delay(1); // delay for 16 us


readBF(); // read busy flag

}


35/40

Flowchart for instCtrl()function 4-bit interface

(4-bit transfer for LCD initializationpurposes)


36/40

Seatwork #2

Flowchart and code for dataCtrl() -function to send data to LCD (4-bit)


37/40

Demonstration #3

Displaying text to the LCD

displaying Hello! at the center of the 2nd line


38/40

Character Display Addresses

Line 1 (0x80 - 0x93)

Line 3 (0x94 - 0xA7)

Line 2 (0xC0 - 0xD3)

Line 4 (0xD4 - 0xE7)

Hello!

Line 1 address continue to Line 3 while Line 2 continues at Line 4.


39/40

Sample Code (C).

.

instCtrl(0xC6); // move cursor to 2nd line 7th column

dataCtrl(H); // prints H at current cursor position

// then shifts the cursor to the right*

dataCtrl(E); // prints E

dataCtrl(L); // prints L

dataCtrl(L); // prints L

dataCtrl(O); // prints O

dataCtrl(!); // prints !.

.

* assuming configuration is cursor shift to right


40/40

Sources

Sharp HD44870 LCD Datasheet

Displaytech 204A Datasheet

interfacing lcd with mb90f387s

Documents